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Speaker: Supplements should be vetted differently than pharmaceuticals
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NEW YORK – “Randomized clinical trials are very good for testing drugs, but when we’re talking about individual foods or patterns, the way these studies are conducted are not a gold standard,” Jeffrey Blumberg, PhD, said here at the Ocular Nutrition Society symposium, held during Vision Expo East.
“With a randomized clinical trial (RCT) you have a nonexposed or placebo group,” Blumberg said. “This doesn’t work for a nutrient trial. Your participants have probably eaten before you’ve seen them. You can theoretically introduce a nutrient deficiency, but that’s unethical.”
Another issue with testing nutrients vs. drugs is that drugs principally target a single system, while nutrients are “pansystemic in their effect,” he said
Drug studies look for a large and targeted effect, Blumberg said. However, “nutrients don’t work that way. Their effects are usually modest, but aggregated across multiple systems over long periods of time.”
For example, with a negative calcium balance of 30 mg/d, an individual will lose 10% of his or her bone density mass per year and have osteoporosis in 30 years, he said.
A challenge in designing a RCT for a nutrient is deciding what different outcomes you will be looking at to tease out the one you need, Blumberg said.
“Different conditions require different levels of nutrients,” he said. “What is the right dose for the outcome you’re interested in?
“You must look at intake or baseline status before you provide the intervention,” he continued. “It’s like doing a clinical trial with a new antihypertensive drug and not measuring blood pressure at baseline.”
Blumberg said a study of nutrients must consider the health status of the people in the study, their lifestyle, their baseline nutrient intake and status, and their susceptibility to the outcome.
Absorption is also an issue, he said.
“Patients may have taken the supplement, but was it absorbed properly?” he asked.
The U.S. Food and Drug Administration has proposed a new guidance for requiring investigational new drug applications for human studies of supplements when they are intended to prevent “damage to an organ, part, structure or system of the body such that it does not function properly (e.g. cardiovascular disease) or a state of health leading to such dysfunctioning (e.g. hypertension).”
“This is treating nutrients exactly like drugs,” Blumberg said. “If it comes forth, it’s going to inhibit a lot of nutrition human intervention studies. It will be too hard to do these studies in the U.S.
“I’m not suggesting the standard of proof should be lowered,” he noted. ‘I’m saying that requiring an RCT-type level of evidence when this design is ill suited or not available impedes the application of nutrition research to public health issues.
“I would argue that we can make nutrient-related decisions at a level of certainty different than required for drugs,” he concluded. “If we’re going to move forward, we have to integrate all strategies in research and use scientific judgment.” – by Nancy Hemphill, ELS