HUMAN NUTRITION

1 LITHUANIAN UNIVERSITY OF HEALTH SCIENCES

VETERINARY ACADEMY

DEPARTMENT OF ENVIRONMENTAL AND OCCUPATIONAL MEDICINE

Projektas „Slaugos, Veterinarinės maisto saugos ir Visuomenės sveikatos studijų

programų atnaujinimas, skatinant tarptautiškumą (SVeViT)“

Projekto kodas VP1-2.2-ŠMM-07-K-02-050

HUMAN NUTRITION

Rūta Ustinavičienė, Dalia Lukšienė

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Leidinys aprobuotas Lietuvos sveikatos mokslų universiteto Veterinarijos akademijos

Veterinarijos fakulteto tarybos posėdyje 2012-11-15 (protokolo Nr. 10). ir Lietuvos

sveikatos mokslų universiteto Leidybos komisijoje 2013 m. kovo 15 d. protokolo

Nr.3/13

Recenzavo:

Prof. Abdonas Tamošiūnas

Doc. Vidmantas Januškevičius

© Rūta Ustinavičienė, 2012 © Dalia Lukšienė, 2012

ISBN 978-9955-15-258-3

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CONTENT

1. Healthy nutrition: food and nutrition guidelines 3 2. Body mass evaluation methods. Human energy requirements. 7 3. Proteins. Classification of amino acids. Sources of protein in diet. 15 4. Fats and fatty acids, their classification. Sources of fats and cholesterol

in diet.

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5. Carbohydrates and their classification. Insoluble and soluble fibre, their impact on health. Sources of carbohydrates in diet.

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6. Vitamins 27

7. Minerals and trace elements 37

8. Nonbacterial food poisoning 48

9. Bacterial food poisoning 53

10. Food allergens, their classification and health effects 56

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1. Healthy nutrition: food and nutrition guidelines

Nutrition is the sum of total of the process involved in taking in nutrients and assimilating them into the body so that the body functions properly and health is maintained. Nutrition means more than just the adequate provision of essential major and minor nutrients; there is more to eating than mere nourishment. It is an important source of pleasure as well as social interaction and so has cultural significance. Nutrition is a critical part of health and development. Healthy nutrition requires appropriate dietary intake of energy in the form of macronutrients as well as the adequate intake of essential nutrients, comprising vitamins, trace elements, minerals, essential fatty acids and essential amino acids. Thus, healthy nutrition is related to improved infant, child and maternal health, stronger immune systems, safer pregnancy and childbirth, lower risk of non-communicable diseases (such as diabetes and cardiovascular disease), and longevity. People with adequate nutrition are more productive and can create opportunities to gradually break the cycles of poverty and hunger. Malnutrition has traditionally been regarded as the outcome of a lack of sufficient energy or specific nutrients (undernutrition). Malnutrition, in every form, presents significant threats to human health. Today the world faces a double burden of malnutrition that includes both undernutrition and obesity, especially in developing countries. Obesity is one of the greatest public health challenges of the 21st century. Its prevalence has tripled in many countries of the WHO European Region since the 1980s, and the numbers of those affected continue to rise at an alarming rate, particularly among children. In addition to causing various physical disabilities and psychological problems, excess weight drastically increases a person’s risk of developing a number of noncommunicable diseases such as cardiovascular disease, cancer and diabetes.

World Health Organization (WHO) is providing scientific advice and decision-making tools that can help countries take action to improve nutritional health.

10 facts on nutrition by WHO

Available from: http://www.who.int/features/factfiles/nutrition/facts/en/index.html

1. Malnutrition, in all forms, is a major contributor to disease and early deaths for

mothers and children. Undernutrition, including vitamin and mineral deficiencies,

contributes to about one third of all child deaths, and impairs healthy development and life-long productivity. At the same time, growing rates of overweight are linked to a rise in chronic diseases.

2. A key indicator of chronic malnutrition is stunting - when children are too short for

5 children globally are stunted, according to 2011 figures, resulting from not enough food, a vitamin- and mineral-poor diet, inadequate child care and disease. As growth slows down, brain development lags and stunted children learn poorly. Stunting rates among children are highest in Africa and Asia. In Eastern Africa 42% were affected as of 2011.

3. Wasting and bilateral oedema are severe forms of malnutrition - resulting from acute food shortages and compounded by illness. About 1.5 million children die annually due to

wasting. Rising food prices, food scarcity in areas of conflict, and natural disasters diminish household access to appropriate and adequate food, all of which can lead to wasting.

4. Essential vitamins and minerals in the diet are vital to boost immunity and healthy

development. Vitamin A, zinc, iron and iodine deficiencies are primary public health

concerns. About 2 billion people are affected by inadequate iodine nutrition worldwide. More than one third of preschool-age children globally are vitamin A deficient. Vitamin A deficiency is the leading cause of preventable blindness in children.

5. Maternal undernutrition, common in many developing countries, leads to poor fetal

development and higher risk of pregnancy complications. Together, maternal and child

undernutrition account for more than 10% of the global burden of disease.

6. For healthier babies, WHO recommends exclusive breastfeeding for six months,

introducing age-appropriate and safe complementary foods at six months, and continuing breastfeeding for up to two years or beyond. Worldwide, about 20% of deaths

among children under-five could be avoided if these feeding guidelines are followed. Appropriate feeding decreases rates of stunting and obesity and stimulates intellectual development in young children.

7. Nutritional problems in adolescents start during childhood and continue into adult life. Anaemia is a key nutritional problem in adolescent girls. Preventing early pregnancies and assuring adequate intakes of essential nutrients for developing girls can reduce maternal and child deaths later, and stop cycles of malnutrition from one generation to the next. Globally, anaemia affects 42% of pregnant women.

8. The rise in overweight and obesity worldwide is a major public health challenge. People of all ages and backgrounds face this form of malnutrition. As a consequence, rates of diabetes, cardiovascular disease and other diet-related conditions are escalating worldwide.

9. Nutrition information is required to identify the areas where assistance is most needed. WHO released international child growth standards that provide benchmarks to compare children's nutritional status within and across countries and regions. Also, a nutrition

6 landscape information system, developed by WHO and partners, provides country profiles on key nutrition indicators and affecting factors such as food, health and care.

10. Science has moved forward, and evidenced-based actions that will improve nutritional

health - particularly for the most vulnerable - are known. In response, WHO and partners

are working together to provide scientific advice to countries, as well as user-friendly, web-based tools. These concerted efforts are aimed to stimulate policies and interventions that will save lives.

Healthy nutrition guidelines

Historically, dietary guidelines were nutrient-based. Food-based dietary guidelines (FBDG) developed to facilitate the teaching of healthy eating and nutrition to population groups. FBDG focus on foods, rather than nutrients and are intended for use by the general public. They are designed to be understandable to most consumers. FBDG are designed to be appropriate to each population group; they may be country, age, or culturally specific. The FAO report on the development of the FBDG is available on the website (www.fao.org.). These concepts are generic and recommended by FAO. Country-specific concepts are developed. The main recommendation in FBDG of different countries is that a healthy nutrition is possible only by eating a variety of different foods to maintain the required balance of nutrients.

A healthy diet should include:

 Meals based on starchy foods, such as bread, pasta, rice and potatoes – including high fibre varies where possible.

 Plenty of fruit and vegetables – at least 5 portions of a variety a day.

 Moderate amounts of milk and dairy products – choose low-fat options where possible.  Moderate amounts of foods that are good sources of protein such as meat, fish, eggs, beans

and lentils.

 Low amounts of foods that contain large amounts of fats or sugar.

The WHO Regional Office for Europe is committed to promoting an integrated approach to health promotion and disease prevention. The countrywide integrated noncommunicable disease intervention (CINDI) programme has identified food and nutrition policy as central to the prevention and control of noncommunicable diseases. The CINDI dietary guide was produced as the result of collaboration between the WHO CINDI programme and the WHO programme for nutrition policy, infant feeding and food security. This dietary guide has been prepared to assist

7 CINDI member countries in the development of policies and programmes that foster food consumption patterns that are healthy and consistent with local conditions and culture. This guide demonstrates that a healthy diet is based mainly on foods of plant origin, rather than animal origin. It also focuses on the need to provide information on the link between health and diet for the most vulnerable groups in society, notably people with low incomes.

Twelve steps to healthy eating by CINDI Dietary Guide

(Reference: WHO Regional Office for Europe, EUR/00/5018028. 2000)

1. Eat a nutritious diet based on a variety of foods originating mainly from plants, rather than animals.

2. Eat bread, grains, pasta, rice or potatoes several times a day.

3. Eat a variety of vegetables and fruits, preferably fresh and local, several times per day (at least 400g per day)

4. Maintain a body weight between the recommended limits (BMI=20-25 kg/m2) by taking moderate levels of physical activity, preferably daily.

5. Control fat intake (not more than 30% of daily energy) and replace most saturated fats with unsaturated vegetable oils or soft margarines.

6. Replace fatty meat and meat products with beans, legumes, lentils, fish, poultry or lean meat. 7. Use milk and dairy products (kefir, sour milk, yoghurt and cheese) that are low in both fat and

salt.

8. Select foods that are low in sugar, and eat refined sugar sparingly, limiting the frequency of sugary drinks and sweets.

9. Choose a low-salt diet. Total salt intake should not be more than one teaspoon (6g) per day, including the salt in bread and processed cured and preserved foods. (Salt iodization should be universal where iodine deficiency is endemic.)

10. If alcohol is consumed, limit intake to no more than 2 drinks (each containing10g of alcohol) per day.

11. Prepare food in a safe and hygienic way. Steam, bake, boil or microwave to help reduce the amount of added fat.

12. Promote exclusive breastfeeding and the introduction of safe and adequate complementary foods from the age of 6 months while breastfeeding continues during the first years of life.

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Health problem due to Junk food

Due to the high levels of calories and trans fats present in junk food, there is an accumulation of fat as well as development of insulin resistance which is an early indication of diabetic disorders. In time this weight gain could lead to other disorders such as, high blood pressure, cardiac problems, increased cholesterol levels, blockage in arteries, depression, loss of muscle mass and so on. The marketing of junk foods and non-alcoholic beverages with a high content of fat, sugar or salt reaches children throughout the world. Dr. Ala Alwan, Assistant Director General, WHO, said that efforts must be made to ensure that children everywhere are protected against the impact of such marketing and given the opportunity to grow and develop in an enabling food environment - one that fosters and encourages healthy dietary choices and promotes the maintenance of healthy weight.

Conclusion. A healthy balanced nutrition means getting the right types and amounts of foods and drinks to supply nutrition and energy for maintaining body cells, tissues, and organs, and for supporting normal growth and development. A well-balanced nutrition provides enough energy and nutrition for optimal growth and development. To ensure healthy nutrition, firstly, need to know how many calories we should consume every day; secondly, what size portions we should eat and which are the healthy choices from each food group. Also, read nutrition labels on all foods. This will help us know what kind of fats, and how much, the food contains.

2. Body mass evaluation methods. Human energy requirements

2.1 Body mass evaluation methods

Normal body weight can affect the happiness and enjoyment of life. Having a proper body weight is important to good nutrition. An individual should not be too fat or too thin, but how much weight is too much and how little is not enough? One the most common method for evaluating the appropriate weight is the calculation of body mass index (BMI).

Body mass index (BMI). The indicator of weight adequacy in relation to height of older children, adolescents and adults. It is calculated as weight (in kilograms) divided by height (in meters), squared. The acceptable range for adults is 18.5 to 24.9, and for children it varies with age. If the BMI of an adult (except a pregnant woman, sportsman, children, and elderly people) is: below 18.5, they are underweight; 18.5 – 24.99, they are within the normal range; 25.0 – 29.99, they are probably overweight; over 30, they are probably obese.

9 Numerous studies have documented a U- or J-shaped association between BMI and mortality, such that increased mortality rate is associated with relatively low and high BMI values (Caballero, 2007; Petursson et al., 2011). In recent years, there has been increasing discussion over which measure of overweight and obesity is the best indicator to identify those individuals who are at increased cardiovascular risk (Lee et al., 2008; Schneider et al., 2077; Parks et al., 2009; Kaess et al., 2010). The most popular are measurements of height and weight, preferably expressed as the BMI. Also, this measure is used by the WHO to define severity of overweight and obesity across population. Epidemiological studies have revealed that abdominal fat accumulation is an important predictor of cardiovascular risk (Parks et al., 2009; Kaess et al., 2010). The measurement of the waist circumference (WC) is mostly used for defining of central obesity, but this measurement has been criticized for not taking into account differences in body height (Ashwell et al., 1996). Recently performed studies found that waist-to-height ratio (WHtR) may be used as marker of body fat centralization, and could be a better predictor of cardiovascular risk (Schneider et al., 2077; Parks et al., 2009; Kaess et al., 2010; Luksiene et al. 2011). Some investigators have shown that the strength of the associations between anthropometric indexes and cardiovascular risk is population-dependent (Molarius et al, 1998).

Waist circumference. Waist circumference can be measured by placing a cloth tape measure around the smallest part of the waist while standing relaxed. The measurement of waist circumference provides insight to increased risk of obesity-related illness due to the location of excess fat. By WHO waist circumference cut-offs and risk of associated metabolic complications: increased (≥ 94 cm for men and ≥ 80 cm for women); substantially increased (≥ 102 cm for men and ≥ 88 cm for women). By NCEP-ATPIII recommendations waist circumference ≥ 102 cm for men and ≥ 88 cm for women is a risk factor for noncommunicable diseases (NCEP-ATPIII, 2002). By International Diabetes Federation (IDF) recommendations waist circumference ≥ 94 cm for men and ≥ 80 cm for women is a risk factor for noncommunicable diseases (Zimmet P et al., 2005).

Waist to Hip Ratio (WHR) is increasingly being used by doctors in preference to BMI as a better measurement of the risk of obesity and cardiovascular disease. Waist hip ratio >0.9 for men and >0.8 for women is a risk factor for all noncommunicale diseases.

Android fat distribution describes the distribution of human adipose tissue mainly around the trunk

and upper body, in areas such as the abdomen, chest, shoulder and nape of neck. This pattern may lead to an "apple-shaped" or central obesity, and is more common in males than in females. Android obesity places an individual at greater risk for high blood pressure, metabolic syndrome, type 2

10 diabetes mellitus, high cholesterol, coronary artery disease and premature death.

Gynoid fat distribution describes the fat around the hips and bottom, causing a "pear-shape". In

other cases, an ovoid shape forms which does not differentiate between men and women. In Asians and Asian Indians there is increased visceral fat for same waist circumference as compared to Americans and Africans.

Skinfold measurement. Body fat percentage can be estimated by using callipers to measure skinfold thickness at various body sites on the body. The most commonly used sites are subscapular, suprailiac, biceps, and triceps. Total skinfolds from these sites can be substituted into prediction equations to give an estimate percents of fatty mass. The most commonly used equations are those derived by Durnin and Wormesley (1974). Equations that are appropriate for specific ages and ethnic groups are available. The sum of the skinfolds taken at various sites can then be converted to calculate percents of body fat. Fat is an average of 13-16% of body weight for men and 20-24% of women. This technique is fairly quick and can be accurate. However, it is important to find a trained technician to make the measurements. If the measurements are not taken correctly or an incorrect formula is applied, erroneous values can result.

Changes in life styles, nutrition and ethnic composition of populations lead to changes in the distribution of body dimensions (e.g. the obesity epidemic), and require regular updating of anthropometric data collections.

2.2 Human energy requirements

Human energy requirements are estimated from measures of energy expenditure plus the additional energy needs for growth, pregnancy and lactation. Recommendations for dietary energy intake from food must satisfy these requirements for the attainment and maintenance of optimal health, physiological function and well-being.

Human beings need energy for the following:

 Basal metabolism. This comprises a series of functions that are essential for life, such as cell function and replacement; the synthesis, secretion and metabolism of enzymes and hormones to transport proteins and other substances and molecules; the maintenance of body temperature; uninterrupted work of cardiac and respiratory muscles; and brain function. The amount of energy used for basal metabolism in a period of time is called the basal metabolic

11 rate (BMR), and is measured under standard conditions that include being awake in the supine position after ten to 12 hours of fasting and eight hours of physical rest, and being in a state of mental relaxation in an ambient environmental temperature that does not elicit heat-generating or heat-dissipating processes. Depending on age and lifestyle, BMR represents 45 to 70% of daily total energy expenditure, and it is determined mainly by the individual’s age, gender, and body size and body composition.

 Metabolic response to food. Eating requires energy for the ingestion and digestion of food, and for the absorption, transport, interconversion, oxidation and deposition of nutrients. These metabolic processes increase heat production and oxygen consumption, and are known by terms such as dietary-induced thermogenesis, specific dynamic action of food and thermic effect of feeding. The metabolic response to food increases total energy expenditure by about 10% of the BMR over a 24-hour period in individuals eating a mixed diet.

 Physical activity. This is the most variable and, after BMR, the second largest component of daily energy expenditure. Humans perform obligatory and discretionary physical activities. Obligatory activities can seldom be avoided within a given setting, and they are imposed on the individual by economic, cultural or societal demands. The term "obligatory" is more comprehensive than the term "occupational" that was used in the 1985 report (WHO, 1985) because, in addition to occupational work, obligatory activities include daily activities such as going to school, tending to the home and family and other demands made on children and adults by their economic, social and cultural environment.

Energy for the metabolic and physiological functions of humans is derived from the chemical energy bound in food and its macronutrient constituents, i.e. carbohydrates, fats, proteins and ethanol, which act as substrates or fuels. After food is ingested, its chemical energy is released and converted into thermic, mechanical and other forms of energy (Human energy requirements: Report of a Joint FAO/WHO/UNU Expert Consultation, 2001).

2.3 Calculation of energy requirements

Energy requirement is the amount of food energy needed to balance energy expenditure in order

to maintain body size, body composition and a level of necessary and desirable physical activity consistent with long-term good health. This includes the energy needed for the optimal growth and development of children, for the deposition of tissues during pregnancy, and for the secretion of milk during lactation consistent with the good health of mother and child.

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The recommended level of dietary energy intake for a population group is the mean energy

requirement of the healthy, well-nourished individuals who constitute that group. People waste different amount of energy in different fields of theirs activity. Body weight maintenance over a period time occurs (BMI 18.5 - 24.99 kg/m2) then:

ENERGY EXPENDITURE = ENERGY INTAKE

ENERGY EXPENDITURE = BMR + TEF + Physical activity

The basal metabolic rate (BMR) or basal energy expenditure (BEE) is a measurement of the energy expended for maintenance of normal body functions and homeostasis plus a component for activation of the sympathetic nervous system, and for regulation body temperature. It comprises approximately 60-75% of daily energy intake in sedentary individuals.

The thermic effect of food (TEF) is the result of energy expended to digest, transport, metabolize, and store food. On average TEF accounts for about 10% of daily energy expenditure and varies depending on the metabolic fate of the ingested substrate.

Physical activity (thermic effect of exercise) which is the most variable component of energy expenditure in individuals. Sedentary people, exercise may constitute approximately 15% of daily energy expenditure, whereas, an individual who regularly exercises may expend up to 30% of his or her total daily energy output in this manner (Table 1)

Table 1. Coefficient of physical activity level by Recommended Dietary Allowances for Lithuanian Population

Physical activity level

Characterization of work Coefficient of physical activity (C)

1 Light work and sedentary lifestyle (office workers, skilled

workers, students)

1.5 2 Moderate heavy work and sedentary lifestyle

(People with skilled management occupations - doctors, drives, teachers, lawyers, business men, saleswomen, etc.)

1.7

3 Heavy work and active lifestyle

(People with skilled sales and service occupations – light industrial workers, managers, surgeons, housewives, etc.)

2.0

4 Very heavy work (people with occupations to processing and

manufacturing (farmers, builders) and sportsmen.

>2.0

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By Recommended Dietary Allowances for Lithuanian Population (2000) DAILY ENERGY REQUIREMENT (DER) equal the Basal Energy Expenditure (BEE) multiplied by the coefficient

of physical activity. Coefficient of physical activity (C) range from 1.5 to over 2 (average 2.2) (see Table 1).

DER = BEE x C

FOR MEN, BEE = 65.4 + (13.7 x W) + (5.0 x H) – (6.8 x A)

FOR WOMEN, BEE = 655 + (9.6 x W) + (1.8 x H) – (4.7 x A)

Calculation of energy metabolism according to data of time keeping.

According to the data of time keeping and tables given of our energy consuming in kilocalories per minute for 1 kg of body weight is possible to calculate the quantity of energy metabolism of a man in 24 hours or another period.

Three steps for calculation:

1) A quantity of energy expenditure is calculated by multiplying the duration of separate works in minutes by calorimetrical equivalents (in kcal per minute for 1 kg body weight).

2) Obtained results are summed up and multiplied by body's weight in kg.

3) Taking to account the precision of the time keeping, obtained results can be increased at 5-10%.

Comparable coefficient of efficiency is calculated knowing the data of energy metabolism about the work of different intensity or the same work done by different persons. In Table 2 shown the example of calculation of energy metabolism according to the data of time keeping

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Table 2 The example of calculation of energy metabolism according to the data of time keeping Kinds of activities during day kcal/min/1kg Duration,

min. Total expenditure energy (kcal/min/1kg) Sleeping (9 hours) 0.0155 540 8.37 Bed making 0.0329 5 0.16 Morning exercises 0.0648 15 0.97 Personal hygiene 0.0329 20 0.66

Putting on and taking off clothes 0.0281 10 0.28

Eating while sitting 0.0236 60 1.42

Going by buss or by car 0.0267 60 1.60

Walking at 6 km/h 0.0714 60 4.28

Running at 9 km/h 0.1420 30 4.26

Rest while laying 0.0183 30 0.55

Working with PC 0.0333 120 3.40

Mental work while sitting (6 lessons x 45 min)

0.0243 315 7.65

Oral reading (loud) 0.0250 15 0.38

House work 0.0573 90 5.16

Rest while sitting 0.0229 60 1.37

Wash by hand 0.0511 10 0.51

TOTAL 1440 32.65

kcal/min/kg x weight, kg (weight = 70 kg)

32.65 x 70 = 2285.5

+ 10% of Total EE 2285.5 x 0.1 = 228.55

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2.4 Calculation of the quantity of calories in the food

Your body is in a state of caloric balance when food intake in calories is exactly equal to energy expenditure and elimination through basal metabolism, physical activity and calories lost in excreta (excrement, sweat, etc.). In this state no body weight gain or loss will occur.

Food has energy potential, which is measured in calories. Since one calorie is too small unit to be convenient, nutritionists use “kilocalorie” (kcal) as a measure. One kilocalorie is equal to 1000 small calories. One kilocalorie (1 kcal) is the amount of heat required to raise the temperature of one kilogram of water one degree Celsius.

1 kcal = 4.19 kJ

Caloricity of nutrients is not equal. One gram of carbohydrates take to our organism 4.1 kcal, one gram of fats – 9.3 kcal and one gram of protein – 4.1 kcal.

Calculation of the theoretic calorific capacity (TCC) of the food.

You must record the foods you eat and their nutritional value – how many grams of carbohydrates, fats and proteins they contain by use the Table of nutritive value of the edible part of foods. The quantity of grams of carbohydrates and proteins are multiplied to 4.1 and quantity of grams of fats – to 9.3, and the sum of calories shows the TCC of the used food.

Estimation of real or in fact calorific capacity of the dish at the laboratory is produced after removes from the dish the parts of the food which are not eatable. Products which are separate and their composition are showed in the Tables of nutritive value, and are possibility to weight them separately – their calorific capacity is calculated as theoretical.

Estimation of Netto calorificity. The calories of the dish in the plate ate called as brutto calories.

But not all nutrients are used by your organism. Some of them are excreted from the organism without any changes. The quantity of calories which are resorbed and used for the energetically purposes are called as netto calories.

The coefficients for estimation of netto caloricity are different: for vegetable foods – 85% are resorbed, for animal foods – 95%, and for various foods - 90% are resorbed.

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3. Proteins. Classification of amino acids. Sources of protein in diet.

Proteins are essential for numerous structural and functional purposes and are essential for growth and repair of the body. In adults approximately 16% of body weight is protein. 43% of this is muscle, 15% skin and 16% blood.

Function

Structural. Protein is important for the structure of the body and about half of the body's protein is

in structural tissues such as skin and muscle. These structural proteins are collagen (25% of the body's protein), actin, and myosin.

Transport. Proteins act as transport carriers in the blood and body fluids for many molecules and

nutrients, e.g. haemoglobin, lipoproteins.

Hormonal. Hormones and peptides are proteins or amino acid chains, e.g. insulin, pancreatic

polypeptide.

Enzymes. All enzymes are proteins. Extracellular enzymic proteins include the digestive enzymes,

e.g. amylase. Intracellular enzymes are involved in metabolic pathways, e.g. glycogen synthestase.

Immune function. Antibodies are protein molecules. Proteins are also involved in the acute phase

response to inflammation.

Buffering function. The protein albumin acts as a buffer in the maintenance of blood pH. Energy. Protein provides approximately 10-15% of the energy in the diet (1g protein=4 kcal).

Structure

Amino acids form peptide chains of various lengths from two amino acids (dipeptide), 4-10 peptides (oligopeptides), more than 10 amino acids (polypeptides).

Indispensable (essential) amino acids. Some amino acids can be synthesized by the body but others must be supplied by the diet (Table 3). These are known as indispensable or essential amino acids; there are eight essential amino acids. Some amino acids are only essential in specific circumstances. In childhood seven other amino acids are essential that are not essential in adults (arginine, histidine, cysteine, glycine, tyrosine, glutamine, proline). These amino acids are essential in children because they are required in amounts larger than can be synthesized because of high demand, immature biological pathways, or a combination.

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Table 3 Indispensable (essential) amino acids and nonessential amino acids Indispensable (essential) AA

(must be supplied by the diet)

Nonessential AA (synthetize by body)

Amino acid (AA) Daily intake (g) Amino acid (AA) Daily intake (g)

Tryptophan (Trp) 1 *Histidine (His) 1.5-2

Leucine (LEU) 4-6 *Arginine (Arg) 5-6

Isoleucine(Ile) 3-4 *Cysteine (Cys) 2-3

Valine (Val) 3-4 *Tyrosine (Tyr) 3-4

Threonine (Thr) 2-3 Alanine (Ala) 3

Lysine (Lys) 3-5 Serine (Ser) 3

Methionine (Met) 2-4 Glutamic acid (Glu) 16

Phenylalanine (Phe) 2-4 Asparagine (Asn) 6

*Proline (Pro) 5

*Glycine (Gly) 3

*Glutamine 3

Aspartic acid (Asp) 3 *In childhood 7 AA are essential that are not essential in adults.

Requirement

Definition of protein requirement by WHO. Protein requirement by WHO can be defined as: the

lowest level of dietary protein intake that will balance the losses of nitrogen from the body, and thus maintain the body protein mass, in persons at energy balance with modest levels of physical activity, plus, in children or in pregnant or lactating women, the needs associated with the deposition of tissues or the secretion of milk at rates consistent with good health.

Proteins are classed as having high biologic value on the basis of their ability to supply all the essential amino acids required for the formation of body tissues, enzymes, and hormones. At the top of the list of proteins of high biologic value is egg protein. Close to it ranks the protein of milk (mainly casein, with smaller quantities of albumin). Fish, meat and poultry proteins are very high in the scale of biologic value. Of distinctly lower value are the plant proteins such as those of wheat, corn, rice, beans, and nuts. These proteins may contain the necessary amino acids, but in each one

18 of them one or more of the essential amino acids are present in such inadequate amounts that entire protein is in low biologic value, when it represents the only source of amino acids in the diet. Such incomplete plant proteins can be supplemented with other foods supplying the missing amino acids in order to provide good nutrition. The plant proteins are of lower biological value than animal proteins, so this is important in vegan diets. By combining foods with low biological value it is possible to provide all essential amino acids in the diet. For example, the limiting amino acid in wheat is lysine and in pulses it is methionine. A diet combining wheat products such as bread with pulses will provide all the essential amino acids.

Recommended protein allowance provides 0.8 g of protein per kilogram body weight for healthy persons with adequate caloric intake, normally vigorous, and living in a temperate climate. Increased allowances are during lactation, pregnancy, for children and for elderly (70 years

and over) age:

 3 years 1.2 – 1.0 g/kg body weight per day;  4 - 6 years 0.9 – 1.0 g/kg body weight per day;  7 - 18 years 0.8 – 0.9 g/kg body weight per day,  over 70 years 0.9-1.0 g/kg body weight per day.

Essential amino acid requirements per day: from 17 to 160 mg/kg body weight for children, from 4 - 40 mg/kg body weight for adults.

Deficiency

Protein energy malnutrition (PEM) is a major cause for concern in developing countries. These include immune - compromised individuals (e.g. AIDS), anorexia, and cancer patients with cachexia. Mild PEM is fairly common amongst surgical or elderly hospital patients. Protein deficiency can also occur as the results of increases losses in renal disease, increases catabolism in trauma, burn or sepsis, or malabsorption. Protein deficiency results in muscle wasting stunted growth, poor wound, healing, and susceptibility to infection, oedema, and fatty liver.

Kwashiorkor is an acute form of childhood protein-energy malnutrition characterized by oedema,

irritability, anorexia, ulcerating dermatoses, enlarged liver with fatty infiltrates. Kwashiorkor may develop after a mother weans her child from breast milk, replacing it with a diet high in carbohydrates, especially starches, but deficient in protein. The insufficient protein consumption, but with sufficient calorie intake, distinguishing it from marasmus. Kwashiorkor cases occur in areas of famine or poor food supply. Cases in the developed world are rare.

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Marasmus is a form of severe malnutrition characterized by energy deficiency. A child with

marasmus looks emaciated. Body weight may be reduced to less than 80% of the average weight that corresponds to the height. The malnutrition associated with marasmus leads to extensive tissue and muscle wasting, as well as variable oedema. Other common characteristics include dry skin, loose skin folds hanging over the buttocks and etc.

Sources of dietary protein

High biological value proteins are from animal sources, e.g. eggs, meat, milk, dairy products, and fish. If one or more essential amino acids are not present in a protein it will have low biological value. Generally plant proteins are of low biological value. The main sources of protein are soy (37 g/100g), beans and lens (22.8 g/100g), meat (14-25 g/100g); fish (15-22 g/100g), cheese (15-30 g/100g), eggs (13-14 g/100g).

4. Fats and fatty acids, their classification. Sources of fats and

cholesterol in diet.

Fats are often referred to as lipids. Lipids are described by chemists as substances that are poorly soluble or insoluble in water but are soluble in organic solvents. Fat is the term most often used when discussing foods and lipids metabolism. Over 90% of dietary fats are triglycerides (triacylglycerol’s); other types of fat include cholesterol, phospholipids, sterols, and carotenoids.

Function

The functions of fat in the diet are:

• Energy source-fat provides 9 kcal (37 kJ) per gram. • Fat provides essential fatty acids.

• Fat is a carrier for fat soluble vitamins A, D, E, and K.

• Increase palatability by improving taste perception and appearance of food.

• Some fats are important constituents of cell membranes and can be converted to biologically active compounds such as steroid hormones, interleukins, thromboxanes, and prostaglandins. • Cholesterol is converted to bile acids, which are important in digestion.

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4.1 Nomenclature of fatty acids

Fatty acids are carbon molecules with a methyl group at one end and a carboxyl acid at the other. They can have chains of 4 - 22 carbon molecules although most have 16 - 18. Triglycerides have glycerol backbone to which is attached three fatty acids. The type of fatty acid attached to the glycerol molecule determines its physical properties, nutritional function, and physiological function.

Fatty acids have a common name, e.g. linoleic acid, a systematic name, and a notational name. The systematic name reflects the number of carbon atoms, and the number of double bonds, so that linoleic acid becomes octadecadienoic acid. This represents 18 carbons (octadeca-) and two double bonds (di-). The notational name for linoleic acid is 18:2 n-6 or 18:2 omega 6; again this represents 18 carbon atoms and two double is now also represented. The position is relative to the methyl (or omega) end of the carbon chain. Linoleic acid has its first double bond between the sixth and seventh carbons. Common names and notational names (Abbreviation) are shown in Tables 4-7.

Saturated fatty acids (SFA). Saturated fatty acids contain carbon atoms linked by single bonds and hydrogen on all available arms. They have a relatively high melting point and tend to be solid at room temperature. SFA are obtained from animal storage fats and their products, e.g. meat fat, lard, milk, butter, cheese, and cream. Fats from plant origin tend to be unsaturated with the exception of coconut oil and palm oil. Some manufactured margarines and spreads contain significant amounts of SFA. Plasma low density lipoprotein (LDL) cholesterol, and plasma total cholesterol, tends to be raised by SFA. High intakes of SFA are associated with atherogenesis and cardiovascular disease.

Table 4 Common saturated fatty acids, their abbreviation and typical sources Trivial name Abbreviation Typical source

Butyric C4:0 Dairy fat

Caproic C6:0 Dairy fat

Caprylic C8:0 Dairy fat, coconut, palm kernel oils Capric C10:0 Dairy fat, coconut oil , palm kernel oil Lauric C12:0 Coconut oil (49%), palm kernel oil(50%)

Myristic C14:0 Dairy fat, coconut oil (17%), palm kernel oil (16%) Palmitic C16:0 Most fats and oils: (palm oil (45%), pork fat (25%);

chicken fat (23%)

Stearc C18:0 Most fats and oils: cacao butter (35%); beef lard (21%), pork fat (12%)

Arachidic C20:0 Most fats and oils

21 Monounsaturated fatty acids (MUFA). MUFA contain only one double bond and are usually liquid (oil) at room temperature. Oleic acid is the most common MUFA and it is present in considerable quantities in both animal and plant sources. Olive oil and rape seed oil are the most concentrated dietary sources of MUFA. MUFA are present in many foods including meat fat and lard. Dietary MUFA does not raise plasma cholesterol and lowers LDL cholesterol without a detrimental effect on high density lipoprotein (HDL) cholesterol.

Table 5 Some common cis-monounsaturated fatty acids (MUFA) in food fats and oils Common name Abbreviation Typical source

Palmitoleic C16:1 Marine oils, macadamia oils, most animal and vegetable oils

Oleic C18:1 All fats and oils, especially olive oil (71%), canola oil (64%), pork fat (45%), chicken fat (41%)

% of the total fatty acids in product

Polyunsaturated fatty acids (PUFA). PUFA contain two or more double bonds and are liquid at room temperature. They are easily oxidized in foods and in the body. PUFA are involved in the metabolism of cholesterol, are components of phospholipids in cell membranes, and are precursors of biologically active compounds such as prostaglandins, interleukins, and thromboxane’s. Therefore they have vital roles in the immune response, blood clotting, and inflammation. PUFA are derived from the essential fatty acids linoleic acid (n-6 or omega 6) and α-linoleic acid (n-3 or omega 3) and are divided into omega 3 (or n-3) or omega 6 (n-6) groups of PUFA.

PUFA occur as cis or trans forms depending on the way the hydrogen atoms are arranged. In cis formation the hydrogen atoms are bonded to either end of the double bond on the same side. In the

trans form the hydrogen atoms are on opposite side. Most naturally occurring fats are in the cis

form. The nutritionally important of n-6 and n-3 PUFA shown in Tables 6 and 7.

Table 6 Nutritionally important n-6 polyunsaturated fatty acids (PUFA) Common name Abbreviation Typical source

Linoleic acid 18:2 n-6 (LA) Most vegetable oils, especially, sunflower oil (68.2%), canola oil (18.7%), chicken fat (18.9%)

γ-linolenic 18:3 n-6 (GLA) Evening primrose, borage and blackcurrant seed oils.

Arachidonic acid 20:4 n-6 (AA) Animal fats, liver, egg lipids, fish oil % of the total fatty acids in product

22

Table 7 Nutritionally important n-3 polyunsaturated fatty acids (PUFA) Common name Abbreviation Typical source

α-linolenic acid 18:3 n-3 (ALA) Flaxseed oil, canola oil (9.2%), soybean oil (7.8%)

Stearidonic acid 18:4 n-3 (SDA) Fish oils, genetically enhanced, soybean oil, blackcurrant seed oil

Eicosapentaenoic acid 20:5 n-3 (EPA) Fish (16%), especially oily fish (salmon, herring, anchovy, smelt and mackerel) Docosapentaenoic acid 22:5 n-3 (n-3 DPA) Fish, especially oily fish (salmon, herring,

anchovy, smelt and mackerel)

Docosahexaenoic acid 22:6 n-3 (DHA) Fish (11%), especially oily fish (salmon, herring, anchovy, smelt and mackerel) % of the total fatty acids in product

Trans fatty acids (TFA). Hydrogen is added to unsaturated fatty acids to make them more solid when manufacturing some food products such as vegetable spreads (margarine); this process is known as hydrogenation. Hydrogen atoms are attached to the carbon chain; the number of hydrogen atoms determines the degree of saturation (with hydrogen atoms) of the fatty acid. A fatty acid with hydrogen atoms on every arm is said to be „saturated“.

TFA from commercial partially hydrogenated vegetable oils (PHVO) increase coronary heart disease (CHD) risk factors and CHD events – more so than had been thought in the past. There also is probable evidence of an increased risk of fatal CHD and sudden cardiac death in addition to an increased risk of metabolic syndrome components and diabetes. So by the WHO and FAO experts acknowledged the current recommendation of a mean population intake of TFA of less than 1%E may need to be revised and need to remove partially hydrogenated fats and oils from the human food supply.

Recommendations for saturated fatty acids (SFA) by the Report of an experts consultation Food

and Agriculture Organization of the United Nation, „Fats and fatty acids in human nutrition“ (2010).

Individual SFA have different effects on the concentration of plasma lipoprotein cholesterol fractions. For example, lauric (C12:0), myristic (C14:0) and palmitic (C16:0) acids increase LDL cholesterol whereas stearic (C18:0) has no effect.

23 There is convincing evidence that:

 Replacing SFA (C12:0–C16:0) with PUFA decreases LDL cholesterol concentration and the total/HDL cholesterol ratio. A similar but lesser effect is achieved by replacing these SFA with MUFA.

 Replacing dietary sources of SFA (C12:0–C16:0) with carbohydrates decreases both LDL and HDL cholesterol concentration but does not change the total/HDL cholesterol ratio.  Replacing SFA (C12:0–C16:0) with trans fatty acids (TFA) decreases HDL cholesterol and

increases the total /HDL cholesterol ratio.

Therefore, it is recommended that SFA should be replaced with PUFA (n-3 and n-6) in the diet and the total intake of SFA not exceed 10% of total energy intake (E).

The determination of intake of MUFA is calculated by difference

MUFA = Total fat intake (%E )– SFA (E%) – PUFA (E%) – TFA (%E).

Therefore, the MUFA intake resulting may cover a wide range depending on the total fat intake and dietary fatty acid pattern.

4.2 Cholesterol

Cholesterol and cholesterol ester (cholesterol to which a fatty acid is attached) are only found in animal foods. Phytosterols are found in plant foods. Cholesterol has structural roles in lipoproteins and membranes and is a precursor for bile acids, steroid hormones, and vitamin D. Dietary cholesterol has little influence on plasma levels as most circulating cholesterol is endogenous. For a person of about 68 kg, typical total body-cholesterol synthesis is about 1 g (1,000 mg) per day, and total body content is about 35 g, primarily located within all the membranes of all the cells of the body. Typical daily dietary intake of additional cholesterol recommended by WHO is 200–300 mg. Reduction of intake of saturated fat and dietary cholesterol (<200 mg/d) results in lower plasma total cholesterol levels.

Major dietary sources of cholesterol include meat offal (liver, brain, lungs, and kidneys), cheese, egg yolks, beef, pork, poultry, fish, and shrimp. Low cholesterol includes skinless poultry, skimmed milk and dairy products. Cholesterol frees all plant foods (vegetables, fruits, cereals, pasta, rice, vegetables oils etc.) and also egg white, sugar.

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5. Carbohydrates and their classification. Insoluble and soluble fibre,

their impact on health. Sources of carbohydrates in diet.

Carbohydrates are the most significant source of energy in the diet. In developing countries up to 85% of energy in the diet is provided by carbohydrate; this figure is as low as 40% in some developed countries. The relationship between dietary carbohydrates and fat is usually reciprocal: diets rich in fat will have low levels of carbohydrates and vice versa.

Function

Structural. They are an integral part of cell walls of plant and microorganisms (cellulose, lignin). Protective. Many antigens are glycoprotein (which contains oligosaccharide) in nature and give

immunological properties to the blood. Heparin is a polysaccharide (carbohydrate) which acts as anticoagulant and prevents intravascular clotting.

Catalytic. Indirectly, carbohydrates are important for enzymatic catalysis. Some enzymes are

glycoproteins.

Hormone. Many hormones like FSH (Follicular Stimulating Hormone, which takes part in

ovulation in females) and LH (Leuteinizing Hormone) are glycoprotein and help in reproductive processes.

Energy. Carbohydrates are the main energy source of cells in the various processes because the

energy released during oxidation is used for the synthesis of ATP, vital functions to ensure heat. Glucose is used as source for storage of energy such as in form of glycogen in animals and starch in plants.

Structure and classification

The empirical formula for carbohydrates is Cx(H20). Glucose is the simplest carbohydrate (C6H12O6). Simple carbohydrates (monosaccharides) can combine to form disaccharides. e.g. sucrose (C12H22011) from two disaccharides, oligosaccharides. e.g. raffinose which is formed from 3-11 monosaccharides, or polysaccharides, which form from 12 or more saccharides. e.g. starches. Carbohydrates that can be digested and absorbed in the small intestines. Plant polysaccharides that cannot be digested (non-glycaemic) are referred to as fibre or non-starch polysaccharides.

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Sugars (mono-and disaccharides)

Monosaccharides. Monosaccharides are the simplest carbohydrates in that they cannot be hydrolysed to smaller carbohydrates. They are aldehydes or ketones with two or more hydroxyl groups. Monosaccharides include glucose, fructose, and galactose. About 65% absorbed by the intestinal tissue glucose is oxidized (used to create energy), about 30% - is used in the synthesis of fat and about 5% - for glycogen synthesis. These proportions are changing; it depends on the body's physiological status, age, etc. Glucose - versatile, easily accessible source of energy for all body cells, it is “the main food of brain”. The adult human brain consumes about 120g of glucose per day. Human blood glucose levels - from 3.3 to 5.5 mmol/l. Low blood glucose (hypoglycaemia) is one of the reasons that cause the sensation of hunger.

Fructose is found in honey, fruit, and vegetables. Fructose metabolism does not involve insulin (absorbed directly into the bloodstream during digestion), so people with diabetes easier to tolerate. Galactose is less sweet than glucose and found in dairy products, sugar beets, and etc.

Disaccharides. Disaccharides include surcose, lactose and maltose. The disaccharide, sucrose, is formed from two monosaccharides, glucose and fructose. Sucrose is the commonest disaccharide and is extracted from sugar beet or sugar cane. Table sugar is 99% sucrose and the major dietary source of disaccharide. Sucrose is hydrolysed into glucose and fructose. Lactose is found in milk and milk products. It is hydrolysed to glucose and galactose. Maltose is present in malted wheat and barley. Malt extract is used in brewing and in malted products.

Oligosaccharides. Raffinose, stachyose, and verbascose are oligosaccharides that are made of galactose, glucose, and fructose. They are found in legumes and seeds. Humans do not have the enzyme needed to digest them, but they may be fermented in the colon. Fructo-oligosaccharides and inulin have been shown to stimulate growth of the potentially beneficial bifidobacteria in the colon.

Polysaccharide

Starch is the main storage polysaccharide in plant cells and is found in large quantities in cereal grains, potatoes, and plantains. Starch is the largest source of carbohydrate in the diet. Starch consists of two glucose polysaccharides: amylose and amylopectin. The linkages between the glucose molecules are degraded by the action of α-amylase. Many factors affect the rate at which the linkages are degraded so that some starch are readily digested while others pass undigested into the colon. This has resulted in the classification of starches into rapidly digestible starch (RDS),

26 slowly digestible starch (SDS), and resistant starch (RS) (Table 8). Both RDS and SDS are digested in the small intestine while RS passes undigested into the colon where it is available for fermentation.

Table 8 Classification of starch

Class Glycaemic

response

Food source

Rapidly digestible starch (RDS) Large Cooked starchy cereals, warm potatoes Slowly digestible starch (SDS) Small Muesli, oats, pasta, legumes

Resistant starch (RS) None Unripe bananas, whole grains

Glycogen is another glucose polymer. Glycogen is a stored energy source, found in the liver and muscles of humans. The human body stores enough glycogen to provide sugar to blood for 24-36 hours during fasting.

Fibre - non-starch polysaccharide. Fibre can be classified as soluble (in water at pH=7.0) or insoluble and it is this classification that categorizes the function of these, polysaccharides. Insoluble fibre consists mainly of cellulose and some hemicelluloses. Insoluble fibre binds to water in the colon and swells. This stimulates peristalsis so increase transit time in the colon thereby reduces the risk of constipation and possibly reduces the risk of colon cancer. Soluble fibre blunts the response of blood glucose to ingestion. The reabsorption of bile acids is slowed by soluble fibre so increase cholesterol losses in faeces and reduce blood cholesterol levels. The main sources of soluble and insoluble fibre in the diet shown in Table 9.

Table 9 Dietary sources of soluble and insoluble fibre in the diet Soluble fibre Insoluble fibre

Apples Barley Citrus fruits Legumes Oats Pears Strawberries Beans Brown rice

Fruits with edible seeds Lentils Maize Oats Pulses Wheat bran Wholemeal breads Wholemeal cereals Wholemeal pasta Peas

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Recommended intakes

The FAO/WHO Expert Consultation on Carbohydrates in Human Nutrition recommended an optimum carbohydrate level of at least 55% of total energy intake (free sugars < 10%E), obtained from a variety of food sources, and noted that levels of carbohydrate consumption at or above 75% of total energy should be avoided because of the exclusion of adequate amounts of protein, fat, and other essential nutrients. Fibre is recommended that the adult diet contain 25 -30 g/d.

Glycaemic index (GI) and Glycaemic load (GL)

The glycaemic index (GI) is a method of ranking foods and carbohydrates based on their

immediate effect on blood glucose levels. The FAO/WHO in 1998 define the GI as “the incremental area” under the blood glucose response curve of one 50 g carbohydrate portion of a test food expressed as a percentage of response to the same amount of carbohydrate from a standard food taken by the same subject”. The standard carbohydrate is glucose that has a GI of 100. Foods with a high glycaemic index are readily absorbed and raised blood glucose quickly. Low glycaemic index foods are digested and absorbed slowly and raise blood glucose levels slowly. Foods are categorized into: low GI (55 or less); medium GI (56-69); high GI (70 or more).Table 10 presents the examples of low, medium and high GI foods.

Table 10 Examples of low, medium and high GI foods

Low GI (55 or less) Medium GI ( 56-69) High GI ( 70 or more)

Apples, oranges, pears, peaches; Beans, lentils;

Pasta (all types made from durum wheat);

Sweet potato (peeled and boiled) Sweet corn Porridge Honey Jam Shredded wheat Ice cream

Potatoes (peeled and boiled) Pitta bread

Couscous

Glucose

White and wholemeal bread Rice, cooked

Cornflakes Baked potato Mashed potato

The health benefit of a low GI diet include: (i) improved diabetic glucose control; (ii) improved risk factors for heart disease; (iii) weight reduction; there is some evidence to suggest decreasing risk of colon and breast cancers.

Glycaemic load (GL) extends the concept of GI considering the GI and the amount of a

carbohydrate have on postprandial blood glucose levels.

GL= (Carbohydrate in food portion (g) x GI)/100

Blood glucose levels rise more rapidly after high GI meal than a low GL meal. It is recommended that a healthy diet should have a low GI and a low GL.

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6.

Vitamins

A vitamin is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. For example, ascorbic acid (vitamin C) is a vitamin for humans, but not for most other animals, and biotin or vitamin D is required in the human diet only in certain circumstances.

Vitamins are classified as either water-soluble or soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-fat-soluble (8 B vitamins and vitamin C). Water-fat-soluble vitamins dissolve easily in water and, in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. Because they are not as readily stored, more consistent intake is important. Many types of water-soluble vitamins are synthesized by bacteria. Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats). Because they are more likely to accumulate in the body, they are more likely to lead to hypervitaminosis than are water-soluble vitamins.

6.1 Fat-soluble vitamins

Vitamin A (retinol) and carotenoids

Vitamin A is the term for the biologically active compound retinol and its provitamin (precursor) carotenoids. The most common provitamin A carotenoids are β-carotene, α-carotene, ɣ-carotene, and β-cryptoxanthin. Only 50 of approximately 600 naturally occurring carotenoids are converted into vitamin A. Carotenoids with no vitamin A activity include zeaxanthin, the pigment in sweet corn, and lycopene, the red pigment in tomatoes. The vitamin A activity of β-carotene is calculated as 6 µg being equivalent to 1 µg of retinol. Other carotenoids are considered to have less activity. Function

 Vitamin A is essential for the production of rhodopsin in the rods of the retina. Exposure to light results in a series of changes in the configuration of rhodopsin, which leads to the adaptation of vision in the dark.

 Growth, cell differentiation. Vitamin A ensures normal epithelial tissue (skin and mucosa) condition. Vitamin A is necessary for cells to grow and multiply. In the absence of vitamin A, the skin and mucous membrane dryness, skin cracks appear the level of resistance to infections.

 Embryogenesis.  Immune response.

29 Recommended dietary allowances: Vitamin A requirement expressed in mg retinol equivalents (1 mg retinol equivalent = 1 mg of retinol or 6 mg β-carotene and other carotenoids 12 mg = 3.33 international units). Adult with food need to get about 800 mg of retinol equivalents (5000 IU). Deficiency: Night-blindness (is a condition making it difficult or impossible to see in relatively low light), Hyperkeratosis (is thickening of the stratum corneum, often associated with a qualitative abnormality of the keratin), and Keratomalacia (an eye disorder that leads to a dry cornea).

A few salient facts about vitamin A by WHO. Vitamin A deficiency (VAD) is the leading cause of preventable blindness in children and increases the risk of disease and death from severe infections. In pregnant women VAD causes night blindness and may increase the risk of maternal mortality. Vitamin A deficiency is a public health problem in more than half of all countries, especially in Africa and South-East Asia, hitting hardest young children and pregnant women in low-income countries. An estimated 250 million preschool children are vitamin A deficient and it is likely that in vitamin A deficient areas a substantial proportion of pregnant women are vitamin A deficient. An estimated 250 000 to 500 000 vitamin A deficient children become blind every year, half of them dying within 12 months of losing their sight.

Hypervitaminosis symptoms of overdose are headache, indigestion, nausea, vomiting, bone and joint pain, liver and spleen. Then start peeling the skin epidermis. In pregnant women vitamin A excess hazard - may cause fetal malformations.

Good food sources of vitamin A. Most vitamin A are in animal products including liver (13000

µg/100g), egg yolk (620 µg/100g), 82.5% butter fat (814 µg/100g), cheese "Emmental” (389 µg/100 g), cream 30% fat (249 µg/100g), 2.5% milk fat (20 µg/100g).

Vitamin A provitamin - carotene in vegetable products: carrots (1656 µg/100g), tomatoes (107 µg/100g), red chili (500 µg/100g), apricots (254 µg/100 g), broccoli (143 µg/100g), cabbage (24 µg/100g), spinach (3.4 µg/100g).

Vitamin E

Eight naturally occurring forms of vitamin E are synthesized in plants: four tocopherols (α, β; ϭ; γ) and four tocotrienols (α, β, ϭ; γ). α -tocopherol has the highest biological activity and is used as the standard against which the activity of other forms is measured.

Function

• Antioxidant. Vitamin E is a powerful antioxidant and protects cell membranes and lipoproteins from damage by free radicals.

• Maintenance of cell membrane integrity.

30 Most of the scientific researchers are carried out to demonstrate the effectiveness of vitamin E, to lowering the age-related disease emergence and progression - ischemic heart disease, cancer and cataract.

Recommended dietary allowances (RDA). Vitamin E requirement in mg tocopherol equivalents (1 mg tocopherol equivalents = 1 mg α-tocopherol). RDA of 3 mg α-tocopherol equivalents infants continued to steadily increase of 7-10 years for children up to 7 mg, for women - 8 mg, but during pregnancy - 10 mg and breast feeding - 12 mg; for men - 10 mg.

Deficiency. Experimental, symptomatic vitamin E deficiency has not been induced in humans. Toxicity. Vitamin E has low toxicity but at very high doses it acts as an antagonist to vitamins A, D. and K. Symptoms of toxicity include headache, nausea, muscle weakness, double vision, and creatinuria.

Good food sources of vitamin E are (RDA 10mg): wheat germ oil (10 mg of vitamin E/1 teaspoon

of wheat germ oil), almonds (10 mg/28g), sunflower oil (10 mg/1 table spoon), sunflower seeds (10 mg/14.2 g), peanuts and peanut butter (10 mg/100g).

Vitamin D (calciferols)

The term vitamin D refers to two molecules, ergocalciferol (D2) and cholecalciferol (D3). Cholecalciferol is the most effective form of vitamin D and is manufactured in the skin by the action of ultraviolet radiation on 7-dehydrocholesterol. Dietary ergocalciferol and cholecaciferol are biologically inactive and are activated to 25-hydroxyvitamin D in the liver.

Function

• 1,25-dihydroxyvitamin D maintains plasma Ca by controlling Ca absorption and excretion. Vitamin D and its metabolites are also involved in bone mineralization.

• Children with vitamin D deficiency (rickets) often have impaired immune function that is corrected by the administration of vitamin D.

• It has recently been postulated that vitamin D may inhibit cell proliferation in some forms of cancer.

Deficiency. Severe deficiency results in rickets in children, which is characterized by reduced calcification of bone epiphyses. It results in skeletal deformities, bone pain, and muscle weakness. In adults deficiency results in osteomalacia, which leads to bone pain, and muscle weakness. People who stay indoors and are fully covered are at risk of deficiency due to lack of ultraviolet radiation from sunlight. Supplements are recommended for housebound elderly and some ethnic groups, e.g. Asian and Muslim women due to low sun exposure. Malabsorption increases the risk of deficiency.

31 Requirement. For adults reference nutrient intake - 5 mg per day. Vitamin D requirement expressed in mg cholecalciferol (cholecalciferol 10 mg = 400 IU of vitamin D). During pregnancy and breast feeding women RDA – 10mg/d. Also, the vitamin D is required in patients with certain kidney and liver diseases, the prevention of rickets.

Toxicity. Overdose with supplements results in hypercalcaemia, which has symptoms of thirst and anorexia and is accompanied by the risk of soft tissue calcification and urinary Ca stones.

Good food sources of vitamin D. Vitamin D is manufactured in the skin by the action of

ultraviolet radiation on 7-dehydrocholesterol, (the main source), only a small part of it comes to food.

Vitamin D2 is found in plant products: sunflower, olive oil. Vitamin D3 is found in animal foods: fish oil, eggs and Atlantic herring (8.3 µg/100g), salmon (12.5 µg/100g), egg yolk (4 µg/100g), milk (15-40 µg/100 g), butter (1.23 µg/100 g), lean pork (0.7 µg/100g), cheese (0.02-0.26 µg/100g). Vitamins D are resistant to oxidation and heating, for example, vitamin D2 does not lose activity 1150C temperature.

Vitamin K

Naturally occurring vitamin K can be classified into two groups. The major form of vitamin K1 (phylloquinine) is synthesized by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. Vitamin K2 has several subtypes, one of which (menaquinones) is involved in bone metabolism and are synthesized by intestinal bacteria.

Function

• Vitamin K is essential for blood coagulation. Vitamin K promotes the synthesis of

γ-carboxyglutamic acid (Gla) in the liver. Gla is an essential part for prothrombin (factor II) and other coagulation factors (VII, IX, and X).

Deficiency. Average diets are usually not lacking in vitamin K, and primary deficiency is rare in healthy adults. Newborn infants are at an increased risk of deficiency. Other populations with an increased prevalence of vitamin K deficiency include those who suffer from liver damage or disease (e.g. alcoholics), cystic fibrosis, or inflammatory bowel diseases, or have recently had abdominal surgeries. Secondary vitamin K deficiency can occur in bulimics, those on stringent diets, and those taking anticoagulants. Symptoms of K1 deficiency include anaemia, bruising, and bleeding of the gums or nose in both sexes, and heavy menstrual bleeding in women. Osteoporosis and coronary heart disease are strongly associated with lower levels of K2 (menaquinone).

32 Requirement. Studies into vitamin K requirements are not entirely satisfactory as it is difficult to induce deficiency solely by dietary manipulation. It is suggested that the requirements are between 0.5 and 1.0 µg per kg/d. The adult needs about 60-80 µg (1 µg/1 kg of body weight per day). The U.S. Dietary Reference Intake (DRI) for an Adequate Intake (AI) of vitamin K for a 25-year old male is 120 µg/day. The Adequate Intake (AI) for adult women is 90 µg/day, for infants is 10-20 µg/day, for children and adolescents’ 15-100 µg/day.

Good food sources of vitamin K.

Vitamin K1 in plant foods: spinach (601 mg/100g), potatoes (452 mg/100g), radishes (350 mg/100g), green peas (338 mg/100g), sorrel (333 mg/100g), cabbage (328 mg/100g), tomatoes (260 mg/100g), salad leaves (255 mg/100g), carrots (251 mg/100g), raisins (684 mg/100g); bananas (370 mg/100g), black currant (306 mg/100g) melons (289 mg/100g).

Small amounts of vitamin K2 are animal products: pork liver, eggs, and dairy products.

6.2 Water-soluble vitamins

Vitamin C (ascorbic acid)

Most animals can synthesize vitamin C from glucose or galactose. However humans, primates, guinea-pigs, Indian fruit-eating bats, and some birds lack this ability and it is an essential nutrient in these species.

Function

Vitamin C is a powerful reducing agent (antioxidant) and is essential for many oxidation-reduction reactions.

• Vitamin C is required for the synthesis of collagen, the main protein in connective tissue essential for the maintenance of muscles, tendons, arteries, bone, and skin. It is essential for the normal functioning of enzymes involved in collagen synthesis.

• The hydroxylation of dopamine to the neurotransmitter noradrenaline requires vitamin C. • Vitamin C is required for the production of carnitine. Low levels of carnitine are associated

with fatigue and muscle weakness.

• Various peptide hormones and releasing factors require activation by a vitamin C dependent enzyme.