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Evidence- Based Nutrition Science?

Friday, June 14, 2013


Scientists have been asked for years to consider whether the drug model for research relying strictly on randomized clinical trials (RCTs) is actually the most appropriate evidence-based research model for nutrients, including dietary supplements. 

The recently released results of the AREDS2 study suggest this question is reasonable. 

All scientists recognize RCTs because they are such an important piece of the drug research puzzle, but we cannot ignore all the other research; case-control and cohort studies, and other epidemiological data, as these studies often indicate where further research should be focused and they may prove or disprove hypotheses as well as develop them. 

Steve Mister, the president of the Council for Responsible Nutrition challenged a group of scientists in a Washington, D.C. symposium a couple of years ago with this comment, "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."

In an article published in Nutrition Review, Jeffery Blumberg, PhD, professor in the Friedman School of Nutrition Science and Policy at Tufts University suggested that 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 in the diet. But most RCTs only test a few nutrients on complicated  degenerative disease that takes 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 diet and nutrition recommendations must rely on the totality of available evidence rather than exclusively on a single research approach like the RCT.

It’s important that science look at the full-spectrum of micronutrient research and evidence available, including observational studies because it 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 in a clinical setting. 

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 to the study population. 

The Institute of Medicine's (IOM) Dietary Reference Intakes (DRIs) include observational studies when developing nutritional guidelines and safe upper limits of micronutrients. 


Ellen Troyer, MT MA -
Biosyntrx CEO / Chief Research Officer


PEARL

Nutrition research is in a catch-22. In addition to the problems associated with using RCTs for studying nutrients, using RCTs to study prevention may be neither practical, affordable or in most cases even appropriate.  RCTs are generally based on treatment modalities. But dietary supplements, by FDA law, are prohibited from using any type of treatment claim on their products no matter if there is vast amounts of supporting science; therefore the incentive is limited for companies to fund therapy-oriented RCTs. 










References

Evidence-based criteria in the nutritional context. Blumberg J, Heaney PR. et al. Nutr Rev. 2010 Aug,68(8):478-84 [abstract]