Course: B.Sc. BiochemistrySub: introduction to biochemistry

UNIT-3.2

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INTRODUCTIONNutrition may be defined as the science of

food and its relationship to health. It is concerned primarily with the part played by nutrients in body growth, development and maintenance .

The word nutrient or “food factor” is used for specific dietary constituents such as proteins, vitamins and minerals. Dietetics is the practical application of the principles of nutrition; it includes the planning of meals for the well and the sick. Good nutrition means “maintaining a nutritional status that enables us to grow well and enjoy good health.”

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Protein, carbohydrate and fat had been recognized early in the 19th century as energy-yielding foods and much attention was paid to their metabolism and contribution to energy requirements.

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CLASSIFICATION OF FOODS Classification by origin: - Foods of animal origin

- Foods of vegetable origin

Classification by chemical composition: - Proteins

Fats Carbohydrates Vitamins Minerals

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CLASSIFICATION BY PREDOMINANT FUNCTIONBody building foods:-meat, milk, poultry, fish, eggs, pulses etc

Energy giving foods:-cereals, sugars, fats, oils etc.

Protective foods:-vegetables, fruits, milk, etc

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NUTRIENTSOrganic and inorganic complexes

contained in food are called nutrients. They are broadly divided in to:

Macronutrients:-proteins-fats-carbohydrates

Micronutrients:-vitamins-minerals

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PROTEINSPROTEINS ARE COMPLEX ORGANIC

NITROGENOUS COMPOUNDS.THEY ALSO CONTAIN SULFUR AND I SOME

CASES PHOSPHOROUS AND IRON.PROTEINS ARE MADE OF MONOMERS

CALLED AMINO ACIDS.THERE ARE ABOUT 20 DIFFERENT

AMINOACIDS WHICH R FOUND IN HUMAN BODY.

OF THIS 8 AA ARE TERMED “ESSENTIAL” AS THEY ARE NOT SYNTHESIZED IN HUMAN BODY AND MUST BE OBTAINED FROM DIETARY PROTIENS.

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Functions of ProteinsBody buildingRepair and maintenance of body

tissuesMaintenance of osmotic pressureSynthesis of bioactive substances

and other vital molecules

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Evaluation of proteinsThe parameters used for net

protein evaluation are:

Biological valueDigestibility coefficientProtein efficiency ratio Net protein utilization (NPU)

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Assessment of Protein nutrition status Protein nutrition status is measured by Serum

Albumin Concentration.

It should be more than 3.5 g/dl.

Less than 3.5 g/dl shows mild malnutrition.

Less than 3.0 g/dl shows severe malnutrition.

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FATMost of the body fat (99 per cent) in

the adipose tissue is in the form of triglycerides, in normal human subjects, adipose tissue constitutes between 10 and 15 per cent of body weight. One kilogram of adipose tissue corresponds to 7700 kcal of energy.

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Essential fatty acids are those that cannot be synthesized by humans

Dietary sources of EFALinoleic acidSunflower oil Corn oil Soya bean oil Sesame

oil Groundnut oil Mustard oil Palm oil Coconut oil

Arachidonic acidMeat, eggs, milk Linolenic acidSoya bean oil, Leafy greens

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Functions of fatsThey are high energy foods, providing as much

as 9 kcal for every gram. Fats serve as vehicles for fat-soluble vitamins Fats in the body support viscera such as heart,

kidney and intestine; and fat beneath the skin provides insulation against cold.

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The “non-calorie” roles of fat vegetable fats are rich sources of essential fatty

acids which are needed by the body for growth, structural integrity of the cell membrane and decreased platelet adhesiveness.

Diets rich in EFA have been reported to reduce serum cholesterol and low-density lipoproteins.

Polyunsaturated fatty acids are precursors of prostaglandins.

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Fat requirementsIn developed countries dietary fats provide 30 to

40 per cent of total energy intake. The WHO Expert committee on Prevention of Coronary Heart Disease has recommended only 20 to 30 per cent of total dietary energy to be provided by fats. At least 50 per cent of fat intake should consist of vegetable oils rich in essential fatty acids.

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CARBOHYDRATECarbohydrate is the main source

of energy, providing 4 Kcals per one gram Carbohydrate is also essential for the oxidation of fats and for the synthesis of certain non-essential amino acids

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Sources of carbohydratesThere are three main sources of carbohydrate, viz.

starches, sugar and cellulose.The carbohydrate reserve (glycogen) of a human

adult is about 500g. This reserve is rapidly exhausted when a man is fasting. If the dietary carbohydrates do not meet the energy needs of the body, protein and glycerol from dietary and endogenous sources are used by the body to maintain glucose homeostasis.

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Dietary fibreDietary fibre which is mainly non-starch

polysaccharide is a physiological important component of the diet. It is found in vegetables, fruits and grains. It may be divided broadly into cellulose and non-cellulose polysaccharides which include hemi-cellulose pectin, storage polysaccharides like inulin, and the plant gums and mucilage. These are all degraded to a greater of lesser extend by the micro flora in the human colon

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VITAMINSVitamins are a class of organic compounds

categorized as essential nutrients. They are required by the body in a very small amounts. They fall in the category of micronutrients.

Vitamins are divided in to two groups: fat soluble vitamins- A, D, E and K and water soluble vitamins: vitamins of the B-group and vitamin C.

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VITAMIN AVitamin A» covers both a pre-

formed vitamin, retinol, and a pro-vitamin, beta carotene, some of which is converted to retinol in the intestinal mucosa.

The international unit (IU) of vitamin A is equivalent to 0,2 microgram of retinol (or 0,55 microgram of retinal palmitate).

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Functions of Vitamin AIt is indispensable for normal vision. It contributes to the production of retinal

pigments which are needed fro vision lights.It is necessary for maintaining the integrity and

the normal functioning of glandular and epithelial issue which lines intestinal , respiratory and urinary tracts as well as the skin and eyes.

It supports growth, especially skeletal growthIt is antiintencive. It may protect against some epithelial cancers such

as bronchial cancers.22

Deficiency of vitamin A The signs of vitamin A deficiency are

predominantly ocular. They are:

Nightblindness Conjunctival xerosis Bigot's spots Corneal xerosis Keratomalacia

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VITAMIN D

The nutritionally important forms of Vitamin D in man are Calciferol (Vitamin D2) and Cholecalciferol (Vitamin D3).

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Functions of vitamin D and its metabolites

Intestine: Promotes intestinal absorption of calcium and phosphorus

Bone: Stimulates normal mineralization, Enhances bone reabsorption, Affects collagen maturation

Kidney: Increases tubular reabsorption of phosphate

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Deficiency of vitamin DDeficiency of vitamin D leads to:

Rickets

Osteomalacia

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THIAMINEThiamine (vitamin B1) is a water

soluble vitamin. It is essential for the utilization of carbohydrates. Thiamine pyrophosphate (TPP), the coenzyme of cocarboxylase plays a part in activating transkelolase, an enzyme involved in the direct oxidative pathway for glucose.

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Deficiency of thiamine The two principal deficiency diseases are beriberi

and Wernick's encephalopathy. Beriberi may occur in three main forms: peripheral neuritis, cardiac beriberi infantile beriberi, seen in infants between 2 and 4

months of life. The affected baby is usually breast-fed by a thiamine-deficient mother who commonly shows signs of peripheral neuropathy.

Wernick’s encephalopathy is characterized by ophthalmoplegia, polyneuritis, ataxia and mental deterioration

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VITAMIN B6Pyridoxine (vitamin B6) exists in three forms

pyridoxine, piridoxal and pyridoxamine. It plays an important role in the metabolism of amino acids, fats and carbohydrate.

The requirement of adults vary directly with protein intake. Adults may need 2 mg/day, during pregnancy and lactation, 2.5 mg/day. Balanced diets usually contain pyridoxine, therefore deficiency is rare.

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VITAMIN B12Vitamin B12 is a complex organo-metallic

compound with a cobalt atom. The preparation which is therapeutically used is cyanocobalamine.

Vitamin B 12 cooperates with foliate in the synthesis of DNA.

Vitamin B 12 has a separate biochemical role, unrelated to folate, in synthesis of fatty acids in myelin

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Vitamin B12 deficiency Vitamin B12 deficiency is associated with

megaloblastic anaemia (per nicous anaemia), demyelinating neurological lesions in the spinal cord and infertility (in animal species). Dietary deficiency of B12 may arise the subjects who are strict vegetarians and eat no animal product. At the present time there is little evidence that vitamin B12 deficiency anaemia represents an important public health problem.

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VITAMIN CVitamin C (ascorbic acid) is a water-soluble

vitamin. It is the most sensitive of all vitamins to heat. Man, monkey and guinea pig are perhaps the only species known to require vitamin C in their diet

Vitamin C has an important role to play in tissue oxidation it is needed for the formation of collagen, which accounts for 25 per cent of total body protein

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Deficiency of vitamin C Deficiency of vitamin C results in

scurvy, the signs of which are swollen and bleeding gums, subcutaneous bruising or bleeding into the skin or joints, delayed wound healing, anaemia and weakness. Scurvy which was once an important deficiency disease is no longer a disease of world importance.

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NUTRITIONAL PROFILES OF PRINCIPAL FOODS

The principal food includes:

Cereals

Millets

Pulses34

CerealsCereals (e.g. rice, wheat) constitute the bulk of

the daily diet. Rice is the staple food of more than half the human race. Next to rice, wheat is the most important cereal. Maize ranks next to rice and wheat in world consumption. Maize is also used as food for cattle and poultry because it is rich in fat, besides being cheaper than rice or wheat.

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Assessment of protein in cerealsProtein quality:The quality of a protein is assessed by comparison to the “

reference protein” which is usually egg protein . Two methods of assessment of protein quality need be mentioned:

(i) Amino acid score: It is measure of the concentration of each essential amino acid in the reference protein.

Number of mg of one amino acid per g of protein Amino acid score= ……….......................................... x 100 Number of mg of the same amino acid per g of egg

protein.Net protein, utilization (NPU): Nitrogen retained by the body

NPU=.......................................................................x 100 Nitrogen intake In calculating protein quality, 1 gram of protein is

assumed to be equivalent to 6.25 g of N.

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Calculating protein quantity of cereals Protein quantity: The protein content of many Indian foods has

been determined and published in food composition tables. One way of evaluating foods as source of protein is to determine what per cent of their energy value is supplied by their protein content. This is known as Protein – Energy Ratio (PE ratio or percentage).

PE per cent = Energy from protein x 100 Total energy in diet

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Fat requirements from cerealsThe daily requirement of fat is not known

with certainty. During infancy, fats contribute to a little over 50 per cent of the total energy intake. This scales down to about 20 per cent in adulthood. The ICMR Expert Group (1981) has recommended an intake of 20 per cent of the total energy intake as fat , of which at least 50 per cent of fat intake should consist of vegetable oils rich in essential fatty acids. The requirement of essential fatty acids ranges from 3 per cent intake to 6 per cent of energy intake in young children. 38

Carbohydrate requirements from cereals

The recommended intake of carbohydrate in balanced diets is placed so as to contribute between 50 and 70 per cent of total energy intake. Most Indian diets contain amounts more than this providing as much as 90 per cent of total energy intake in some cases,

which makes the diet imbalanced.

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Other recommended intakesfrom cerealsFat soluble vitaminsThe recommended dietary allowance of vitamin

E is placed at 10 mg of alpha tocopherol equivalents for adult males and 8 mg for adult females.

Water soluble vitaminsThe requirements of thiamine , riboflavin and

niacin are closely related to energy intake and utilization, and are started in terms of 1000 kcal intake of energy as below:

Thiamine 0.5 mg/1000kcalRiboflavin 0.6 mg/1000kcalNiacin 6.6 mg/1000kcal

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Healthy diet (Balanced Diet)A healthy diet is one that helps maintain or improve general

health. A healthy diet provides the body with essential nutrition: fluid, adequate essential amino acids from protein, essential fatty acids, vitamins, minerals, and adequate calories. The requirements for a healthy diet can be met from a variety of plant-based and animal-based foods.

A healthy diet supports energy needs and provides for human nutrition without exposure to toxicity or excessive weight gain from consuming excessive amounts. Where lack of calories is not an issue, a properly balanced diet (in addition to exercise) is also thought to be important for lowering health risks, such as obesity, heart disease, type 2 diabetes, hypertension and cancer.

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MALNUTRITION: INTRODUCTION

Malnutrition essentially means “bad nourishment”. It concerns not enough as well as too much food, the wrong types of food, or the inability to use nutrients properly to maintain health.

The World Health Organization cites malnutrition as the greatest single threat to the world's public health.

Malnutrition in all its forms is a considerable public health concern and is associated with increases risk of disease and early death.

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MALNUTRITION: : INTRODUCTION

In 2006, more than 36 million people died of hunger or diseases due to deficiencies in micronutrients; accounted for 58% of the total mortality in the same year.

Under nutrition contributes to almost 35% of the estimated 7.6 million deaths under-5 deaths; consequently affecting the future health and socioeconomic development and productive potential of the society.

The malnourished are unable to live a normal life, are less likely to fulfill their potential as human beings and cannot contribute fully to the development of their own countries.

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MALNUTRITION

The World Health Organization defines malnutrition as "the cellular imbalance between supply of nutrients & energy and the body's demand for them to ensure growth, maintenance, and specific functions”.

Malnutrition comprises both;

1. Under nutrition

2. Over nutrition

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TYPES OF MALNUTRITION

• Under nutrition is depletion of energy (calories) resulting form insufficient food intake over an extended period of time.

• In extreme cases under-nutrition is called Starvation. While Famine is severe food shortage of a whole community.

Specific Deficiency is the pathological state resulting form a deficiency of an individual nutrient such as vitamin A deficiency, iodine deficiency.

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TYPES OF MALNUTRITION

Over nutrition:

Many tend to think malnutrition only in terms of hunger, however, overeating is also a contributing factor.

• “Over nutrition is the pathological state resulting from the consumption of excessive quantity of food over an extended period of time”.

• Overweight and obesity are very common conditions in developed society and are becoming more common in developing societies and those in transition.

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NUTRITIONAL DEFICIENCY DISEASES

On global scale the five principal nutritional deficiency diseases are:

1. Kwashiorkor

2. Marasmus

3. Xerophthalmia

4. Nutritional anemia

5. Endemic goiter

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MALNUTRITION IN CHILDREN: PROTEIN-ENERGY MALNUTRITION

In children, protein–energy malnutrition is defined by “measurements that fall below 2 standard deviations under the normal weight for age (underweight), height for age (stunting) and weight for height (wasting)”.

Protein– energy malnutrition usually manifests early, in children between 6 months and 2 years of age and is associated with early weaning, delayed introduction of complementary foods, a low-protein diet and severe or frequent infections.

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UNDERNUTRITION

ACUTE UNDERNUTRITIO

N

CHRONIC UNDERNUTRITIO

N

• Marasmus• kwashiorkor• Marasmic- kwashiorkor• Wasting

TYPES OF UNDERNUTRITION

• Stunting• Underweight

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PROTEIN-ENERGY MALNUTRITION

MANIFESTATIONS OF UNERNUTRITION

Under nutrition results in the loss of body weight. The loss of weight is a manifestation of energy depletion.

Malnutrition from any cause retards normal growth. Malnourished children grow up with worse health and lower educational achievements.

Decrease in immunity increases the susceptibility to infections such as T.B, which add to the morbidity and mortality.

Malnutrition is also associated with lowered vitality of the people leading to lowered productivity and reduced life expectancy.

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MANIFESTATIONS OF OVERNUTRITION

In the more developed countries of the world, over nutrition is encountered much more frequently than under nutrition.

The health hazards from over nutrition are:

1. Obesity,

2. Diabetes,

3. Hypertension,

4. Cardiovascular diseases,

5. Renal diseases,

6. Disorders of liver and gall bladder.

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GLOBAL BURDEN OF MALNUTRITION

Despite the fact that the world already produces enough food to feed everyone — 6 billion people — and could feed the double — 12 billion people.

There were 925 million undernourished people in the world in 2010, an increase of 80 million since 1990.

Nearly 17% of people in the developing world are undernourished.

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Percentage Population Undernourished World Map

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GLOBAL BURDEN OF MALNUTRITION1 out of 3 people in developing countries are affected by

vitamin and mineral deficiencies and therefore more subject to infection, birth defects and impaired physical and psycho-intellectual development.

Under nutrition, an important part of the complex, affects millions of people, mainly in Africa, Asia and Latin America.

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SCOPE OF THE PROBLEM

Directly or indirectly the concurrent vicious life cycle of malnutrition contributes to almost 35% of the estimated 7.6 million deaths under-5 deaths; consequently affecting the future health and socioeconomic development and productive potential of the society.

South Asia is the worst affected region with half of the world’s malnourished children are to be found in just 3 countries Bangladesh, India and Pakistan.

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GLOBAL BURDEN OF MALNUTRITION

This is one side of picture. 2 out of 3 overweight and obese people now live in developed countries, the vast majority in emerging markets and transition economies.

By 2010, more obese people will live in developing countries than in the developed world.

Under-and over-nutrition problems and diet-related chronic diseases account for more than half of the world's diseases and hundreds of millions of dollars in public expenditure.

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PEOPLE AT RISK

Protein-energy malnutrition (PEM) occurs more commonly in three situations:

1. In young children in poor communities, usually in developing countries.

2. In adults, even in affluent countries, due to severe illness (hospital malnutrition).

3. In people of all ages in a famine.

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PEOPLE AT RISK

Although the under nutrition affects all age groups; however the most vulnerable groups are pregnant women, lactating women and young children, mainly because they have a relatively greater nutritional requirements and are more susceptible to the harmful consequences of deficiencies.

Under nutrition affects all age groups, but it is especially common among the poor and those with inadequate access to health education and to clean water and good sanitation.

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Malnutrition is primarily due to:

1. An inadequate intake of food (food gap) both in quantity and quality.

2. Infections, particularly diarrhea, measles, intestinal worms and respiratory infections.

In fact it is a vicious circle – Infections make malnutrition worse and poor nutrition increases the severity of infectious diseases.

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INFECTION AND MALNUTRITION

Inadequate dietary intake

Weight lossGrowth flatteringDecreased immunityMucosal damage

Appetite lossNutrient lossMalabsorptionAltered metabolism

Disease: increase in incidence, duration, severity

MALNUTRITION CYCLE

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DETERMINANATS OF MALNUTRITION 6

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PREVENTION OF MALNUTRITION

Since malnutrition is the outcome of several factors, it requires a coordinated approach of many disciplines at various levels;

1. Family

2. Community

3. National

4. International

ACTION AT FAMILY LEVEL

The principal target of nutritional improvement in the community is family.

The instrument for combating malnutrition at the family level is “Nutrition Education”.

The community health workers can play an important role in nutrition education to the families in their respective areas.

ACTION AT FAMILY LEVELNutrition education should educated family on :

1. Selection of right kind of local foods.

2. Planning of nutritionally adequate diets within limits of their purchasing power.

3. Identification and correction of harmful food taboos & dietary prejudice.

4. Promotion of breast feeding and adequate infant & child feeding .

5. Consider the nutritional needs of expectant & nursing mothers and children in the family.

6. Planning a kitchen garden or keeping poultry.

ACTION AT COMMUNITY LEVEL

The solutions to malnutrition can be assisted by governments, but in the end communities will often have the leading role in reducing malnutrition and promoting social development.

People's participation is essential. It is necessary to recognize that the poor will be the principal actors in their own development and to foster policies and programs that empower the underprivileged.

Empowerment and participation of women are particularly important, because women have the most important role in food security (and often in food production), in child care and in family health.

ACTION AT NATIONAL LEVELThe burden of improving the nutritional status of the people,

by and large, is the responsibility of the State.

Prevalent malnutrition in a country is clear evidence of poor development.

Several approaches and strategies at the national level, suggested by FAO/WHO are as follow:

1. Rural development2. Increase agricultural production, distribution and storage3. Stabilization of population4. Nutrition related health services

ACTION AT THE INTERNATIONAL LEVEL

Food and nutrition are global problems, and international cooperation can play an important role in reducing the nutrition problems worldwide.

The multilateral World Food Program was established in 1963 as a mean of providing enough safe food to those in need and to come to the aid of victims in acute emergencies caused by floods, earth quick, droughts, wars, etc.

In September 2000, the United Nations Millennium Declaration was endorsed by 190 countries and was translated into eight Millennium Development Goals (MDGs) to be achieved by 2015.

MILLENNIUM DEVELOPMENT GOAL 1

Health Targets Health Indicators

Goal 1: Eradicate extreme poverty and hunger

Target 1: Halve, between 1990 and 2015, the proportion of people who live below poverty line

The proportion of people whose income is less than one dollar a day.

Target 2:Halve, between 1990 and 2015, the proportion of people who suffer from hunger

Prevalence of underweight children under five years of age

Proportion of population below minimum level of dietary energy consumption

CONCLUSIONUnder nutrition and malnutrition are widespread problem of

poverty and deprivation that affects millions of people, perhaps the majority, in developing countries.

The poor, the hungry and the malnourished are unable to live a normal life, are less likely to fulfill their potential as human beings and cannot contribute fully to the development of their own countries.

Political actions, more than political will, to implement well conceived policies and programs at the national level, while simultaneously acting internationally, can serve to greatly reduce nutrition problems worldwide.

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MkySs5iUbH5Bb_XSuWvuyqtTgZ1vYIi2Cue5O187OLhOtCI5yFJWyOPdm8zqgkKpuI=s1104. https://lh6.ggpht.com/5Gr-nyJeWp0SjL7DSL-fmkj7RIS_sCqOE-

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Books/ Web resources Fundamentals of biochemistry by JL Jain and Jain www.who.int/maternal_child_adolescent/topics/child/malnutrition/en http://en.wikipedia.org/wiki/Healthy_diet www.nhs.uk/Conditions/vitamins-minerals/Pages/vitamins-minerals.aspx