The news release from the Office of Dietary Supplements at the National Institutes of Health was titled “Will Supplements Help Your Workout or Diet Routine?” The release links to two separate sets of documents, one on weight loss and one on sports performance, on the National Institutes of Health website.
The two parallel documents summarize, both for consumers and in more detailed fashion for health professionals, the research backing for a number of popular ingredients in both categories. The overarching takeaway is that in the opinion of ODS, there is little compelling evidence for the efficacy for many of the ingredients in either group.
Efficacy rarely on agency's radar
The US Food and Drug Administration, while charged with regulating dietary supplements, has as a rule not weighed in much on the efficacy side of the coin for dietary supplements and their ingredients. DSHEA, the overarching regulation that created the modern dietary supplement category, includes boilerplate language that states the claims made on supplements have not been evaluated by FDA. A few qualified health claims have been approved in the more than two decades since DSHEA was enacted, but as a rule companies have found the language of these to be so restrictive and doubt-inducing as to be more or less useless from a marketing perspective. As a result, these approved claims rarely if ever appear on packaging.
That hasn’t stopped marketers from claiming certain effects for their products. Products can claim to support the structure or function of certain tissues or processes in the body. And over the years marketers have found ways of pushing the envelope on what a structure/function claim looks like.
In the NIH-resident documents, ODS gives a detailed view of how it has evaluated the science behind these ingredients. Some of the common sports ingredients evaluated are beet root juice, beta alanine, creatine and protein; among weight loss ingredients caffeine, green coffee bean extract, green tea extracts and probiotics were evaluated.
All told, the charts included 24 weight loss ingredients and 21 sports performance ingredients. The evaluations found little to no evidence backing the claimed effects for 12 of the 21 sports ingredients. The weight loss ingredients fared similarly with ODS concluding that 14 of the 24 ingredients had either minimal effects or none whatever.
“Dietary supplements marketed for exercise and athletic performance can’t take the place of a healthy diet, but some might have value for certain types of activity,” said Paul M. Coates, PhD, director of ODS. “Others don’t seem to work.”
“Americans spend over $2 billion a year on dietary supplements promoted for weight loss, but there’s little evidence they actually work,” said Anne L. Thurn, PhD, director of the ODS Communications Program.
Hector Lopez, MD, has experience conducting clinical trials through his position as a principal at the Center for Applied Health Sciences, a contract research organization, and in popularizing the results of those trials via his involvement with the International Society of Sports Nutrition. Dr Lopez said that ODS has applied strict criteria similar to what the Cochrane Collaboration uses for evaluating the clinical trials conducted on the ingredients. To some degree, these restrictive criteria speak to the ongoing controversy about what the best mode of research for nutritional products might be.
Randomized, controlled trials on dietary supplement ingredients will always seem to pale in comparison to pharmaceutical-style multi center trials because dietary supplement ingredient developers cannot afford studies with hundreds or thousands of subjects.
“It appears ODS is using very conservative criteria akin to those used by the Cochrane Collaboration or in the evidence-based medicine movement of systematic reviews. These criteria tend raise the bar necessary to reach conclusive evidence of efficacy, and relate to creating overarching recommendations for large population groups, but can be quite limiting for the individual consumer,” Dr Lopez told NutraIngredients-USA.
“Many of these ingredients require assessing the totality of the evidence with much more context in order to make the best decision on whether potential benefits outweigh the potential risks. In the case of dietary supplements for exercise and athletic performance, you have to take into account the individual dietary and lifestyle needs, nutrigenetics, specific sport or mode of exercise, training volume, intensity, frequency, and so forth,” he said.
“The good news here is that ODS concluded that for the most part the evidence of the safety of these ingredients was substantial, and the subsequent text that followed the tables in the fact sheets provided a relatively thorough analysis of some of the nuances of the data supporting the use of these ingredients” Dr Lopez added. He has insight into the safety side of the supplement coin via the other hat he wears, as co founder of adverse events contractor Supplement Safety Solutions.
Varying quality of trials hurts industry
Larisa Pavlick, vice president of global regulatory and compliance with the United Natural Products Alliance, said having an evaluation like this—and a peek into the agency’s thinking—all in one place will be a service to both consumers and industry.
“I think they did a good job with these pages,” Pavlick said.
One issue that the evaluations raise is the varying quality of studies done on these ingredients. Research on dietary supplement ingredients appears to be getting better over time, with ingredients more carefully characterized and better study designs being used.
Still, the ODS observed that for a number of these ingredients, the available trials were of “poor” or “varying methodological quality.” That’s on industry, she said.
“There is guidance out there for how to design a clinical trial, and I think we do have to respect that those guidances are there. It does look great when you have larger populations, but that’s not the reality in the supplement world. But I think as long as those trials are designed by following the guidances for evidence, they will be respected,” Pavlick said.