When Is a Supplement Safe and Effective?
You’re a hip health nut, right?
Perhaps you’re taking vitamin E to help prevent heart disease.
Maybe some folic acid supplements to keep the old ticker healthy.
And, possibly, you pop a selenium supplement each day to lower your cancer risk.
After all, widely publicized scientific evidence shows that each of these vitamins or minerals has an effect on preventing or treating disease. The problem is that, many health experts say, not enough evidence exists at this moment to warrant consumers’ use of these substances for the treatment or prevention of disease.
Yes, the evidence for a positive health effect is good--just not good enough to support a public policy recommendation for use.
Just how much evidence is needed for consumers to feel confident that a nutritional supplement is safe and effective? That is the profoundly complex question that scientists, government regulatory officials and nutrition-supplement manufacturers are wrestling with as interest in the health effects of vitamins, minerals and herbs soars.
At present, the U.S. Food and Drug Administration allows health claims to be made regarding only a few supplements: calcium for its role in helping prevent osteoporosis and folic acid for its effect on helping to prevent birth defects of the spinal cord.
But as public and professional interest in supplements grows (there’s even a new term for foods or nutritional supplements that carry medical-health benefits--”nutraceutical”) there is increasing pressure on manufacturers and health officials to quickly clarify the value of a given supplement that is already making headlines.
This struggle was at the heart of the annual conference of the Council for Responsible Nutrition, a supplement-manufacturers’ trade organization, last week in Dana Point.
“Our industry is more visible than ever before,” said John Cordero, president and chief executive officer of CRN. “This brings an unprecedented level of public trust. Consumers demand to know that our products work.”
According to Cordero, the majority of supplement manufacturers is eager to see scientists declare the medicinal value of their wares. Supplement manufacturers are permitted by law to make “nutrition support statements” regarding their products. These statements can address modest facts, such as how the supplement functions in the body, says Annette Dickinson, director of scientific and regulatory affairs for CRN.
The vast majority of nutritional supplement products carry such statements.
In contrast, health claims are much weightier statements regarding the effects of a nutrient on the treatment or prevention of a disease. These claims must be authorized by government regulators and frequently become public policy recommendations, such as the government’s backing of folic acid supplementation to prevent birth defects.
The use of vitamin E and folic acid for the prevention of heart disease and selenium for cancer risk reduction are considered to be front-runners in the race to receive health-claim status. But, in each case, there is still disagreement on whether more scientific evidence is needed.
Dr. Robert Russell, a Tufts University nutrition researcher, says a particular type of scientific study should be completed before any public policy recommendations are made: a randomized, controlled intervention trial in which a group of subjects receives the nutrient while a similar group receives a placebo. The two groups are followed for a length of time and are compared.
This “gold standard” study should precede any health claims regarding the effects of nutrition supplements on disease, he said at the CRN forum.
“Before advocating supplements, there should be reproducible intervention trials showing positive results,” Russell said. Without those studies, he said, problems of toxicity or interference with other nutrients might not be discovered.
Americans are too quick to begin taking supplements before the total health impact is clear, agreed Dr. Stephen T. Sinatra, a cardiologist at the New England Heart Center. For example, some men taking a multivitamin with a high iron content may be at risk for a dangerous condition called iron overload.
“The truth is that you can do harm. The public has to be aware of these things,” Sinatra said. “Also, too much of one nutrient can wash out other nutrients.”
Sinatra, however, recommends many supplements to his patients despite the lack of controlled intervention trials. He bases his recommendations on preliminary scientific evidence demonstrating a positive effect as well as blood tests to monitor his patients.
“The problem is, there is a lot of basic science about supplements that is not getting [disseminated],” he says. “There are a lot of physicians who are biased [against using supplements] unless large, random intervention trials have been done.”
Other health experts also bemoan the high standards that must be met before a supplement can be recommended to the public.
“These [intervention trials] are expensive and long-term. We’d like to think they are quick and no problem,” says William A. Pryor, a biochemist at Louisiana State University. “I believe it should be possible to continue to fine-tune your recommendations as more evidence becomes available. Intervention trials are the gold standard, but sometimes we just shouldn’t wait. And people don’t want to wait. We should do the studies but make what recommendations we can in the meanwhile.”
