NUTRITIVE VALUE OF VEGETARIAN DIETS
Dr. D. SUBRAMANIAM
(Director Central Food Technological Research Institute Mysore)

It would be difficult for evening all extensive monograph to do justice to a proper classification and assessment of the nutritive values of vegetarian diets as consumed in different parts of the World. In the present paper, an attempt will be made to deal with only certain aspects of the subject with particular reference to vegetarian diets as consumed in India.

There have been several definitions of what constitutes a vegetarian diet. There are some who would like to confine the definition to only such articles of food as are exclusively of plant origin. There are many who would like to include milk and eggs in the group. There are some others who would extend the group to include fish. If we approach the subject from purely ethical considerations, a vegetarian diet should exclude only those forms of food which are obtained through causing visible injury and even death to other forms of life. Even here, the definition of injury and death should be confined to those higher forms of life which have vital organs and circulatory systems similar to man and whose suffering can be visibly seen. Strictly speaking, no life in the world is possible without making use of materials elaborated by other forms of life. When we pluck the leaves or fruits or even seeds from a plant, we are causing a certain amount of injury. The plant does suffer, but the effects are not visible to the eye. Similarly when we take curds and buttermilk, we consume millions of bacteria and other forms of-life, but there again, we do not notice anything with the naked eye. On the other hand, when we slaughter a cow, a pig, a sheep. or a, chicken, we can visibly see the nature of the cruelty inflicted on the animal however merciful the method of killing may be. Human feelings are prompted by reactions which they would themselves experience if placed under similar conditions. We do not like to see a fellow-being injured, let alone slaughtered. With this as the background we will consider the nature and nutritive values of foods which are either of plant origin or derived from animals without causing any visible suffering or loss of life. This classification will naturally include milk and eggs, but exclude fish.

Almost everywhere in the world there are two classes of vegetarians: (1) those who consume such foods on the basis of religious and sentimental considerations, and (2) those who eat a predominantly vegetarian diet as the result of environmental conditions or necessity - the latter chiefly on account of economic considerations. Thus, over many parts of India, we find people who are classed as non-vegetarians, but who can not afford to get even small amounts of milk, let alone meat, fish, or eggs. From considerations of nutrition, we have taken into account all people who eat a predominantly vegetarian diet, whether by conviction or by necessity.

Over a large part of the World, the dietary patterns of people are determined by food materials which are abundantly available in the respective regions. This is particularly so in the case of vegetarian diets, Thus, we find large sections of vegetarians whose diets are predominantly based on rice, wheat, millets or root crops as the case may be. There are other parts of the World where banana or bread-fruit forms the major article of food. All such bulky articles of food are mainly sources of starch and are important energy producers. In the majority of vegetarian diets, starch forms the major part of the food. In many of the European countries as also in America, starch (generally in the form of bread) form hardly 10 to 15% of the diet. An extreme type of this would be the diet of the Esquimos, which is made up predominantly of animal fat and proteins and contains practically no starch, The slightly varied types of diet would show that the human system is adaptable and can gradually, if not immediately, adjust itself to any type of diet.

Starch, whether in the free condition or as associated with other food ingredients, is mostly converted into sugar and burnt in the human body. Part of it is also converted into fat. Starch by itself cannot, however build up bones and tissues which are largely made up of minerals and proteins respectively; the latter have to come from some other sources.

The major part of the protein in vegetarian diets comes from cereals. A fair part also comes from pulses, nuts, and also from milk and eggs. The proteins from different sources supplement each other and the quality is generally made up. According to International standards one should consume as much as 70 gms. of protein per day, but there is growing evidence to show, especially in the Tropics, that people can maintain normal health even on smaller amounts of proteins. There is however, a substantial amount of evidence to show that general well-being and resistance to disease are associated with a generous intake and utilization of proteins. Proteins should also be well balanced in respect of essential amino-acids. If in addition to the cereal, the daily diet also includes 5 to 10% of a good pulse, at least 10 ozs. of milk and about two eggs it will then generally provide a fair blend of the essential aminoacids. There are, of course, certain related factors and they have some bearing on the protein value of the diet.

The proteins present in cereals and millets, as also pulses, are associated with varying amounts of other components. Rice by itself does not contain much fibre especially when it is polished. On the other hand, millets and pulses include fair amounts of other substances which are not easily assimilated. They also interfere, to varying extents, with the utilization of the associated proteins and minerals. The extent of such interference varies with the individual and is also determined by other factors like age, occupation, etc. Speaking generally, many vegetarian diets lead to bulky residues which are mostly voided. Certain components-chiefly derived from vegetables, are liable to fermentation, but that can be controlled if not completely eliminated.

A fair part of the diet of vegetarians - at any rate in South India - is made up of vegetable dishes which are consumed in the forms of curries, soups, and other preparations. There are dozens, if not hundreds, of such vegetables and they have come into usage largely as the result of long experience. Some of the vegetables especially when they are soft and tender, are easily assimilated. Besides being tasty they also provide minerals, vitamins, and a certain amount of necessary roughage. On the other hand, there are also coarse and mature vegetables which are often cheap and therefore consumed in large quantities. A scientific classification of these has just been started. The evidence already collected would show that there is a considerable amount of truth in the earlier classification in relation to properties - some of them being easy to digest and hence wholesome, some which are coarse and slow to digest, and some which are only partly digested and yield fermentable residues. Vegetables do affect the numbers and activities of intestinal flora. Those which are slow to digest lead to abnormal increase in the anaerobic and gas-forming bacteria in the cecum.

An important factor affecting the quality and the rate of utilization of a vegetarian diet is the nature and quantity of fat present in it. Generally speaking, fat in one form or another, improves the taste of the food and hence is liked by all classes of consumers. Fat is also a highly concentrated form of energy-giving food. At the same time, fat beyond a level of 5 or 10% - whether in the form of ghee, vanaspati, or oil - tends to retard growth unless the food is also adequately supplemented with good proteins. As many of the poor vegetarian diets are somewhat deficient in protein, there is a prima facie case for reducing the amount of fat in the usual vegetarian diet. A large section of consumers has found this by experience, though quite a large number are still unaware of it. There is, of course, a certain amount of individual variation in response to fat. The condition of health is also an important factor. Speaking generally, boiled foods are generally better digested and utilized than fried foods. In the latter case, the fat itself undergoes a change on prolonged heating and forms harmful ingredients that affect health. Fried food components are not also easily digested by the body juices.

Vegetarian diets, especially in the tropics, are associated with the use of certain food adjuncts and spices. It will be quite correct to say that such diets would be monotonous and unappetizing without the addition of these adjuncts. Tamarind and chilli form important food adjuncts over a large part of South India. A liberal use of pickles will also come in the same category. These definitely help to increase the food intake in human subjects. It would be correct to say that the food intake will go down by 50% or more if these food adjuncts are not included in the diet. They do not, however, contribute directly to nutrition. They do, however, indirectly contribute to growth, because of the effects of larger intake. Their mode of action has not yet been clearly understood. According to the Indian system of medicines, these food adjuncts are considered to be harmful in the long run. Although some scientific work has already been done on the subject, more information is needed before definite conclusions can be drawn.

Spices and aromatics form important adjuncts to all types of dietary and particularly to vegetarian diets. Most of them are included in small quantities, and at these levels they are essentially flavouring substances. They do not play any direct part in nutrition but they serve indirectly as appetizers by facilitating a greater intake of food. At high concentrations, some of the aromatics check the growth of putrefactive and pathogenic organisms. This effect is seen in the preservation of certain categories of pickles and sweets. The same effect is also seen in the intestinal tract when they are taken in medicinal doses. Among these, special mention may be made of garlic and asafoetida, both of which act in the same way as some of the orally administerable antibiotics. Most of the putrefactive and fermentative changes occurring in the digestive tract are controlled by a liberal use of garlic, the potency being generally proportional to the pungency of the product. A paste of raw garlic may have an objectionable smell to a large section of people but the beneficial effects are quite striking. Other aromatics have also similar effects, but some of them may prove to be irritating and should be used with care. All aromatics should be used in moderation, because it is generally known that several of the organisms develop resistance to them - as also to antibiotics-on continued usage.

Salt has a very important place in the dietary of vegetarians. Most of the vegetarian diets, as consumed, especially in South India, are somewhat acidic. They are not relished by the consumers unless an adequate amount of salt is added to the diet. The average consumption of salt in South India is of the order of 20 to 26 gms per day, though many users are known to consume as much as 35 gms or even 60 gms per day. The effect of the continued heavy intake of salt would require thorough study. The partially purified sea salt, as consumed over a large part of India, is associated with certain mineral impurities and particularly calcium which are useful. One of the major defects of the average vegetarian diets, especially when they do not include enough milk, is inadequacy of calcium. The usual bazaar salt consumed with our diet contributes 16 to 20% of the daily requirement of calcium. Similarly Pan which is consumed by a large section of our people also contributes some calcium because of the lime taken with it.

Vegetarian diets, if sufficiently varied, are not deficient in most of the vitamins. In the poorer diets, many of the vitamins and particularly A, B-1, D and B-12 are known to be deficient. If these deficiencies are not properly corrected in early stages, much larger quantities are required as therapeutic doses at a later stage.

Generally speaking, good vegetarian diets, if properly planned, should provide all the requirements of human nutrition. At the same time, it should be recognized that quite a large section of people cannot afford a rich and varied vegetarian diet. They have to subsist mainly on grains or roots and their diets show multiple deficiencies. Considering their needs, there is a very strong case for supplementing their diets with cheap and concentrated supplements that will provide adequate amounts of proteins, minerals, and vitamins. Some of the best sources of proteins are the oil-seed meals which are now used either as animal feeds or as manures. The commercial products are unsuitable for human consumption because of the dirt and fibre associated with them. By careful selection and handling of the kernels, very clean attractive meals can be obtained. By further processing. the meals can be made into high class food supplements. The Multi-purpose Food is one such product and even one or two ounces of it will correct the deficiency in the diets of most sections of people. Such supplements are particularly needed by growing children as also by expectant and nursing mothers.

Some special consideration should be given to vegetarian diets which are predominantly based on root crops. Under the present conditions prevalent in some of the densely peopled countries of the world, the use of root crops has become a steadily growing necessity. Root crops like tapioca or sweet potato, are very heavy yielders, capable of giving several tons of starchy food per acre. It would be at least 3 to 4 times as much as one can expect in the form of foodgrains. These starchy foods have, however, one major defect. They are highly deficient in proteins. Tapioca, for instance, contains hardly 0.5% protein. If one is to get 70 gms. of protein per day, one must eat about 35lb. of the root which is physically impossible. It will naturally follow that such diets consumed in the normal may will lead to protein deficiency and various attendant disorders. Evidence has been adduced to show that tapioca can replace about 25% of the rice or other cereal or millet in the vegetarian diet for a short period, but it would not be desirable to continue on such a diet indefinitely. If there is no adequate control, there is always the risk of the consumers - especially of the low income groups - over-eating such products. In the case of such crops, it is absolutely necessary in the long range interests of the consumers, to fortify them with adequate amounts of proteins before distribution to people. One of the elegant methods of such fortification would be to incorporate the protein-rich oil-seed meals along with tapioca or sweet potato flour. A still more elegant and efficient method will be to to make composite foods using such blends which can be consumed in the same may as foodgrains. This type of work is now being done, for the first time at the Central Food Techological Research Institute, Mysore, and the products are being tried out on a large scale in the State of Kernla. The advantage of such an approach would be that we can produce much more food of good quality per acre, than would be possible in the form of food-grains. There is already a fair amount of evidence to show that food-grain production cannot be stepped up indefinilely in keeping with the needs of the rapidly growing population. By taking advantage of abundantly yielding crops and by application of scientific processing, the problem of food shortage came be adequately dealt with on a long range basis.

A major problem of the predominantly vegetarian countries of tlie world, especially in East and South-East Asia, is the rapid increase in population with the attendant consequences of various types. Enforced vegetarianism is itself the result of the growing pressure of population on land. It has often been argued that the vegetarian diet and particularly the rice diet is responsible for the greater birth-rate, among such people. It has also been reported that rice contains a principle which leads to increased fertility of the human race. This is not, however, substantiated by any scientific evidence. There is, in fact, nothing to show that a vegetarian, and particularly the rice-eater, is necessarily more prolific than a non-vegetarian. The non-vegetarian can be equally if not more prolific, and experience of European countries especially during and after the Wars, will show that their population can also increase at a very rapid rate, The present check in population in those countries are due to other factors among which scientific family-planning plays a very big part. Even in India, the large increase in population in recent years has been in States where rice is not the chief article of diet. In any case, a vegetarian diet, particularly a rice diet, cannot be incriminated as being exclusively responsible for the abnormal increase in the population in the South.East Asian countries. The problem is of course there and has to be tackled by the same effective methods as have worked successfully in many of the Western countries.