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LETTER TO THE EDITOR |
Department of Nutritional Sciences
University of Wisconsin–Madison
Madison, WI 53706
E-mail: sherry{at}nutrisci.wisc.edu
Dear Sir:
In theory, Dr Penniston and I agree with the sentiments of Dr Prakash regarding the potential, serious implications of vitamin A supplementation programs (1). In an ideal world, all people would get the nutrients they need from the foods they eat. However, mostly because of poverty, this ideal does not exist. Vitamin A supplementation programs began in the 1970s as a way to prevent xerophthalmia in preschool children. They were meant to be a temporary initiative until more sustainable approaches could be put in place. Three decades later, developing countries with scarce resources for such public health programs are questioning the supplementation programs, and yet other initiatives, eg, fortification of common foods or biofortification of staple crops, are not yet universally in place.
Our purpose in writing our recent review was not to diminish the importance of vitamin A supplementation programs, as has been described elsewhere (2). In fact, mathematical estimations have dismissed the potential for toxicity in the general audience that receives these supplements (3). We would, nonetheless, like to reiterate that maternal dosing regimens have not been carefully evaluated. In our work in the lactating sow, the higher dose (equivalent to 400 000 IU), given in one bolus, did elicit a greater detoxifying response (4) than the lower dose (equivalent to 200 000 IU), without any added benefit to the offspring (5, 6). Several investigators have given the 400 000-IU dose to lactating women in research settings (7, 8), which we hope does not become common practice. Further research in women and on the benefit to their nursing infants is necessary to fully endorse supplementation programs aimed at lactating women at the community level.
We also agree with Prakash that health policy managers should not dismiss the value of nutrition education programs to promote dietary diversification. Vegetables in general have been given "bad press" with respect to their vitamin A value (2, 9). However, recent studies clearly show that serum retinol concentrations are lower with vegetable feeding than with supplement or liver feeding, but all treatments, including vegetables such as carrots and green leaves, reduced the incidence of night blindness (10).
What is the best way for people to get vitamin A? Biofortification of stable crops with ß-carotene is certainly one way that can be sustainable, but it also requires a huge nutrition education effort for people to change from "white" varieties of foods—particularly in the case of maize, potatoes, and rice—to "orange" varieties of foods. Efforts in the United States to simply increase fruit and vegetable consumption are still required, although research clearly shows the health benefits. Therefore, we ask: can one assume that all educational efforts to increase the consumption of colored staple crops or vegetables would be successful?
As developing countries are considering alternatives to vitamin A supplementation programs, the potential for toxicity should be kept in mind. For example, do young children need high-dose supplements, "sprinkles" on their cereal, and preformed vitamin A in sugar, noodles, and cooking oil? Each country should consider the programs that are in place and set up appropriate evaluation programs so that segments of the population that may be exposed to more than one initiative can be monitored.
The ideal would be that all people would eat 4.5 cups (ie, 1.1 L) of various fruit and vegetables each day as recommended by the 2005Dietary Guidelines for Americans (11) as part of a 2000-calorie diet. With that intake, no one would have vitamin A deficiency, and the added health benefits of a lower incidence of chronic disease would redound to all. However, the ideal does not exist, and, therefore, vitamin A supplementation programs will remain in place until the ideal or alternative programs do exist.
ACKNOWLEDGMENTS
The author had no personal or financial conflict of interest.
REFERENCES
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