William Harris, PhD, told NutraIngredients-USA that he wasn’t surprised at the conclusions of the meta-analysis published Tuesday in JAMA. Lumping data together from a lot of smaller, flawed studies doesn’t yield a higher-quality result, he said.
“You keep looking at the same papers, summarize them and put them in a pot and stew them and you get the same result,” he said.
Harris is a researcher who invented the Omega-3 Index and developed a way to test for it. Harris, who is on the faculty at the Sanford School of Medicine at the University of South Dakota, is scheduled to give a talk on the current state of omega-3s science at a meeting of the National Lipids Society on Saturday in Charlotte, N.C. His talk will lay out how the science of omega-3s got to its current crossroads, and where we go from here.
One of the key difficulties in researching the benefits of omega-3s in humans lies in the length of time it takes for people to develop heart disease and suffer heart attacks. Parameters, such as dosages, that seemed like good ideas at the outset may be antiquated before the study is complete, he said. And the studies are expensive, making it very difficult to get a big enough sample size, Harris said.
“Some recent trials have not worked,” he said. “They have not shown a benefit of omega-3s in cardiovascular disease.”
“Many of these studies were too small. You have to have a certain number of heart attacks. If you have 10 heart attacks occur over 20 years you can’t test any hypothesis. There just aren’t enough numbers,” he said.
“The studies didn’t have enough power to really conclude that the omega-3s had no effect. They could only have the ability to conclude that they couldn’t detect an effect. That is not the same thing, but that is a subtlety that is lost on most folks, including many doctors.”
In addition, the length of the study period means the confounding factors accumulate, Harris said. For instance, the state of art of acute cardiac event treatment didn’t stand still while researchers tried to prove a benefit for omega-3s.
“The way we treat heart attack patients now, as opposed to the 90s which is when all the omega-3s stuff started coming out positive, is now when you have a heart attack they immediately put a catheter in and remove the clog open up the artery. It’s called acute angioplasty. They never used to do that. Doing that really prevents a lot of heart damage. And therefore people who undergo that procedure are much less likely to have another heart attack in the next few years. So in that context, when you give people omega-3s to try to prevent a subsequent cardiac event in those people, well, there just aren’t many events. You can’t see anything happening.”
Where do we go from here?
Better study design incorporating some of the lessons learned in these efforts that failed to find an effect could clean up a lot of these problems, Harris said. But it could take years to design these studies, perform them and get the results published. Where does a marketer of omega-3s go in the meantime?
“One thing you do is to look at the epidemiology, which is much longer term. You look at the studies that have linked fish intake or even better blood omega-3 levels to long term, 10-20-year outcomes. And there you see that higher omega-3 levels are always associated with lower risk,” he said.
“I think what you do is market on the risk-benefit ratio. The risk is still zero. There still is reasonably good hint of evidence, if not as solidly demonstrated as we’d like.”