DEFINITIONA function of living plants and animals,

consisting in the taking in and metabolism of food material whereby tissue is built up and energy liberated.

The study of the food and liquid requirements of human beings or animals for normal physiologic function, including energy, need, maintenance, growth, activity, reproduction, and lactation.

INTRODUCTION

The food we eat determines the way we look, and to some extent the way we feel, think, and behave.

Composition of food and the importance of different articles. Also vegetable sources (food stuffs available in India)

Too much… or too little of each of the dietary components… what happens.

Special dietary advise to prevent certain diseases.

COMPOSITION OF FOODFood is composed of the same chemicals that

make up our bodies (water, salts, proteins, and so on).

When we talk about diet, foods are classified according to the kinds of nutrients they provide.

These nutrients (substances which are necessary for the body’s growth and functioning) are proteins, carbohydrates, fats, minerals, and vitamins.

PROTEINSThese are the basic substances of our bodies –

the stuff out of which each cell is built.Proteins also provide energy.

SOURCES

Milk

Dried peas

Pulses

Nuts Soya beans

Deficiency of protein is specially harmful in childhood.

It can lead to impairment of physical and mental growth.

Children with deficiency are more likely to get frequent infections.

In adults, though growth is complete, protein deficiency leads to weakness, inability to do hard work, frequent infections, and delayed wound healing.

FATS Fats are very concentrated sources of energy.They give twice as much energy as either

proteins or carbohydrates.Those fats which exist in Nature in the solid

state are called fats.Those which are liquid by nature are called oils.

SOURCES

(vegetable sources) include various edible oils (groundnut, gingerly, rape seed, coconut oil). Ghee (animal source).

Some vegetable oils are hydrogenated.They are treated with particular temperature and

pressure in the presence of a chemical.After this process they can be kept even in hot

climates. In India, a popular example is ‘vanaspathi’

(dalda).During the process, the vegetable oils lose

certain essential components which promote growth and keep the skin healthy.

CARBOHYDRATES Carbohydrates are more commonly known as

starches and sugars. They provide heat and energy. Digestive juices convert these foods into glucose,

which is the form of sugar found in the blood. Glucose is the fuel for the activity of all the cells. Carbohydrates also provide bulk or fiber or

roughage. This is in the form of cellulose, which is the fibrous

material present in many fruit and vegetables.

SOURCES: cereals, starchy vegetables such as potatoes

VITAMINS Vitamins are complex chemical substances

required by the body in very small amounts.There are about a dozen vitamins which are

essential to good health.Vitamins are not produced in the body.However, a well balanced diet supplies all the

vitamins, their actions, symptoms of deficiency, and sources have been given below.

Some Vitamins in Relation to Man

Vitamins Symptoms of deficiency

Action in body Good sources

A Night blindness Normal vision

Normal growth

Carrots, mango, papaya

B1 •Weakness•Altered nerve function

Normal nerve function

Whole cereals sprouts

B2 Pellagra (dermatitis, diarrhea, dementia)

Normal metabolism of proteins, fats & carbohydrates

Whole cereals sprouts

Vitamins Symptoms of deficiency

Action in body Good sources

B3 •Skin disease•Altered nerve function

Normal growth Whole cereals sprouts

Folic acid

Anemia Normal production of red cells

Green leafy vegetables

Vitamins Symptoms of deficiency

Action in body Good sources

Ascorbic acid /C

Scurvy – fatigue, hemorrhage, abnormalities of bones

Wound healing increased resistance to infection

Fresh fruit (oranges, lemons, ‘amala’ gooseberry)

D Rickets – defective bones and muscles

•Normal growth of bones and teeth.•Normal muscle tone

Milk and milk products

MINERALS Minerals required by the body include calcium,

iron, and iodine (though iodine is usually described as a ‘trace element’.

Calcium Is necessary for the maintenance of the teeth

and bones, for clotting of blood, and for muscular contraction.

Sources: milk and mild products, dried fruit (specially dates), fresh fruit (‘sitaphal’ or custard apple), and certain cereals, such as ragi.

Iron Is a component of hemoglobin (the red coloring

substance in the blood), and of myoglobin (the red coloring substance in the muscles).

It is concerned with oxygen transport and cellular respiration.

Deficiency of iron affects the formation of Hb, which is present in lower than normal amounts. This is called anemia.

Sources: dried fruit, nuts, jaggery, dried peas and beans, and green leafy vegetables.

Iodine Is important as it is used by the thyroid gland to

synthesize the hormones, thyroxine and triiodothyronine.

These two hormones influence the body growth and metabolism.

Deficiency of iodine leads to low levels of thyroid hormone in the blood.

Hence the feedback or check on the anterior pituitary and hypothalamus is removed.

Hence the hypothalamus releases the releasing hormone (RH), which brings about release of the stimulating hormones (SH) of the anterior pituitary.

The SH stimulate the thyroid gland, which increases in size – this is called goiter.

Though enlarged, it is unable to produce the hormones, till iodine is provided.

Sources: sea salt, sea food, cereals, and nowadays ‘iodized salt’

HEALTHFUL FOODS

UNHEALTHFUL FOODS

Fast foodCanned

food Saturated fat

DIETS TO REDUCE THE RISK OF DEVELOPING CERTAIN DISEASESCORONARY HEART DISEASE Is a leading cause of death in many countries. In this condition, the arteries which supply

blood to the heart muscle are abnormally narrow.

As a result the blood supply to the heart muscle is less than normal.

Severe cases lead to a ‘heart attack’, and may be fatal.

Many factors have been implicated (smoking, a sedentary lifestyle, stress).

Among these, diet is probably the functional factor.

The arteries accumulate a layer of fatty substance along their inner lining.

The blood vessel thus becomes more and more narrow.

Dietary advice is an important part in both preventing and managing coronary heart disease.

It is very important to note that one of the most important points is to avoid saturated fats.

Saturated fats are present in butter, full cream mild, coconut oil, and margarine.

Eating cholesterol rich foods such as eggs, does not raise blood cholesterol levels as much as eating foods rich in saturated fats.

Another important point – dietary fiber decreases plasma cholesterol.

This depends on the type of dietary fiber.

For eg. Wheat fiber does not reduce blood cholesterol.

Viscous or ‘soluble’ types i.e., pectin and guar do.

Even 5 g/day reduce cholesterol level by 5%.Good sources of soluble fiber are vegetables,

fruit, oatmeal, oat bran, and legumes.Fish is now known to contain protective oils.These substances prevent clots forming in

blood vessels.

HYPERTENSION

SALTA survey conducted in different countries

shows that the prevalence of hypertension correlates with the salt intake.

The WHO Expert Committee on Prevention of Coronary Heart Disease recommended that people not eat more than 6 g of salt a day.

High BP levels can usually be lowered by reducing the salt in the diet.

Components in the diet that may lower BPPOTASSIUM – it was observed that in patients

with mild to moderate hypertension, after increasing their potassium intake.

BP fell by 74 mmHg.This effect is because potassium acts as an

antagonist to sodium at the level of the kidney.Hence more sodium excreted.Sources: potatoes, pulses, fresh fruit (oranges,

bananas), and dried fruits (dates.

MAGNESIUM – in some patients it was observed that magnesium lowered the BP.

These patients were actually known to have lower magnesium levels than normal.

This was due to the fact that most of them were receiving medicines which increased the excretion of sodium, potassium, and magnesium.

Hence making up this magnesium deficiency was believed to beneficial in hypertension.

Sources: bran, whole cereals, and legumes are there riches sources.

FISH OILS – Omega-3 fatty acids present in fish body oil was found to cause a significant fall in BP.

The ‘dose’ of omega-3 fatty acids needed, was higher than could be obtained by eating the ‘usual’ amounts of fish.

CALCIUM – Intake of calcium were more likely to suffer from hypertension, than those who consume normal amounts of calcium.

Other trials noted small and late reduction in BP with 1.0 to 1.5 g.day of calcium.

DENTAL CARIESDental enamel is the hardest material in the

body. It consists chiefly of calcium phosphate, and is

dissolved by acid.Two factors could contribute to caries: Sugars – some diets contain a lot of sugar

enzyme. Infection – Bacteria convert sugars to lactic

acid and also to a layer which covers up or shields the bacteria.

Some people have more bacteria than others.

DiabetesDiabetes (specially non-insulin dependent –

type II) was described as early as 400 BC in India, as a disease of the well fed.

It is closely linked to obesity.People with a high ratio of waist to hip

circumference, are at greater risk.The popular belief that eating a lot of sugar

predisposes to diabetes, is not supported by recent studies.

On the other hand, high fat intake is more likely to lead to diabetes.

About the prevention of Type II diabetes, it was note that a high total carbohydrate (chiefly starch) and high fiber intake are characteristic of present communities in whom type II diabetes is uncommon.

In managing an established case of type II diabetes, the following is recommended.

1. 55% of calories as carbohydrates (preferably unrefined – avoid white flour, polished rice).

2. 35% of calories as fats – avoid butter, cream and other saturated fats.

3. No sorbitrate, fructose instead saccharin – noncaloric sweetener.

4. Less salt.

SOME TYPES OF CANCER

Esophageal cancer is related to alcohol and tobacco.

Stomach cancer has been correlated with smoked/salted fish, preserved meats, and pickled foods.

The cancers most clearly related to certain dietary factors are esophageal, gastric, and large intestine.

Large intestine cancer has been correlated with total fat and protein intake. High protein, low fiber diets have been specially implicated. It is believed that when protein rich foods are cooked at high temperature, substances which produce cancer (carcinogens) are formed. Wheat fiber and bassicae vegetables (cabbages, brussel spouts, and turnips) were found to have protective. Red meat is specially harmful.