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Upgrading nutrient quality

A qualitative dimension to food production was built into Indian agriculture when attempts were begun years ago, to improve the nutritive value of cereals and millets through genetic engineering, made possible by the discovery of genes that control the concentrations of nutrients. Malnutrition is a major public health problem in India, particularly among pre-school children, and the major reason for this is the consumption of diets that do not provide adequate amounts of several nutrients. Among deficiency diseases, protein-energy malnutrition (PEM) is the most widespread, and based upon the belief then that the diets of children in whom PEM was prevalent, were deficient in protein - both in terms of quantity and quality - emphasis was laid on developing varieties of food grains that had higher-than-average protein content and a higher amount of lysine-the limiting amino acid in cereals. It was the discovery of high levels of lysine and tryptophan in the opaque 2 mutant maize, which initiated a search for similar characteristics in other foods, and subsequently varieties of cereals and millets with high protein and high lysine have been identified. When grown under apparently similar agronomic conditions in different parts of the country, they appear not to breed true. For example, when the same five varieties of sorghum were grown in two different locations - Dharwar and Indore - under the Co-ordinated Sorghum Project, those grown in Dharwar had lower amounts of protein than those grown in Indore. The extent of difference was not uniform. values were lower by 21 to 86 per cent, depending upon the variety (table 6). Values for lysine were lower in all varieties grown in Indore, a finding to be expected considering the known inverse relationship between protein and lysine concentrations . But the differences in lysine between the two locations could not all be accounted for by differences in protein alone, The concentration of leucine in the protein also showed changes from marginal to considerable.

TABLE 6. Nutrient Content of Five Sorghum Varieties Grown in Two Locations

1. D= Dharwar; I = Indore.
   Source: National Institute of Nutrition 1977.

This was also true of the nutrient content of red gram. Three varieties of red gram grown in four different locations showed that the protein content could vary by over 20 per cent without corresponding changes in either leucine or methionine, but with substantial differences in their riboflavin content. Another variety of red gram, C 11, grown in five locations, showed again that protein content could vary by over 28 per cent, the concentration of methionine by 55 per cent, and that of tryptophan by 100 per cent. Differences in the amino acid content seemed not to be related to differences in protein content (table 8).

TABLE 7. Nutrient Composition of Three Red Gram Varietiesa Grown in Four Different Locations

a. Pusa-Ageti, Mukta-R 60 and AS-3, grown under similar agronomic conditions.
Source: National Institute of Nutrition 1975.

TABLE 8. Nutrient Composition of Red Gram Variety C-11, Grown in Five Locations

Source: National Institute of Nutrition 1978.

Such locational differences do not seem to be limited to nutrient composition. They seem to apply also to the concentration of the unusual amino acid ß-oxalyl aspartic acid, present in Lathyrus sativus and believed to be the toxin responsible for neurolathyrism (table 9). They also seem to apply to the potential for supporting the in vitro production of the fungal toxin, aflatoxin (table 10).

TABLE 9. Toxin Content (ß-Oxalyl Aspartic Acid in Varieties of Lathyrus sativus Grown in Different Locations

Source: National Institute of Nutrition 1978.

TABLE 10. Locational Differences in Aflatoxin Production Potential of Maize Varieties

These findings suggest that it would not be easy to predict with any degree of confidence the nutrient composition of a variety of food grain that has a high protein potential. Apart from this practical consideration, improving protein content and protein quality was conceived as a method of improving the quality of the diet at a time when it was believed that protein was the limiting nutrient in Indian diets. This concept has now changed and the primary limiting nutrient is believed to be energy. Cereal-pulse-based diets of the type commonly eaten have a protein-energy ratio which is capable of meeting protein requirements, when consumed in amounts that satisfy energy requirements. It must be stressed that this is not to imply that there is no inadequacy of dietary protein. A fair proportion of subjects do have low protein intakes, but this is almost exclusively because total food intake is so low that both protein and energy become limiting (table 11). The relevance of efforts to improve protein quality by genetic manipulation, as a priority measure, therefore, needs re-examination, at least in the Indian context. Whether upgrading the lysine content is relevant may also be questioned, since in cereal-pulse-based diets, the first limiting amino acid is not lysine, but the sulphur-containing amino acids.

TABLE 11. Adequacy of Protein and Calorie Intake among Families in 1977

Source: National Nutrition Monitoring Bureau 1978

Turning to the availability of agricultural produces other than cereals and pulses, particularly edible oils and sugar, the situation is not an encouraging one. The per capita availability of both has gone up: that of edible oils and fats from 7.7 grams per day in 1951 to 13 in 1979, and that of sugar from 8.2 grams per day to 19.8 (table 12). Though higher now than three decades ago, these are still considerably lower than what the least-cost balanced diet recommends, which is 30 grams per capita per day (tables 13 and 14). These low availabilities are not without nutritional implications, particularly in the feeding of young children. The caloric density of cereal-pulse based diets is low - often around 1 to 1.2 calories per gram of cooked food, and a three-year-old child will have to consume over one kilogram of food to meet its energy needs. Bulk has, in fact, been known to be one of the constraints in satisfying the nutrient requirements of such children, unless the frequency of feeding is increased. A practical and easy way of increasing calorie density is to include fats and sugar - except that these two commodities are today not only in short supply, but also expensive. The recommended per capita intake of each of these food items is 30 grams per day and the effort needed to produce these quantities would be truly enormous.

TABLE 12. Per Capita Availability of Edible Oils and Sugar in India, 1951-1979

Source: Statistical Outline of India 1980.

TABLE 13. Per Capita Requirement of Food (g/day) at the National Level on the Basis of Least-cost Balanced Diets

Source: Recommended Dietary Allowances ICMR 1981.

TABLE 14. Calculation of National Food Requirements

Per capita production

= Per capita recommended dietary allowance at physiological level

x 1.1 (10 per cent kitchen and other waste)

x 1.125 (for seeds and losses)

Provided that:

Distribution is according to requirements;

There are no constraints on purchasing power.

Meeting nutritional needs

At the national level, food production appears to be sufficient to meet the country's needs (table 13). In actual practice, however, food consumption does not follow normal distribution but is skewed. A large number of families with a daily income of Rs 2 or less consume diets that do not provide enough energy, and of these, a proportion do not get enough proteins - a finding that explains the widespread PEM among young children. The primary reason for such inequitable distribution is lack of purchasing power. The impressive stocks of food grains, amounting to about 18 million tons, held in recent years, is, in fact, a reflection of this low buying power and consumption. Stocks would have been far less impressive if people could have afforded to buy what they needed. Wages and incomes have gone up over the years but they do not seem to have kept pace with the rising costs of even essential food commodities. Data collected by the National Nutrition Monitoring Bureau show that food consumption has not changed significantly over the last few years.

Due to increased agricultural production in the country, food-grain imports have progressively come down and, during recent years, have all but stopped. The agricultural situation has also been able to prevent the serious widespread famines that used to occur in earlier years. Both are no mean achievements. But increased production seems to have made little impact on the widespread chronic malnutrition in the country, with all its health and developmental implications. The mean birth weight of infants born to mothers belonging to poor rural groups, which was 2.7 kg in 1951, has remained so even today. The proportional mortality rate whereby one-third of all deaths in the country in 1951 occurred among children below the age of five years, continues to be as high even today. Severe forms of protein-energy malnutrition such as kwashiorkor and marasmus were seen in 3 to 5 per cent of children of pre-school age three decades ago. Prevalence rates are not different now (table 15). Limited data available on mean body weight and height of adults show little improvement. There are, therefore, no indications that malnutrition has been contained in any way, despite improved food production.

TABLE 15, Nutritional Status of Pre-school Children

Source: National Nutrition Monitoring Bureau 1977.

Should it be possible to achieve a more equitable consumption of food in the coming years, the level of production, which apparently looks adequate at present, would cease to be so, for two main reasons. Buffer stocks can no longer be maintained at satisfactory levels. Also, children who from birth get enough food, would be able to fully express their genetic potential for growth and become bigger toddlers, bigger adolescents, and bigger adults, with clearly bigger food needs. The level of production would have to increase at a rate faster than that which the country has been able to achieve in the immediate past.

Increased agricultural production is a key factor in ensuring adequate food supplies. The agricultural policy of a country will have to take care of the relevant aspects of its nutrition policy, if the food needs of the population have to be met. Imbalances in production of different commodities have to be corrected and more importantly food has to be made available at a cost that the great majority can afford. Until such time, adequacy of agricultural production will be more apparent than real. It must not be forgotten that factors outside agriculture also have a role in influencing nutrition.

References

Gopalan, C., and B.S. Narasinga Rao. 1968. Dietary Allowances for Indians. Special Report Series No. 60, Indian Council of Medical Research, New Delhi.

ICMR. 1981. Recommended Dietary Intakes for Indians. Indian Council of Medical Research, New Delhi.

National Institute of Nutrition. 1975. Annual Report. Indian Council of Medical Research, Hyderabad.

_. 1977. Annual Report. Indian Council of Medical Research, Hyderabad.

_. 1978. Annual Report. Indian Council of Medical Research, Hyderabad.

National Nutrition Monitoring Bureau. 1977-1978. Annual Reports. National Institute of Nutrition, Hyderabad.

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