Can Golden rice eradicate vitamin A deficiency?

VARIOUS KINDS of transgenic rice are being developed for a range of characteristics.

These are developed to be used both as food as well as for industrial purposes. Among these, nutritional enrichment has been receiving considerable attention especially in India.

Among all the transgenic crops, transgenic rice is claimed to provide maximum benefit to the consumer while other crops provide benefit mostly to the producer. .

Nutritional Genomics has been applied to rice for the development of Golden rice, iron enhanced rice and rice with enhanced proteins and amino acid. The proponents of Golden rice claim that its consumption provides the required vitamin A dose to prevent nutritional blindness in populations where xerophthalmia is endemic.

Although the initial experiments with Golden rice appear to indicate potential for alleviating vitamin A malnutrition, there is a need to examine in depth several factors before accepting this technology as an intervention strategy.

The total dietary exposure and exposure to the modified nutrient among various age groups, especially the vulnerable segment of the population need to be considered.

An adult would have to eat 3.7 kg (equivalent to about 9 kg of cooked rice) to obtain the total daily requirement of vitamin A. The projected serving size of 300 gm is claimed to provide only 8 per cent of the daily requirement. On the other hand, the developers of the transgenic crop dispute the calculation and suggest that only 0.75-1.5 kg rice would have to be consumed to meet the recommended daily allowance (RDA) and rice can provide 20-40 per cent of the RDA from a 300 g serving.

Since rice is a staple food in large parts of the country and vitamin A deficiency is still a problem of public health significance, specially among children, it is essential to look into the Indian scenario.

The surveys of the National Nutrition Monitoring Bureau indicate that the average cereal intake is 106 gm per day among 1-3 year old children. As per the ICMR Expert Committee, RDA for age groups 1-3 years of retinol equivalents in India is 400 microgram per day while for betacarotene it is1600 microgram per day.

The current dietary intake of betacarotene among these children is estimated to be 788 microgram per day. Golden rice would provide an additional intake of betacarotene of 186 microgram per day. Thus, while from the current diet 49 per cent of RDA of betacarotene is met and from golden rice an additional 12 per cent, the total from both sources would be 61 per cent.

However, Dr.Peter Beyer of the University of Freiberg, Germany, who along with Dr.Ingo Potrykus is the developer of the Golden rice, claimed that "whatever quantity they eat would be sufficient to keep blindness and other problems at bay" (The Hindu, 7 Nov, 2002). Based on the above data, obviously such a claim appears to be not correct.

Another important fact that has to be considered in this context is the bioavailability of betacarotene in the Indian context. The bioavailability of betacarotene is low compared to vitamin A and it depends on various dietary factors like level of protein and fat in the diet, protein and fat stores and cooking and processing methods.

Protein Energy Malnutrition and intestinal infections and infestations affect the absorption of vitamin A among children. Moreover, an intake of at least 5gm fat is necessary for betacarotene absorption. The consumption of fat among the needy communities is woefully inadequate.

An evaluation of bioavailability of betacarotene from Golden rice requires to be urgently assessed before any conclusions about the actual potential of Golden rice to meet its requirements are drawn.

There is no information as yet on consistency of the level of betacarotene production in Golden rice, particularly with respect to the nutrient amounts as claimed, when it is grown in different environmental conditions, in different locations under different levels of fertilizer application and management. What is more important is the acceptability of yellow Golden rice that requires further investigation.

Thus, many questions are yet to be answered and we have miles to go before Golden rice can be claimed to help eradicate the problem of vitamin A deficiency in the country.

Ramesh V. Bhat and S.Vasanthi

National Institute of Nutrition Hyderabad

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