Journal or Publishing Institution: Journal of the Academy of Nutrition and Dietetics
Study: https://search.proquest.com/docview/218449370?pq-origsite=gscholar
Author(s): Nestle, M. and Greger, J.L.
Article Type: Journal Publication
Record ID: 1719
To the editors: The suggestion that “golden” rice, bioengineered to contain Beta-carotene (1), could have a “real impact on the health of children living in Southeast Asia” (2) deserves critical scrutiny from nutrition professionals. This rice, although not yet available commercially, has become the “poster child” of the food biotechnology industry’s extensive public relations campaign to convince the public that the benefits of genetically engineered agricultural products outweigh any safety, environmental, or social risks they might pose. (3) National magazines promote golden rice as a means to prevent the more than one million annual deaths and cases of blindness that occur among children in developing countries as a result of vitamin A deficiency. (4) The creation of golden rice appears to confirm the belief that biotechnology is the key to solving world food and nutrition problems. (5)
Consideration of basic principles of nutrition suggests that rice containing Betacarotene is unlikely to alleviate vitamin A deficiency. To begin with, the bioavailability Beta-carotene is quite low10% or less by some estimates. To be active, Beta-carotene-a provitamin-must be split by an enzyme in the intestinal mucosa or liver into two molecules of vitamin A. Like vitamin A, the provitamin is fat soluble and requires dietary fat for absorption. Thus, digestion, absorption, and transport of Beta-carotene require a functional digestive tract, adequate protein and fat stores, and adequate energy, protein, and fat in the diet. (6) Many children exhibiting symptoms of vitamin A deficiency, however, suffer from generalized protein-energy malnutrition and intestinal infections that interfere with the absorption of Beta-carotene or its conversion to vitamin A. (7) In numerous countries where vitamin A deficiency is endemic, food sources or Betacarotene are plentiful but are believed inappropriate for young children, are not cooked sufficiently to be digestible, or are not accompanied by enough dietary fat to permit absorption. (8) In addition to doubts about cost and acceptability (2), biological, cultural, and dietary factors act as barriers to the use of Beta-carotene, which explains why injections or supplements of preformed vitamin A are preferred as interventions (8). The extent to which the Beta-carotene in golden rice can compensate for these barriers is limited. Vitamin A deficiency is undeniably the single most important cause of blindness among children in developing countries and a substantial contributor to illness and death from infectious diseases (9). Mortality rates are higher among children with even mild vitamin A deficiency, but fall by as much as 54% when vitamin A-not Beta-carotene-is supplemented or injected (8). Because such intervention methods are expensive and difficult to accomplish in the field, and because so many children exhibit signs of generalized protein-energy malnutrition, food-based approaches to improving vitamin A status seem especially desirable (10). The addition of one or two nutrients to an existing food does not constitute a food-based approach.
Furthermore, the use of Beta-carotene as a single-nutrient supplement itself raises questions. Although fruits and vegetables containing Beta-carotene are demonstrably protective against disease (11), the resuits of clinical trials of Beta-carotene supplements as a means to prevent cancer or cardiovascular disease have proved disappointing (12,13). Some laboratory studies support the idea that Beta-carotene produces biological effects that might protect against cancer (14), but others suggest that it might be co-carcinogenic (15). Still others argue that Beta-carotene is a pro-oxidant that may be harmful or beneficial, depending on circumstances (16). What all this means is that the short- and long-term effects of supplementation of Beta-carotene as a single nutrient-distinct from the foods that contain it-are as yet uncertain.
The complexity of the physiological, nutritional, and cultural factors that affect vitamin A status suggest that no single nutrient added to food can be effective as a remedy for dietary deficiencies. Instead, a combination of supplementation, fortification, and dietary approaches is likely to be needed (17), along with a substantial commitment to improve socioeconomic status. Food biotechnology may yet lead to products that improve nutrition and health, but at the moment its benefits remain theoretical.
Keywords: Golden Rice, Bio-engineered, Health Impact, Nutrition, Vitamin A Deficiency, Beta-carotene, Food Biotechnology
Citation: Nestle, M. and Greger, J.L., 2001. Genetically engineered” golden” rice unlikely to overcome vitamin A deficiency/Response. Journal of the Academy of Nutrition and Dietetics, 101(3), p.289.
