Nutrition and Health, 1992, Vol. 8, pp. 1-16 0260-1061/92 $10 © 1992 A B Academic Publishers. Printed in Great Britain
FOOD AND HEALTH-McCARRISON'S PRESCRIPTION ENDURES* C. GOPALANt The Nutrition Foundation of India
It is indeed an honour and privilege for me to have this opportunity to pay my homage and tribute to Sir Robert McCarrison, a great and distinguished scientist. McCarrison, undoubtedly, laid the foundation for nutrition research in India. The Deficiency Diseases Enquiry (of the Indian Research Fund Association) which he founded and headed with rare devotion and dedication for nearly two decades in the earlier half of this century, was, by current standards, a small unit with limited staff and equipment. However, the string of publications in successive volumes of the Indian Journal of Medical Research for over a decade starting from 1919 bear ample testimony to the quality, range and output ofMcCarrison's pioneering work during this period. That work had created such a deep and compelling impact, and had generated such keen awarenesses of the importance of nutrition as a major determinant of public health, that it became imperative that McCarrison's legacy be fostered, and the good work that he had initiated continued. McCarrison's Deficiency Diseases Enquiry, therefore logically became the forerunner of the Nutrition Research Laboratories of Coonoor, ably guided in succeeding years by Aykroyd, Passmore (who is
*Lecture delivered to The McCarrison Society Scottish Group, Glasgow, Scotland, 23 November 1991. tDr Gopalan is President of the Nutrition Foundation of India, B-37 Gulmohar Park, New Delhi-110049, India.
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happily with us today) and Patwardhan. The Nutrition Research Laboratories later blossomed into the National Institute of Nutrition,. Hyderabad, which I had the privilege of heading for nearly 15 fruitful years. Nutrition Research in India had not only served to enrich Nutrition Science, but had also provided many practical leads for the alleviation of malnutrition among poor communities in India. I believe that this is largely because the McCarrison tradition continued to inform, inspire and influence the pattern of nutrition research in India. Thanks to the great start that McCarrison had provided, Nutrition Research had always enjoyed primacy in India's Medical Research agenda; and the National Institute of Nutrition even today continues to be the largest, and perhaps most prestigious, National Laboratory funded by the Indian Council of Medical Research. McCarrison's place in history, however, does not entirely rest on his contributions to nutrition research in India. McCarrison's contributions to . Nutrition Science are of global significance and entitle him to a place on par with such pioneers as McCollum and Hopkins. In a sense, along with others, McCarrison laid the foundation for modern Nutrition Science itself. McCarrison also had other claims to greatness. He was as much a humanist as he was a scientist. I met him and Mrs. McCarrison at their home in Oxford in 1949, at the conclusion of my tenure as Nuffield Research Fellow at the Medical Research Council in this country, and I cherish the memory of the two hours I spent with them. It became clear to me then, that McCarrison had always looked upon nutrition research in India not as a curiosityoriented academic exercise but as a ne,;;essary contribution for the alleviation of human misery. Indeed all his work in India, which was a predominantly laboratory experimental exercise, was informed by this humanism. McCarrison's work covered a rather wide field and included, apart from work on nutritive value of different diets, investigations on the pathogenesis of goitre, urinary lithiasis, lathyrism and a host of other problems related to nutrition. All this work was done almost single handed, and with no sophisticated equipment of the kind available to researchers of today. Any critical evaluation of McCarrison's work done over 60 years ago under these conditions must take note of these facts. Some ofMcCarrison's conclusions may now be challenged in the light of information and knowledge that has accrued during the last few decades. What is amazing however is that much of what he discovered and claimed, has stood the test of time and continues to be valid even to this day. The conclusions he had set out, and the notes of caution he had sounded over six decades ago, are still so appropriate as to seem almost prophetic. It will be impossible for me to do full justice to the wide range of studies that McCarrison had undertaken. The series of ten successive papers on "The Pathogenesis of Deficiency Disease" 1 which appeared in the Indian Journal of Medical Research in 1919 and 1920, probably represent the
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earliest comprehensive studi(:s on the histopathology of experimentally induced dietary deficiency and served to demonstrate the wide-ranging structural changes in body tissues that nutritional deprivation could induce. (His book on "Studies in Deficiency Disease" 2 is probably among the first major books on the subject of Nutrition to be published; It is astonishing that despite all the sophisticated research of the last few decades, there are very few statements in that book which now need to be changed or challenged) Indeed there were few areas in the area of undernutrition that McCarrison's vast reaching sweep did not touch. However for our present purpose I will refer to only a few of his major observations which are of relevance even to this day. REGIONAL DIFFERENCES Il\' INDIAN DIETS AND THEIR NUTRITIONAL IMPLICATIONS
Perhaps the work of McCarrison 3 that attracted the widest public attention in India was his vivid and striking demonstration of the fact that the wide differences with respect to body-build and stature, that then existed as between (what he called) "the stalwart races of the North oflndia (Panjabis) and the less vigorous races" of the South and East (Bengal), were predominantly attributable to differences in the nutritive values of their respective habitual diets-this, over sixty-five years ago, at a time when Nutrition Science was still very much in its infancy. McCarrison maintained different groups of rats in his laboratory on diets which were closely similar to the habitual diets of Panjab, Bengal, Maharashtra and South India and demonstrated striking differences with respect to body size, body weights, survival and reproduction as between the different groups, with the rats on the "Panjab diet" right on top and those on the "poor south Indian diet" right at the bottom. A big photograph of the pictures of these rats arranged in the descending order of their body size was prominently displayed in the museums of the Nutrition Research Laboratories, Coonoor, and of the National Institute of Nutrition, Hyderabad, for several years, and was always a big draw among their numerous visitors. Perhaps no single experiment could have demonstrated so simply and so vividly the effects of diet on growth and body build. McCarrison argued 3 that "those Indian races like the Sikhs whose diet consists of whole wheat (Chapatties ), sprouted grains, milk, milk products, green leafy vegetables and fruits, with meat occasionally, provide examples of the highest type of physical efficiency met with in this country (India), or indeed in any part of the World. The conclusion was drawn that this is due, in the main, to the high nutritive value of wheat as compared with other staple food-grains, such as rice; and to the manner in which wheat is combined by wheat-eating races with other "protective" and "vitamin A containing foods".
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McCarrison went on to conclude "that a diet of whole wheat, sprouted grain, milk, milk products and green leafy vegetables, with meat occasionally is one on which the omnivorous rat flourishes best; and if we are to judge by the races of India themselves, this diet is one on which Indians flourish best and attain the highest degree of physical efficiency"-a level of efficiency which he had earlier described as being also the highest met with "in any part of the world". It is interesting and important to note that the stock rats in McCarrison's Colony which according to him "flourished best", were on an almost totally lacto-vegetarian diet receiving meat in their diet on just two days in the month. We will revert to this observation later. McCarrison's observations carry several important messages. His observations provided a convincing scientific explanation for the striking differences in the regional distribution of florid nutritional deficiency diseases in India. Vitamin A deficiency, including its most severe form keratomalacia, has always been known to be predominantly a disease of the rice-belt of the country stretching from Bengal and Assam in the east, down along the eastern sea-board of South India. Cases of keratomalacia have hardly ever been encountered in Punjab. Beri Beri of the cardiac and dry type was again mostly confined to the coast of Andhra Pradesh, part of the rice-belt. Also, such manifestations of vitamin B complex deficiency as "orogenital syndrome", "Burning-feet syndrome" and nutritional neuropathies, were always diseases of the country's rice-belt. Kwashiorkor and the more severe forms of protein-energy malnutrition (PEM) were more prominently seen in the rice-belt. Indeed, but for goitre of predominantly sub-Himalayan distribution, and osteomalacia, earlier generally seen among women observing purdha, nutritional deficiency problems on a public health scale were always rare in the North. McCarrison did not stop with demonstrating the fact that the different regional diets of India could bring about differences in levels of growth and body size. He proceeded to elucidate the precise nature of differences with respect to nutrients between the different diets. THE "SUPERIORITY OF WHOLE WHEAT"
McCarrison like McCay who preceded him was deeply convinced of the superiority of wheat over other staple cereals of India. McCay4-who attributed the superior nutritional value of wheat to its higher protein content, had claimed: "an intimate connection exists between the physical development and well-being of people and the level of nitrogenous interchange they attain; that wheat provides a protein of better quality than rice or other cereals in common use in India, that the composition of the wheat eaters' diet admits of the absorption of a larger amount of protein and of the attainment of a higher level of nitrogenous exchange than is possible
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in rice-eaters". McCay had concluded "that the wheat-eater is better developed physically, more capable of hard work, hardier and more alive than the average (rice-eater) of the same class". However McCay went so far as to claim: "The proteins of wheat are a little more efficient for the promotion of growth than are the same amounts of proteins from milk or eggs!"-a statement that would now evoke consternation among nutrition scientists. It is a tribute to McCarrison's scientific acumen, that while generally endorsing the nutritional superiority of wheat over other cereals, he dissociated himself from the exaggerated position taken by McCay with these words: "His.(McCay's) work was done, however, at a time when the newer knowledge of nutrition had yet to be acquired, and his conclusion would nowadays be modified to include other factors (vitamins and minerals) which play their part, equally with protein of good biological value, in bringing about the highest physical efficiency· of certain Indian races". 5 That this balanced assessment of McCarrison's which cannot be faulted even in the light of the most recent knowledge in Nutrition was made nearly 65 years ago is a tribute to his vision and commonsense. CHEMICAL COMPOSITION OF CEREALS
McCarrison's claims as to the better nutritive value of wheat did not rest entirely on the results of his studies of growth of rats in his laboratory animal colony. He had also carried out elaborate comparative chemical analysis of the four staple food grains in general use in India (table 1) and concluded that apart from differences with respect to protein content, the higher TABLE I
Results of analysis of staple cereals Constituents Crude Protein Crude fibre Carbohydrate Mineral matter Phosphoric acid Iron Oxide Lime Magnesia Manganese
Wheat
Cambu*
Cholam**
%
%
%
%
12.87 1.81 68.71 2.22 0.70 0.04 0.02 0,078 0.0049
10.58 1.58 69.77 1.68 0.73 0.022 0.05 0.067
8.59 0.28 77.19 1.25 0.52 0.042 0.022 0.0694 0.0033
12.09 2.20 67.92 2.34 1.14 0.23 0.094 0.133 0.124
Paddy (Rice)
Source: McCarrison, R. The nutritive values of wheat, paddy and certain other food grains.
Indian Journal of Medical Research. 1927. Vol. 14, p 631-639. *-Pennisetum typhoideum (millet) **-Sorghum vulgare (millet)
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content of some minerals in wheat might have also contributed to its better nutritive value. 5 McCarrison, in particular, seemed to favour the view that the superiority of wheat may also be partly due to its higher content of manganese-a point to which we will return later~
WHOLE 'WHEAT BREAD' AND 'WHITE BREAD'-A COMPARISON
McCarrison's work had also provided an indication of the very significant losses in nutritive value that food grains could suffer due to "processing". McCarrison sounded his note of caution against possible depletion of nutritive value of foods through excessive processing even at a time when processing technology was in its infancy. He compared6 the chemical composition of whole wheat and white flour (table 2) and pointed out: "The wheat grain consists of the endosperm, the germ and the pericarp and integuments or outermost layers of the seed. The carbohydrates are contained chiefly in the endosperm, which white flour mainly consists of; the germ contains the fat, while the proteins, vitamins, fibre and inorganic salts largely reside in the germ and bran. With the removal of the germ, pericap and integuments involved in the manufacture of white flour, much of the fat, protein, mineral matter, vitamins and crude fibre are lost. Of these losses, the most serious are those of proteins, of salts, of vitamin and or crude fibre". McCarrison further emphasised the fact that the loss of protein in white TABLE 2 Chemical composition of the whole wheat and the white flour (expressed in percentages of moisture-free sample) Constituents Crude proteins Crude fibre Carbohydrates Mineral Matter: Insoluble Soluble Soluble mineral matter Phosphoric acid Iron oxide Manganese Lime Magnesia Potash
Whole wheat flour
White flour
13.61 1.991 79.599
9.63 0.50 88.155
0.43 2.008
0.016 0.455
0.960 0.04 0.0086 0.22 0.247 0.343
0.002
Trace 0.0008 0.09
Trace 0.08
Source: McCarrison, R. Whole wheat bread and white bread: A comparative study. Indian Journal of Medical Research, 1930 Vol XVII, No. 3, p 667-692.
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flour represented not just a reduction in the overall quantity of protein but also an impairment of protein quality because what was lost in the discarding of the germ and bran was protein of better quality, necessitating the incorporation of other "expensive" sources of protein such as milk, meat and eggs. Special attention needs to be drawn to McCarrison's emphasis on the importance of crude fibre as a necessary dietary component, at a time when it was largely being dismissed from the nutritional point of view as just "roughage". The meticulous scientist that he was, McCarrison did not stop with just chemical analysis of whole wheat bread and white bread to demonstrate the loss of nutritive value in the latter. He carried out studies on the effects of diets based exclusively on white flour and on "atta" (whole flour), and demonstrated the striking differences in growth, survival and susceptibility to polyneuritis in the two groups of animals. In a further extension of these studies, McCarrison com pared the effects of feeding a "good diet" based on whole wheat (Chappaties) milk, milk-products, sprouted grains and green leafy-vegetables and a "bad diet" which he described as one being then eaten by many "western people of poor classes" based on white bread "made from American white flour" (fig 1). McCarrison was apparently deeply disturbed by the fact that the food preservatives widely used in western countries then were boric acid and formaldehyde. 3 He had estimated that as much as 175, 140 and 110 grains per pound of boric acid were being used in margarine, butter and bacon respectively. With a diet based on white bread, vegetables and margarine containing boric acid in the concentration used as a preservative; he found marked differences in growth and mortality rate. McCarrison's studies always included careful histopathology of different organs. An important finding of this study was that animals on the "bad diet" exhibited pathological changes in the gastrointestinal tract and had suffered bronchoneumonia 3 exceedingly rare in the animals on the whole-wheat diet, and the stock diet. McCarrison concluded: "The high incidence of lung disease in the ill-fed group ("bad diet") emphasises, strikingly, the influence of what one may call the white bread-margarine, tea diet "favouring the operation of pathogenic agents which attack the lungs". This was probably among the very first observations linking undernutrition with susceptibility to infections on the basis of carefully controlled observations. McCarrison's paper written in 19197 on "The influence of deficiency of accessory food factors on the intestine" published in the British Medical Journal served to demonstrate that such deprivation led to congestive and atrophic changes in coats of the bowel, to lesions of its neuromuscular mechanism, to impairment of digestive and assimilation processes, and to failure of protective resources against infection. He concluded on the basis of these studies: "certain gastrointestinal disorders in the human subject may owe their origin to subminimal supply of accessory food factors protracted over long periods of time".
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Rat fed for approximately six months on the good diet.
Rat of the same age fed for approximately six months on the 'bad diet'. Figure I.
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In a remarkable experiment 5 McCarrison demonstrated that the superiority of wheat over other cereals depended not only on its better protein content, but also on its better content of "accessory factors". For this study, he chose what he called a "basal diet" containing "meat residue", purified starch, olive oil and salt mixture. Animals in all groups received this basal diet. The animals were divided into groups- each group receiving in addition to the basal diet just one gram of the grain to be tested: wheat, Cambu, Cholam or Paddy. For comparison he also had animals on the stock diet and animals receiving in addition to the basal diet, either cod-liver oil, marmite or both. These experiments (fig 2), surprisingly, showed that rats receiving the basal diet plus wheat, the latter just as a small supplement, were not only better off than those who received the same level of
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supplement of other cereals, but, were also better off than those which had received supplements of cod liver oil and marmite, thus underscoring the role of "protective factors" in wheat. As was pointed out earlier McCarrison attributed the superiority of the physical status of the Panjabi's as compared to the people of the East and South India not to wheat alone (in preference to rice) but to the manner in which the Panjabi combined this wheat with other "protective foods". Increased intake of milk, pulses (legumes) and leafy vegetables (as compared to intake in the East and South) are as much a part of the Panjabi dietary culture as the preference for wheat. Regional dietary differences in India have narrowed somewhat during the five decades that have elapsed since McCarrison 's work, perhaps because of better communication and transport, and increasing urbanisation. The Bengali and the South Indians are not as averse to wheat as they were five decades ago, and rice now figures increasingly in the Panjabi diet. With the advent of the Green Revolution, the production and consumption of both wheat and rice has increased both in the North and South; the cereals which have not benefited from the Green Revolution are the millets-the poor man's staple; habitual millet eaters are increasingly switching over to rice and wheat; pulses which served to raise the protein quality of Indian diets have suffered a near-total neglect. It is however, apparently, still the case that milk, vegetable and fruit consumption in the North exceeds that in the South and East, and the nutritive value of the average diet of the Panjab is still somewhat superior to that of the South and East. The plea for inclusion of more milk, pulses and green leafy vegetables especially in the relatively poorer South Indian and Bengali dietaries is as valid today as it was in McCarrison's time. It is most unfortunate that with an abundance of carotene-rich green leafy vegetables right at their own door-steps, children of poor communities in these parts of the country (under international advice and multinational pressure), are now sought to be administered periodic massive doses of synthetic vitamin A to ward off vitamin A deficiency! What is even more strange and perverse, the children of the Panjab and the rest of the country where vitamin A deficiency is no serious public health problem are not being spared this international and multinational "onslaught" with periodic massive doses of synthetic vitamin A. McCarrison would most certainly have raised his voice against these aberrations and would have forcefully pleaded for a sensible use of the abundant natural food resources to improve the nutritional status of India's poor communities. MERITS OF A LACTO-VEGETARIAN (LOW-MEAT) DIET
The diet which McCarrison obviously considered best was one based on whole wheat, and containing sprouted grain, milk and milk products, green
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leafy vegetables and meat occasionally. McCarrison claimed that the "omnivorous" rat in his stock colony "flourished best" on such a diet which provided meat on only two days in a month. He considered this lactovegetarian diet as one which permitted the attainment of "the highest degree of physical efficiency". McCarrison's repeated assertion of the nutritional merits of such a predominantly lacto-vegetarian diet with little or no meat in it, carries the important message that human beings can achieve the highest level of physical efficiency, and find full expression to their genetic potential for growth and productivity on diets which are based on wholesome cereals, legumes, vegetables and fruits and adequate amounts of milk, with little or no meat. Some European (especially East Europeans) and some American diets today provide an intake of protein which exceeds 1OOg/day, most of it derived from animal sources. Much of this precious nitrogen is now being wastefully excreted and washed down the toilets. The question that arises is whether such high levels of intake of meat are at all necessary? Are they not wasteful and do they not constitute an improvident and imprudent use of world's natural food resources? Indeed the question arises, are such high meat intakes conducive to good health, since excess protein has necessarily to be metabolised and excreted? Does not such high intakes of protein entail an unnecessarily greater metabolic load on the organs involved in the metabolism and excretion of protein? McCarrison's studies need not necessarily be interpreted as justifying advocacy of total strict vegetarianism; but they certainly provide valid evidence against the need for current excessive intakes of meat in some European and North American diets. Recent studies have also indicated some other advantages of a predominantly vegetarian diet such as its high fibre content (a point to which McCarrison had made a reference), its ability to promote and sustain a favourable serum lipid profile beneficial for cardio vascular health etc. MANGANESE AND GROWTH
The importance of trace elements in nutrition was not recognised at the time of McCarrison. The emphasis was largely on the proximate principles and on vitamins. Standard books on Nutrition 8 claim that the essentiality of manganese as a trace element was tirst reported in experimental animals in 1931. Actually it was first suggested by Levine and Sohm in 19249 and convincingly demonstrated in experimental animals by McCarrison in 1926. 10 McCarrison reported that whole wheat, unlike rice, was a good source of manganese containing 3.9 to 4.8 ug per 100 g of the dry material, the manganese being concentrated in the outerlayers and therefore largely removed in the process of manufacture of white flour. McCarrison also reported on the manganese concentrations in animal tissues.
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In experimental studies on rats, McCarrison showed that while at higher levels manganese was deleterious, at lower levels (of 1 part in 617,700 of the food eaten daily) manganese (given as Mn C12) had a distinct growth promoting effect (Fig 3). McCarrison argued that the nutritional superiority of whole wheat over rice was probably partly due to its higher manganese content (rice being a poor source). · I draw attention to this work not because I consider this as among McCarrison's major contributions of practical importance, but merely to illustrate the meticulousness of his studies. The importance of trace elements like manganese was barely suspected in the twenties of this century. In recent years however the wide ranging metabolic role of manganese, in the regulation of carbohydrate and lipid metabolism and as a cofactor or as an integral part of important metallo-enzymes has been recognised. 11
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IMPACT OF AGRICULTURAL TECHNOLOGY ON NUTRITIVE VALUE OF FOODS Perhaps an area of nutrition science, more than any other, in which McCarrison was far ahead of his times, was with respect to the effect of soil conditions and soil management, on the nutritive value offoodsgrown. His papers on the influence of irrigation on the nutritive values of rice 12 and on the effect of manurial conditions on the nutritive values of millet and wheat 13 had not perhaps attracted the same attention that his other papers on the nutritive value of regional dietaries in India had done: but in the context of present better appreciation of possible repercussions of modern intensive agricultural technology on yield and nutritive value of food grains, his observations in this area are of considerable contemporary relevance. India, and many developing countries, in their anxiety to augment foodgrain production to meet the food needs of their rapidly growing populations, have opted heavily for modern agricultural technology. The use of HYV and chemical fertilizers have no doubt yielded gratifying results in the short run. Overall food-grain production has increased to levels which have helped to ensure that per-capita food grain availability has not declined despite population growth. But it now appears that the Green Revolution, despite its immediate spectacular benefits, may have extracted a heavy price. Ambitious irrigation projects and unregulated deforestation have contributed to frequent flooding and progressive salination and alkalisation of erstwhile fertile agricultural soils. Attempts at periodical soil testing and soil replenishment have not gone hand in hand with the adoption of intensive agricultural technology. The result has been that there is an alarming indication of decline in productivity of land. Apart from water-logging and flooding, the intensive use of high analysis chemical fertilizers (which are totally free of micronutrients ), the near-total jettisoning of organic manures, the resort to monocropping, and the virtual abandonment of traditional systems of crop-rotation, and the neglect of leguminous crop, have all combined to bring about a progressive depletion of essential micronutrients of the soil-essential for ensuring the adequate productivity and yield of lands on the one hand, and for ensuring adequate concentrations of micronutrients in the foods needed for human nutrition on the other. Global studies of micronutrient depletion of soils carried out recently by FA0 14 •15 reveal an alarming picture of micronutrient depletion of soils and foods. Such essential soil micronutrients as Zn, Fe, Mn and Cu show evidence of depletion. According to a recent report 53% of both soils and crops in Andhra Pradesh, 50% in Panjab and 64% in Haryana in India are deficient in zinc and manganese. 16 As early as in 1926, 13 McCarrison had cautioned: "Many millions of people in this country (India) restrict themselves to a single cereal as the staple article of the dietary. Their physical efficiency is so largely dependent on the quality of their staple food grain that it is necessary to be aware of the
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FOOD AND HEALTH-McCARRISON'S PRESCRIPTION ENDURES* C. GOPALANt The Nutrition Foundation of India
It is indeed an honour and privilege for me to have this opportunity to pay my homage and tribute to Sir Robert McCarrison, a great and distinguished scientist. McCarrison, undoubtedly, laid the foundation for nutrition research in India. The Deficiency Diseases Enquiry (of the Indian Research Fund Association) which he founded and headed with rare devotion and dedication for nearly two decades in the earlier half of this century, was, by current standards, a small unit with limited staff and equipment. However, the string of publications in successive volumes of the Indian Journal of Medical Research for over a decade starting from 1919 bear ample testimony to the quality, range and output ofMcCarrison's pioneering work during this period. That work had created such a deep and compelling impact, and had generated such keen awarenesses of the importance of nutrition as a major determinant of public health, that it became imperative that McCarrison's legacy be fostered, and the good work that he had initiated continued. McCarrison's Deficiency Diseases Enquiry, therefore logically became the forerunner of the Nutrition Research Laboratories of Coonoor, ably guided in succeeding years by Aykroyd, Passmore (who is
*Lecture delivered to The McCarrison Society Scottish Group, Glasgow, Scotland, 23 November 1991. tDr Gopalan is President of the Nutrition Foundation of India, B-37 Gulmohar Park, New Delhi-110049, India.
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2
happily with us today) and Patwardhan. The Nutrition Research Laboratories later blossomed into the National Institute of Nutrition,. Hyderabad, which I had the privilege of heading for nearly 15 fruitful years. Nutrition Research in India had not only served to enrich Nutrition Science, but had also provided many practical leads for the alleviation of malnutrition among poor communities in India. I believe that this is largely because the McCarrison tradition continued to inform, inspire and influence the pattern of nutrition research in India. Thanks to the great start that McCarrison had provided, Nutrition Research had always enjoyed primacy in India's Medical Research agenda; and the National Institute of Nutrition even today continues to be the largest, and perhaps most prestigious, National Laboratory funded by the Indian Council of Medical Research. McCarrison's place in history, however, does not entirely rest on his contributions to nutrition research in India. McCarrison's contributions to . Nutrition Science are of global significance and entitle him to a place on par with such pioneers as McCollum and Hopkins. In a sense, along with others, McCarrison laid the foundation for modern Nutrition Science itself. McCarrison also had other claims to greatness. He was as much a humanist as he was a scientist. I met him and Mrs. McCarrison at their home in Oxford in 1949, at the conclusion of my tenure as Nuffield Research Fellow at the Medical Research Council in this country, and I cherish the memory of the two hours I spent with them. It became clear to me then, that McCarrison had always looked upon nutrition research in India not as a curiosityoriented academic exercise but as a ne,;;essary contribution for the alleviation of human misery. Indeed all his work in India, which was a predominantly laboratory experimental exercise, was informed by this humanism. McCarrison's work covered a rather wide field and included, apart from work on nutritive value of different diets, investigations on the pathogenesis of goitre, urinary lithiasis, lathyrism and a host of other problems related to nutrition. All this work was done almost single handed, and with no sophisticated equipment of the kind available to researchers of today. Any critical evaluation of McCarrison's work done over 60 years ago under these conditions must take note of these facts. Some ofMcCarrison's conclusions may now be challenged in the light of information and knowledge that has accrued during the last few decades. What is amazing however is that much of what he discovered and claimed, has stood the test of time and continues to be valid even to this day. The conclusions he had set out, and the notes of caution he had sounded over six decades ago, are still so appropriate as to seem almost prophetic. It will be impossible for me to do full justice to the wide range of studies that McCarrison had undertaken. The series of ten successive papers on "The Pathogenesis of Deficiency Disease" 1 which appeared in the Indian Journal of Medical Research in 1919 and 1920, probably represent the
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earliest comprehensive studi(:s on the histopathology of experimentally induced dietary deficiency and served to demonstrate the wide-ranging structural changes in body tissues that nutritional deprivation could induce. (His book on "Studies in Deficiency Disease" 2 is probably among the first major books on the subject of Nutrition to be published; It is astonishing that despite all the sophisticated research of the last few decades, there are very few statements in that book which now need to be changed or challenged) Indeed there were few areas in the area of undernutrition that McCarrison's vast reaching sweep did not touch. However for our present purpose I will refer to only a few of his major observations which are of relevance even to this day. REGIONAL DIFFERENCES Il\' INDIAN DIETS AND THEIR NUTRITIONAL IMPLICATIONS
Perhaps the work of McCarrison 3 that attracted the widest public attention in India was his vivid and striking demonstration of the fact that the wide differences with respect to body-build and stature, that then existed as between (what he called) "the stalwart races of the North oflndia (Panjabis) and the less vigorous races" of the South and East (Bengal), were predominantly attributable to differences in the nutritive values of their respective habitual diets-this, over sixty-five years ago, at a time when Nutrition Science was still very much in its infancy. McCarrison maintained different groups of rats in his laboratory on diets which were closely similar to the habitual diets of Panjab, Bengal, Maharashtra and South India and demonstrated striking differences with respect to body size, body weights, survival and reproduction as between the different groups, with the rats on the "Panjab diet" right on top and those on the "poor south Indian diet" right at the bottom. A big photograph of the pictures of these rats arranged in the descending order of their body size was prominently displayed in the museums of the Nutrition Research Laboratories, Coonoor, and of the National Institute of Nutrition, Hyderabad, for several years, and was always a big draw among their numerous visitors. Perhaps no single experiment could have demonstrated so simply and so vividly the effects of diet on growth and body build. McCarrison argued 3 that "those Indian races like the Sikhs whose diet consists of whole wheat (Chapatties ), sprouted grains, milk, milk products, green leafy vegetables and fruits, with meat occasionally, provide examples of the highest type of physical efficiency met with in this country (India), or indeed in any part of the World. The conclusion was drawn that this is due, in the main, to the high nutritive value of wheat as compared with other staple food-grains, such as rice; and to the manner in which wheat is combined by wheat-eating races with other "protective" and "vitamin A containing foods".
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McCarrison went on to conclude "that a diet of whole wheat, sprouted grain, milk, milk products and green leafy vegetables, with meat occasionally is one on which the omnivorous rat flourishes best; and if we are to judge by the races of India themselves, this diet is one on which Indians flourish best and attain the highest degree of physical efficiency"-a level of efficiency which he had earlier described as being also the highest met with "in any part of the world". It is interesting and important to note that the stock rats in McCarrison's Colony which according to him "flourished best", were on an almost totally lacto-vegetarian diet receiving meat in their diet on just two days in the month. We will revert to this observation later. McCarrison's observations carry several important messages. His observations provided a convincing scientific explanation for the striking differences in the regional distribution of florid nutritional deficiency diseases in India. Vitamin A deficiency, including its most severe form keratomalacia, has always been known to be predominantly a disease of the rice-belt of the country stretching from Bengal and Assam in the east, down along the eastern sea-board of South India. Cases of keratomalacia have hardly ever been encountered in Punjab. Beri Beri of the cardiac and dry type was again mostly confined to the coast of Andhra Pradesh, part of the rice-belt. Also, such manifestations of vitamin B complex deficiency as "orogenital syndrome", "Burning-feet syndrome" and nutritional neuropathies, were always diseases of the country's rice-belt. Kwashiorkor and the more severe forms of protein-energy malnutrition (PEM) were more prominently seen in the rice-belt. Indeed, but for goitre of predominantly sub-Himalayan distribution, and osteomalacia, earlier generally seen among women observing purdha, nutritional deficiency problems on a public health scale were always rare in the North. McCarrison did not stop with demonstrating the fact that the different regional diets of India could bring about differences in levels of growth and body size. He proceeded to elucidate the precise nature of differences with respect to nutrients between the different diets. THE "SUPERIORITY OF WHOLE WHEAT"
McCarrison like McCay who preceded him was deeply convinced of the superiority of wheat over other staple cereals of India. McCay4-who attributed the superior nutritional value of wheat to its higher protein content, had claimed: "an intimate connection exists between the physical development and well-being of people and the level of nitrogenous interchange they attain; that wheat provides a protein of better quality than rice or other cereals in common use in India, that the composition of the wheat eaters' diet admits of the absorption of a larger amount of protein and of the attainment of a higher level of nitrogenous exchange than is possible
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in rice-eaters". McCay had concluded "that the wheat-eater is better developed physically, more capable of hard work, hardier and more alive than the average (rice-eater) of the same class". However McCay went so far as to claim: "The proteins of wheat are a little more efficient for the promotion of growth than are the same amounts of proteins from milk or eggs!"-a statement that would now evoke consternation among nutrition scientists. It is a tribute to McCarrison's scientific acumen, that while generally endorsing the nutritional superiority of wheat over other cereals, he dissociated himself from the exaggerated position taken by McCay with these words: "His.(McCay's) work was done, however, at a time when the newer knowledge of nutrition had yet to be acquired, and his conclusion would nowadays be modified to include other factors (vitamins and minerals) which play their part, equally with protein of good biological value, in bringing about the highest physical efficiency· of certain Indian races". 5 That this balanced assessment of McCarrison's which cannot be faulted even in the light of the most recent knowledge in Nutrition was made nearly 65 years ago is a tribute to his vision and commonsense. CHEMICAL COMPOSITION OF CEREALS
McCarrison's claims as to the better nutritive value of wheat did not rest entirely on the results of his studies of growth of rats in his laboratory animal colony. He had also carried out elaborate comparative chemical analysis of the four staple food grains in general use in India (table 1) and concluded that apart from differences with respect to protein content, the higher TABLE I
Results of analysis of staple cereals Constituents Crude Protein Crude fibre Carbohydrate Mineral matter Phosphoric acid Iron Oxide Lime Magnesia Manganese
Wheat
Cambu*
Cholam**
%
%
%
%
12.87 1.81 68.71 2.22 0.70 0.04 0.02 0,078 0.0049
10.58 1.58 69.77 1.68 0.73 0.022 0.05 0.067
8.59 0.28 77.19 1.25 0.52 0.042 0.022 0.0694 0.0033
12.09 2.20 67.92 2.34 1.14 0.23 0.094 0.133 0.124
Paddy (Rice)
Source: McCarrison, R. The nutritive values of wheat, paddy and certain other food grains.
Indian Journal of Medical Research. 1927. Vol. 14, p 631-639. *-Pennisetum typhoideum (millet) **-Sorghum vulgare (millet)
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content of some minerals in wheat might have also contributed to its better nutritive value. 5 McCarrison, in particular, seemed to favour the view that the superiority of wheat may also be partly due to its higher content of manganese-a point to which we will return later~
WHOLE 'WHEAT BREAD' AND 'WHITE BREAD'-A COMPARISON
McCarrison's work had also provided an indication of the very significant losses in nutritive value that food grains could suffer due to "processing". McCarrison sounded his note of caution against possible depletion of nutritive value of foods through excessive processing even at a time when processing technology was in its infancy. He compared6 the chemical composition of whole wheat and white flour (table 2) and pointed out: "The wheat grain consists of the endosperm, the germ and the pericarp and integuments or outermost layers of the seed. The carbohydrates are contained chiefly in the endosperm, which white flour mainly consists of; the germ contains the fat, while the proteins, vitamins, fibre and inorganic salts largely reside in the germ and bran. With the removal of the germ, pericap and integuments involved in the manufacture of white flour, much of the fat, protein, mineral matter, vitamins and crude fibre are lost. Of these losses, the most serious are those of proteins, of salts, of vitamin and or crude fibre". McCarrison further emphasised the fact that the loss of protein in white TABLE 2 Chemical composition of the whole wheat and the white flour (expressed in percentages of moisture-free sample) Constituents Crude proteins Crude fibre Carbohydrates Mineral Matter: Insoluble Soluble Soluble mineral matter Phosphoric acid Iron oxide Manganese Lime Magnesia Potash
Whole wheat flour
White flour
13.61 1.991 79.599
9.63 0.50 88.155
0.43 2.008
0.016 0.455
0.960 0.04 0.0086 0.22 0.247 0.343
0.002
Trace 0.0008 0.09
Trace 0.08
Source: McCarrison, R. Whole wheat bread and white bread: A comparative study. Indian Journal of Medical Research, 1930 Vol XVII, No. 3, p 667-692.
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flour represented not just a reduction in the overall quantity of protein but also an impairment of protein quality because what was lost in the discarding of the germ and bran was protein of better quality, necessitating the incorporation of other "expensive" sources of protein such as milk, meat and eggs. Special attention needs to be drawn to McCarrison's emphasis on the importance of crude fibre as a necessary dietary component, at a time when it was largely being dismissed from the nutritional point of view as just "roughage". The meticulous scientist that he was, McCarrison did not stop with just chemical analysis of whole wheat bread and white bread to demonstrate the loss of nutritive value in the latter. He carried out studies on the effects of diets based exclusively on white flour and on "atta" (whole flour), and demonstrated the striking differences in growth, survival and susceptibility to polyneuritis in the two groups of animals. In a further extension of these studies, McCarrison com pared the effects of feeding a "good diet" based on whole wheat (Chappaties) milk, milk-products, sprouted grains and green leafy-vegetables and a "bad diet" which he described as one being then eaten by many "western people of poor classes" based on white bread "made from American white flour" (fig 1). McCarrison was apparently deeply disturbed by the fact that the food preservatives widely used in western countries then were boric acid and formaldehyde. 3 He had estimated that as much as 175, 140 and 110 grains per pound of boric acid were being used in margarine, butter and bacon respectively. With a diet based on white bread, vegetables and margarine containing boric acid in the concentration used as a preservative; he found marked differences in growth and mortality rate. McCarrison's studies always included careful histopathology of different organs. An important finding of this study was that animals on the "bad diet" exhibited pathological changes in the gastrointestinal tract and had suffered bronchoneumonia 3 exceedingly rare in the animals on the whole-wheat diet, and the stock diet. McCarrison concluded: "The high incidence of lung disease in the ill-fed group ("bad diet") emphasises, strikingly, the influence of what one may call the white bread-margarine, tea diet "favouring the operation of pathogenic agents which attack the lungs". This was probably among the very first observations linking undernutrition with susceptibility to infections on the basis of carefully controlled observations. McCarrison's paper written in 19197 on "The influence of deficiency of accessory food factors on the intestine" published in the British Medical Journal served to demonstrate that such deprivation led to congestive and atrophic changes in coats of the bowel, to lesions of its neuromuscular mechanism, to impairment of digestive and assimilation processes, and to failure of protective resources against infection. He concluded on the basis of these studies: "certain gastrointestinal disorders in the human subject may owe their origin to subminimal supply of accessory food factors protracted over long periods of time".
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Rat fed for approximately six months on the good diet.
Rat of the same age fed for approximately six months on the 'bad diet'. Figure I.
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In a remarkable experiment 5 McCarrison demonstrated that the superiority of wheat over other cereals depended not only on its better protein content, but also on its better content of "accessory factors". For this study, he chose what he called a "basal diet" containing "meat residue", purified starch, olive oil and salt mixture. Animals in all groups received this basal diet. The animals were divided into groups- each group receiving in addition to the basal diet just one gram of the grain to be tested: wheat, Cambu, Cholam or Paddy. For comparison he also had animals on the stock diet and animals receiving in addition to the basal diet, either cod-liver oil, marmite or both. These experiments (fig 2), surprisingly, showed that rats receiving the basal diet plus wheat, the latter just as a small supplement, were not only better off than those who received the same level of
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lO
supplement of other cereals, but, were also better off than those which had received supplements of cod liver oil and marmite, thus underscoring the role of "protective factors" in wheat. As was pointed out earlier McCarrison attributed the superiority of the physical status of the Panjabi's as compared to the people of the East and South India not to wheat alone (in preference to rice) but to the manner in which the Panjabi combined this wheat with other "protective foods". Increased intake of milk, pulses (legumes) and leafy vegetables (as compared to intake in the East and South) are as much a part of the Panjabi dietary culture as the preference for wheat. Regional dietary differences in India have narrowed somewhat during the five decades that have elapsed since McCarrison 's work, perhaps because of better communication and transport, and increasing urbanisation. The Bengali and the South Indians are not as averse to wheat as they were five decades ago, and rice now figures increasingly in the Panjabi diet. With the advent of the Green Revolution, the production and consumption of both wheat and rice has increased both in the North and South; the cereals which have not benefited from the Green Revolution are the millets-the poor man's staple; habitual millet eaters are increasingly switching over to rice and wheat; pulses which served to raise the protein quality of Indian diets have suffered a near-total neglect. It is however, apparently, still the case that milk, vegetable and fruit consumption in the North exceeds that in the South and East, and the nutritive value of the average diet of the Panjab is still somewhat superior to that of the South and East. The plea for inclusion of more milk, pulses and green leafy vegetables especially in the relatively poorer South Indian and Bengali dietaries is as valid today as it was in McCarrison's time. It is most unfortunate that with an abundance of carotene-rich green leafy vegetables right at their own door-steps, children of poor communities in these parts of the country (under international advice and multinational pressure), are now sought to be administered periodic massive doses of synthetic vitamin A to ward off vitamin A deficiency! What is even more strange and perverse, the children of the Panjab and the rest of the country where vitamin A deficiency is no serious public health problem are not being spared this international and multinational "onslaught" with periodic massive doses of synthetic vitamin A. McCarrison would most certainly have raised his voice against these aberrations and would have forcefully pleaded for a sensible use of the abundant natural food resources to improve the nutritional status of India's poor communities. MERITS OF A LACTO-VEGETARIAN (LOW-MEAT) DIET
The diet which McCarrison obviously considered best was one based on whole wheat, and containing sprouted grain, milk and milk products, green
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leafy vegetables and meat occasionally. McCarrison claimed that the "omnivorous" rat in his stock colony "flourished best" on such a diet which provided meat on only two days in a month. He considered this lactovegetarian diet as one which permitted the attainment of "the highest degree of physical efficiency". McCarrison's repeated assertion of the nutritional merits of such a predominantly lacto-vegetarian diet with little or no meat in it, carries the important message that human beings can achieve the highest level of physical efficiency, and find full expression to their genetic potential for growth and productivity on diets which are based on wholesome cereals, legumes, vegetables and fruits and adequate amounts of milk, with little or no meat. Some European (especially East Europeans) and some American diets today provide an intake of protein which exceeds 1OOg/day, most of it derived from animal sources. Much of this precious nitrogen is now being wastefully excreted and washed down the toilets. The question that arises is whether such high levels of intake of meat are at all necessary? Are they not wasteful and do they not constitute an improvident and imprudent use of world's natural food resources? Indeed the question arises, are such high meat intakes conducive to good health, since excess protein has necessarily to be metabolised and excreted? Does not such high intakes of protein entail an unnecessarily greater metabolic load on the organs involved in the metabolism and excretion of protein? McCarrison's studies need not necessarily be interpreted as justifying advocacy of total strict vegetarianism; but they certainly provide valid evidence against the need for current excessive intakes of meat in some European and North American diets. Recent studies have also indicated some other advantages of a predominantly vegetarian diet such as its high fibre content (a point to which McCarrison had made a reference), its ability to promote and sustain a favourable serum lipid profile beneficial for cardio vascular health etc. MANGANESE AND GROWTH
The importance of trace elements in nutrition was not recognised at the time of McCarrison. The emphasis was largely on the proximate principles and on vitamins. Standard books on Nutrition 8 claim that the essentiality of manganese as a trace element was tirst reported in experimental animals in 1931. Actually it was first suggested by Levine and Sohm in 19249 and convincingly demonstrated in experimental animals by McCarrison in 1926. 10 McCarrison reported that whole wheat, unlike rice, was a good source of manganese containing 3.9 to 4.8 ug per 100 g of the dry material, the manganese being concentrated in the outerlayers and therefore largely removed in the process of manufacture of white flour. McCarrison also reported on the manganese concentrations in animal tissues.
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12
In experimental studies on rats, McCarrison showed that while at higher levels manganese was deleterious, at lower levels (of 1 part in 617,700 of the food eaten daily) manganese (given as Mn C12) had a distinct growth promoting effect (Fig 3). McCarrison argued that the nutritional superiority of whole wheat over rice was probably partly due to its higher manganese content (rice being a poor source). · I draw attention to this work not because I consider this as among McCarrison's major contributions of practical importance, but merely to illustrate the meticulousness of his studies. The importance of trace elements like manganese was barely suspected in the twenties of this century. In recent years however the wide ranging metabolic role of manganese, in the regulation of carbohydrate and lipid metabolism and as a cofactor or as an integral part of important metallo-enzymes has been recognised. 11
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IMPACT OF AGRICULTURAL TECHNOLOGY ON NUTRITIVE VALUE OF FOODS Perhaps an area of nutrition science, more than any other, in which McCarrison was far ahead of his times, was with respect to the effect of soil conditions and soil management, on the nutritive value offoodsgrown. His papers on the influence of irrigation on the nutritive values of rice 12 and on the effect of manurial conditions on the nutritive values of millet and wheat 13 had not perhaps attracted the same attention that his other papers on the nutritive value of regional dietaries in India had done: but in the context of present better appreciation of possible repercussions of modern intensive agricultural technology on yield and nutritive value of food grains, his observations in this area are of considerable contemporary relevance. India, and many developing countries, in their anxiety to augment foodgrain production to meet the food needs of their rapidly growing populations, have opted heavily for modern agricultural technology. The use of HYV and chemical fertilizers have no doubt yielded gratifying results in the short run. Overall food-grain production has increased to levels which have helped to ensure that per-capita food grain availability has not declined despite population growth. But it now appears that the Green Revolution, despite its immediate spectacular benefits, may have extracted a heavy price. Ambitious irrigation projects and unregulated deforestation have contributed to frequent flooding and progressive salination and alkalisation of erstwhile fertile agricultural soils. Attempts at periodical soil testing and soil replenishment have not gone hand in hand with the adoption of intensive agricultural technology. The result has been that there is an alarming indication of decline in productivity of land. Apart from water-logging and flooding, the intensive use of high analysis chemical fertilizers (which are totally free of micronutrients ), the near-total jettisoning of organic manures, the resort to monocropping, and the virtual abandonment of traditional systems of crop-rotation, and the neglect of leguminous crop, have all combined to bring about a progressive depletion of essential micronutrients of the soil-essential for ensuring the adequate productivity and yield of lands on the one hand, and for ensuring adequate concentrations of micronutrients in the foods needed for human nutrition on the other. Global studies of micronutrient depletion of soils carried out recently by FA0 14 •15 reveal an alarming picture of micronutrient depletion of soils and foods. Such essential soil micronutrients as Zn, Fe, Mn and Cu show evidence of depletion. According to a recent report 53% of both soils and crops in Andhra Pradesh, 50% in Panjab and 64% in Haryana in India are deficient in zinc and manganese. 16 As early as in 1926, 13 McCarrison had cautioned: "Many millions of people in this country (India) restrict themselves to a single cereal as the staple article of the dietary. Their physical efficiency is so largely dependent on the quality of their staple food grain that it is necessary to be aware of the
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14
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