WASHINGTON, D.C., May 7, 2007 —At a May 3 scientific symposium, The Workshop, presented by the Council for Responsible Nutrition (CRN), the trade association’s President and CEO Steve Mister challenged the audience of scientists to consider whether the drug model for scientific research—relying strictly on randomized clinical trials (RCTs) and evidence-based medicine (EBM)—is the most appropriate research model for nutrients, including dietary supplements.
“We recognize the scientific rigor of RCTs, and they are certainly an important piece of the research puzzle,” said Mr. Mister in his opening remarks at The Workshop. “But we cannot ignore all the other research—case-control and cohort studies, and other epidemiological data—as these studies often point us in the direction indicating where further research should be focused and may be just as rigorous for proving hypotheses as well as developing them. If observational studies show a benefit which is not confirmed by a clinical trial, that does not discount the importance of the initial studies. The totality of the evidence should not be dismissed.”
Mr. Mister’s comments echo what some experts in the field of nutrition research have been thinking.
Speaking last week at SupplySide East, a trade show widely attended by dietary supplement industry executives, Jeffrey Blumberg, Ph.D., a professor in the Friedman School of Nutrition Science and Policy at Tufts University, said, “As with each research approach, there are inherent limitations to the use of RCTs, particularly when testing the effectiveness of preventive nutrition. In contrast to drugs, nutrients have beneficial effects on multiple body tissues and interact in a dynamic fashion with other nutrients found in supplements and the diet. But most RCTs can test only one or two compounds, each at a single dose, for a few years—too short a period to have significant impact on chronic diseases that take decades to develop.” Dr. Blumberg further pointed out that RCTs must test a very specific and narrow question under a particular set of conditions, making it difficult to extrapolate the results to the general population. “Thus,” he concluded, “diet and nutrition recommendations must rely on the totality of available evidence rather than exclusively on a single research approach like the RCT.”
Looking at the full spectrum of research available, including observational studies, can provide a clearer picture of the benefits of supplements. Observational studies can often better represent typical populations. These studies have a closer relationship to how foods and supplements are used in the “real world” than a clinical setting would offer. Additionally, observational studies are often the only feasible or ethical approach in cases where eliminating essential nutrients as part of the RCT study design could be detrimental for the study population.
Robert P. Heaney, M.D., of Creighton University’s Osteoporosis Research Center, and a speaker at The Workshop, agreed, “Healthcare professionals and regulatory agencies looking for ways to evaluate health claims have eagerly embraced an evidence-based medicine approach without checking to see if it fits the nutrition context.” According to Dr. Heaney, it does not. He explained that EBM ranks RCTs highest among different research methods for studying efficacy; however, RCTs are typically limited in their relevance to the general population and may impose many constraints that are ill-suited to testing nutrients, including vitamins.
Two major examples of how well-established bodies used observational studies in developing nutritional guidelines include: the Institute of Medicine’s (IOM) Dietary Reference Intakes
(DRIs) and the U.S. Department of Agriculture’s (USDA) Dietary Guidelines for Americans. IOM noted, “The scientific data used to develop DRIs have come from observational and experimental studies.” USDA said of the development of its Dietary Guidelines, “The primary types of studies used were observational and clinical trials. Specific types of observational studies were cross-sectional studies, case-control studies, and cohort studies.”
Mr. Mister also pointed out a catch-22 for the supplement industry. In addition to the problems associated with using RCTs for studying nutrients, using RCTs to study prevention may be neither practical, affordable or in some cases even appropriate. Further, RCTs are generally based on treatment modalities. But dietary supplements, by law, are prohibited from using treatment claims on their products; therefore, there is even less incentive for companies to fund treatment-oriented RCTs.
“The research community needs to re-evaluate how to most efficiently and productively conduct nutrition research,” Mr. Mister observed. “Members of industry and other stakeholders need to support scientific research in all of its valid forms in order to further the broadest and best knowledge about how dietary supplements can help people live healthier lives.”
The Council for Responsible Nutrition (CRN), founded in 1973, is a Washington, D.C.-based trade association representing dietary supplement industry ingredient suppliers and manufacturers. CRN members adhere to a strong code of ethics, comply with dosage limits and manufacture dietary supplements to high quality standards under good manufacturing practices.