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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...