Beyond the domain of averting frank deficiencies, the effect of any given nutrient is largely determined by individual factors, such as how well someone digests and absorbs the nutrients, what nutrient-depleting or nutrient-blocking drugs are in a person's system, and individual capacities to metabolize particular nutrients, Dr. Bland continued. Nutrition is definitely not a one-size-fits-all proposition, he stressed.
High-profile government-funded studies understandably carry a lot of weight with physicians, said Dr. Mary Hardy, medical director of the Center for Integrative Oncology at the University of California, Los Angeles. But all too often, “we just run with the top-line findings, and miss secondary but important signals.” Although the SELECT study did not show the hoped-for prostate protective benefit, it did show there were no major selenium-associated adverse effects after 6 years' of continuous use, she pointed out, which is reassuring for anyone taking this mineral for other purposes.
Currently, the ODS is working with the federal Agency for Healthcare Research and Quality (AHRQ) and AHRQ's Evidence-Based Practice Centers to conduct a series of meta-analyses and systematic reviews, Dr. Coates said. Of the role of the ODS, Dr. Coates said, “We set the questions, and then we walk away. The Evidence-Based Practice Centers do the actual reviews.”
Future reviews will look at chromium and insulin sensitivity; omega-3s for cardiovascular disease prevention; the effects of soy, B vitamins, and antioxidant phytochemicals on neurodegenerative diseases; and the health effects of vitamin D. Some of these reviews were mandated by Congress. Completed reports can be found at www.ahrq.gov/clinic/epcindex.htm
Negative studies are a fact of life in science, he added. Although it may seem like supplements are being treated unfairly, the reality is that a lot of pharmaceutical studies are negative, too.
“Most things don't work all the time. In the case of St. John's wort, there was a study a few years ago showing that it doesn't work well in mild to moderate depression. That simply puts it in the company of most antidepressant drugs, which don't work 50% of the time.”
The recent vitamin E/C combination trial had its roots in population studies.
Source James E. Reinaker/Elsevier Global Medical News