Connie Weaver, a Purdue University nutritionist and director of that institution's Botanicals Research Center for Age Related Diseases, first became interested in soy isoflavones in 1999. I went to a local health food store, she recalls, and there were 13 different supplements that claimed to be effective for bone loss. But when she checked the research, Weaver recalls, the literature was pathetic. I decided we'd better start doing some studies.
What she and other researchers have found is a vast swamp of complexity. Of the two main isoflavones, genistein and diadzein, the former seems to be more effective in preventing osteoporosis. Unless, that is, the person consuming it happens to have bacteria in the gut that convert the compound diadzein into another one called equol, which might offer more bone protection than either of the soy isoflavones--or might not. And there's even some worry that the soy compounds could boost rates of breast cancer, just as estrogen supplements used in hormone replacement therapy can.
Nutritionally you've got to appreciate soy, Weaver says, but there are also all these bioactive substances in there. At high concentrations, she adds, the problem is that they do some good things, some other things, and some who-knows-what things. The goal, Weaver asserts, is to figure out what combinations have advantageous impacts on bone health, heart health, and so on, without deleterious impacts. At least three long-term trials testing the effects of soy isoflavones on bone health are in progress, Weaver notes, but we've got a long way to go before we can say what works and what doesn't.
That conclusion means more research, of course, and dozens of nutraceutical trials are under way, many sponsored by ODS and other branches of the NIH. But some investigators fret that vital studies are being rushed or overlooked because of limited research funding. Peters worries that lycopene's lackluster performance to date may mean that it never progresses to clinical trials--a situation that could leave millions of consumers paying for supplements that might not be doing them any good. We can't recommend using lycopene based on the current evidence, Peters says, but that doesn't mean it has no benefit. There are some important studies that haven't yet been done.
Similarly, Greg M. Cole, a researcher at the University of California, Los Angeles, who sees great promise in using omega-3 fatty acids to prevent Alzheimer's disease and other forms of age-related dementia, expresses concern that current clinical trials lack funding to target the most promising patient population--people who have not yet started to show signs of those problems. The risk of Alzheimer's doubles with every five years after age 65, he says, and we've got a generation of 75 million people heading into that. We can't afford to miss something that might help with prevention just because we couldn't find the money to study it.
In the meantime, patients, physicians and just plain folks will have to do the best they can to make smart choices with incomplete and potentially misleading information. The oversight of dietary supplements is loose: FDA regulations allow for several different types of efficacy claims to be made on labels, including fairly robust significant scientific agreement claims that the nutrient in question has a direct effect on a specific disease, but also so-called qualified health claims, where phrases such as some evidence suggests that are added. There's even room for structure/function claims: calcium builds strong bones is a noncontroversial example--which are not even evaluated by the FDA. (The claims do have to carry a footnoted disclaimer to that effect, however, a stipulation that can result in supplement labels with more asterisks than a Major League Baseball record book.)
The danger of pseudoscience and quackery is very real, says Jeffrey I. Mechanick, an endocrinologist at the Mount Sinai School of Medicine who has written extensively about the use of dietary supplements in the treatment of diabetes and other metabolic diseases. Dietary supplements in general should not be supplanting proven therapies, he cautions, but I don't see any reason to use words like alternative or complementary to describe them. I just use proven or unproven, and that proof is what should guide patients and their physicians.