Introduction1

The first unit gives the overview of different terminologies in nutrition that will be used throughout this book. This unit also covers the history, macronutrients and micronutrients discovery. There are some common myths which are prevalent among different societies and communities, and their facts will be clarified in this chapter. Numerous superstitious beliefs, cultural taboos and food fads are also highlighted here. Reference terms, dietary recommendations, food group system would throw some light from the readers point of view. Common nutritional problems faced by people living in a country like India needs to be given awareness as to what to be eaten and how to combat those problems in near future. This particular book with its significantly rich chapters would thereby equip a nurse.

The science of nutrition is relatively a youngster in the scientific community and is recognized as a distinct discipline only in 1934. It emerged only after the development of the other branch of science like chemistry, biology, etc.

The history of nutrition is divided into four eras:

Since 1955, there have been many technological developments. After 1960's research in nutrition changed from a search for essential dietary components to a study of the interrelationship among nutrients, their precise role, the determination of human dietary requirements and the effect of processing on the nutrient quality of foods.

History of Vitamins

Vitamins and their discovery are presented in the above table 1.

Takaki: Surgeon in Japanese navy demonstrated that addition of meat and whole grains to diet resulted in disappearance of beriberi.

Eijkman: Dutch physician reported neurological abnormalities in birds fed on highly polished rice diet.

Grijns: Physician suggested the importance of a dietary constituent in preventing deficiency.

Thiamine occurs in the aleuronic layer of food grains and is removed during milling and polishing. Isolated first in 1926.

Riboflavin which has also been known as vitamin B₁, vitamin G and the yellow enzyme was recognized as a vitamin in 1917. At that time, it became clear that vitamin B retained some growth promoting properties even after its anti beriberi properties (B₁) had been destroyed by heat to differentiate the heat labile component of vitamin B₁ and vitamin B₂, respectively. Vitamin B₂ is known to be essential for growth and tissue repair in all animals, from microbes to humans. Riboflavin derives its name from yellow color.

Pyridoxine or vitamin B₆ is unique among the B complex vitamins, in that it functions primarily in protein metabolism. A deficiency of vitamin was first identified in 1951 among infants of middle class families who developed neuromotor seizures as the result of the use of an over processed infant formula. Pyridoxine was first identified in 1934 as a substance capable of curing a characteristic dermatitis in rats that did not respond to any of the 3 factors then known in B complex. It was isolated in 1938 and the structure was identified in 1939.

Vitamin B₁ was discovered simultaneously in UK and USA. It is the only vitamin that has the element cobalt in its structure. In 1926, Minot and Murphy determined pernicious anemia to be a fatal disease, until B₁₂ was discovered and was cured with feeding large amounts of raw liver. Also in 1926 castle noted that patients with pernicious anemia had a low gastric secretion. He postulated that anti-pernicious substances (i.e. vitamin B₁₂) were formed by combination of an Extrinsic factor present in food and an Intrinsic factor in the normal gastric secretion. The search for the extrinsic factor led to the discovery of vitamin B₁₂ now identified as ‘Castle's extrinsic factor’.

Through many years, early in twentieth century, sunlight or body's exposure to ultraviolet light has been contemporarily used in the treatment of rickets. Later on, in 1918, Sir Edward Mellanby showed some evidence of a fat-soluble substance which has the property to prevent the so-called rickets. Mellanby and his co-workers found that the fat-soluble factor D in the diet or body exposure to ultraviolet light is responsible for the prevention and cure of rickets. Vitamin D rich cod liver oil was found to have some active principle, similarly, body exposure to sunlight, initiates the conversion of sterol into vitamin D, which gets activated in liver and kidneys.

Vitamin E was first recognized in 1922 by Evans and Bishop as a dietary factor obtained from plant-based foods that were essential for normal reproduction in rats. In 1933, it was identified as essential for humans and found to comprise a range of substances known as tocopherols and tocotrienols.

Vitamin K was first discovered in 1934 by a Danish scientist named Dam. He found that bleeding in chickens can be prevented by giving lucerne/alfalfa and decayed fish meal. The active principle in these materials were extracted and thus a new fat-soluble vitamin was discovered. Dam named it vitamin K (coagulation vitamin) and isolated it in 1939 along with Swiss chemist Karrer and his colleagues.

Nutrition may be defined as the science of food that deals with its relationship to health with the help of the nutrients such as carbohydrates, proteins, fats, vitamins and minerals to maintain body's growth, repair and maintenance.

Good nutrition is a basic component of health. The relation of nutrition to health may be seen from the following view points.

Nutrients or food factor: Chemical substances in food which perform the function of the body are called nutrients. The various nutrients are carbohydrates, proteins, fats, minerals, vitamins and fiber.

Nutrient requirement: It can be defined as the minimum amount of the absorbed nutrient that is necessary for maintaining the normal physiological functions of the body.

Recommended dietary allowances (RDA): It is defined as the nutrients present in the diet which satisfies the daily requirement of nearly all individuals in a population. These imply addition of safety factor amount to the estimated requirement to cover the variation among the individuals, losses during cooking and the lack of precision inherent in the estimated requirement.

RDA = requirements + safety factor.

Nutritional status: It is the condition of health of the individual as influenced by the utilization of nutrients. It can be determined only by the correlation of information obtained through a careful medical and dietary history, a thorough physical examination and appropriate laboratory investigation.

According to WHO, health is a state of complete physical, mental, social well-being and not merely the absence of any disease or infirmity.

Malnutrition is an impairment of health resulting from a deficiency, excess or imbalance of nutrients. It includes:

Balanced diet: It is one which contains different types of foods in such quantities and proportions so that the need for calories, proteins, minerals, vitamins and other nutrients is adequately met and a small provision is made for extra nutrients to withstand short duration of leanness.

The five food group plan permits an individual to plan a menu to achieve nutrient intakes as specified by RDA. It i s presented in the table below:

The five food group system is applicable for:

The food guide pyramid introduced by USDA (United States Department of Agriculture) in 1992, is used a tool in planning a balanced diet. It is based on five food group concept. It is given in Figure 1.1

Foods may be broadly classified into 11 groups based on their nutritive value: (1) Cereals and millets, (2) Pulses (legumes), (3) Nuts and oilseeds, (4) Vegetables, (5) Fruits, (6) Milk 8and milk products, (7) Eggs, (8) Meat, fish and poultry, (9) Fats and oils, (10) Sugar and other carbohydrate foods and (11) Spices and condiments.

The different groups of foods listed above may be broadly classified under three heads from the nutritional point of view.

Nutritional classification of foods is explained in the above flowchart 1.1

A good diet must fulfill these criteria. It must furnish the appropriate amount of all nutrients meet the physiologic and biochemical needs of body at all stages of the lifecycle.

Growth comprises of increase in size of the body as well as development and maturation of organs and systems of the body. During the growth spurt, a child needs more food in relation to body size than it does as an adult.

There is a relationship of two types between nutrition and infection.

Aged between 29–39 years, weighing 60 kg, sleeping 8 hours, working for 8 hours a day on moderate activity, 4–6 hours on light activity and 2 hours of walking or other household activities.

Aged between 29–39 years, weighing 50 kg, sleeping 8 hours, working 8 hours a day on moderate activity, 4–6 hours on light activity and 2 hours of walking or other household activities.

Personal likes and dislikes in the selection of foods are called as food fads. It may stand in the way of correcting nutritional deficiencies.

Food fads that exist are as follows:

These beliefs have no scientific basis.

There are some food myths that are prevalent among certain communities, myths could be due to ignorance or lack of knowledge about nutrition. In the present scenario, knowledge/awareness about nutrition is wide spreading so people are becoming more conscious about diet than before. Common myths and facts are listed below in the Table 1.3.

Food habits have deep psychological roots and are also considered as the oldest of any culture.

Factors influencing food habits and selection of food includes:

Food habits are handed over from generation to generation in the society particularly in the developing countries.

Thus, the health of the female is affected as they eat poorly with the left over food.

Nutrition and immunity are always interrelated. Nutrients such as proteins, lipids, zinc, vitamin C, vitamin A, iron, copper have been proved to act on defense mechanisms of immune system. Malnutrition leads to infection and infection to malnutrition as a vicious cycle. Malnutrition and health can be described with an example.

Many nutrients are documented to have a protective role in fighting/preventing certain types of cancers. More recent reports suggest that diet perhaps plays an important role in certain types of gastrointestinal cancers, e.g. dietary fiber has been proved to protect against colon cancer, antioxidants such as vitamins E, A, C, selenium proved to be linked with all types of cancers. A colorful rainbow diet with lot of antioxidant rich fruits can help to prevent cancers.

National Health Policy was initiated by the Ministry of Health and Family Welfare, Government of India in 1982. Main motto is to attain the goal of health for all by 2000 AD. Some of the integrated approaches apart from providing good health is to have population control, achieve fuller employment, elementary education, welfare/nutrition programs for women and children, etc.

It was constituted by department of women and child development, Government of India and was approved by the cabinet in April, 1983. It was discussed and approved by both the houses of the parliament in August, 1993. It focuses on ‘comprehensive, integrated, intersectoral strategy for alleviating the multifaceted problem of malnutrition and achieving the optimal nutrition for the people.¹

Malnutrition is a man made disease, the ecological factors related to malnutrition are—poverty, cultural influences, food production, availability and sanitation. Malnutrition predisposes to infection and infection to malnutrition. Direct and indirect effects are seen because of malnutrition. Direct effects lead to nutritional deficiency diseases like kwashiorkor, marasmus, anemia, vitamin A deficiency. High incidence of mortality and morbidity is the indirect form of malnutrition (nearly 50% of total deaths in the developing countries occur among children under 5 years of age compared to less growth and developed countries).

Over nutrition, which is another form of malnutrition is responsible for obesity, diabetes, hypertension, cardiovascular and renal diseases, disorders of liver and gallbladder.

This is the most reported nutritional problem in India. Infants, adolescent girls, pregnant women, elderly people face this common problem. Various strategies such as mandatory iron supplements to children, pregnant women, food fortification programs are all in existence now to reduce the incidence/prevention/treatment of anemias.

There are a specific group of foods which has some components present in them that helps in reducing or minimizing the risk of certain disease conditions and these foods are termed as functional foods. Examples include whole grains, fruits, vegetables, etc. on knowing their health benefits, one can make wise choice of all these food stuffs and get benefitted.

Functional foods are defined as foods that provide more than simple nutrition. They supply additional physiologic benefit for the consumer. They contain a bioactive principle which is responsible for the physiologic benefit. Tables 1.4 and 1.5 depicts the bioactive component present in food item.

The history of nutrition gives us a bird's eye view of the nutritional deficiencies; problems encountered which can be corrected by proper nutritional intervention strategies.