It is these subpopulations that NIH expects Davis to study. The Davis center’s grant comes from NIH’s National Center for Minority Health and Health Disparities. Already researchers have found that African-American and Mexican women exhibit differences in folate metabolism, which can affect cancer risk and has been implicated in neural-tube defects in newborns. Green leafy vegetables are rich in folates. But if a diet recommendation is to be realistic or helpful, it must take into account what people can afford and whether they can find it. And that’s to say nothing of whether they like eating, say, broccoli (the cure-all, along with its cruciferous cousins cauliflower and cabbage) and soy, which many non-Asians view with dread.
Rodriguez is excited about preliminary results involving soy and prostate cancer, to which African-American men are disproportionately susceptible. In 1997, a researcher at the University of California, Berkeley, Alfredo Galvez, studied the benefits of lunasin, a bioactive isoflavone in soy apparently associated with reduced levels of heart disease and several cancers, including prostate. Lunasin seems to increase the expression of genes that monitor DNA damage and suppress tumor cell proliferation.
These results – like so many that the public and the food industry seize on – are based on cell cultures, not human studies. So Kevin Dawson, senior informatics scientist at the Davis center, initiated a collaboration with the Prostate Cancer Education Council in Colorado, where rates of prostate cancer are high and where data collection is both broad and detailed. The results seem so promising that they should encourage everyone to eat soy protein once a day (unappetizing as that might sound). But Dawson cautions that the picture of prostate cancer he is trying to draw involves many more nutrients, and that the effects of soy in different populations – especially in populations that have not traditionally included soy in their diets – must be studied over the long term.
For now, even Rodriguez is disposed to generalize his diet recommendations. For example, he recently told a man who has sought alternative treatments for his late-stage prostate cancer to eat tomatoes and sauces with tomato paste for their lycopene, which is strongly associated with lowered incidence of prostate cancer, and to try to eat soy, too, in soy milk or edamame.
Anxious yuppies want more sooner, of course, not to mention eternal, aging-free life. Companies offering “DNA diets” promise customized, expensive diets that fit right in with the current idea of personal service as status symbol. It hardly matters, perhaps, that the number of genes such companies are able to test for is minuscule, and that the advice they can give will almost certainly not be a matter of life and death. Their selection of genes is based on published papers, their nutritional guidance usually the latest from the American Heart Association. What matters is that the idea is catching on, in a very small and very health-conscious segment of the population – and that the commonsense advice the companies are likely to give, with the smallest soupçon of genetic-based rationale, is unlikely to do any harm.
Rodriguez does see home testing in the future: “The trend is faster better cheaper, for private, in-home, disposable tests. Pee on a stick and see if I’m at risk for many diseases.” And optimists say that in ten years the number of genes that can be reliably and cheaply tested for will be closer to 1,000 than 20, and that patients will arrive at health providers’ offices carrying their own gene chips, which can be fed into computers.
If the American Dietetic Association has its way, those health providers will be dieticians. Last April, the journal of the 65,000-member group published a review of nutritional genomics that concluded that the “limited number of certified genetic counselors” left the field clear for “dietetics professionals…to play a primary role.” Dieticians as counselors is fine by Rodriguez, who says that doctors want the kind of yes/no, disease/not disease binary conclusions that nutritional genomics can’t yet provide, and that dieticians know something about preparing food, whereas nutritionists concentrate on research. That dieticians know much about preparing food is a debatable point, at least for food writers, but they often do take a concerned interest in your welfare.