A large, nationwide, government-funded clinical trial designed to measure the effect of select nutrients on visual function – specifically age-related macular degeneration – recently reported that 1,000 mg of EPA and DHA omega-3 a day did not slow loss in cognitive decline. The other nutrients didn’t show benefit, either.
I don’t get why they thought it would. Here’s why.
Results from the second Age-Related Eye Disease Study (AREDS) published last week were not on age-related eye conditions; instead, the findings were on cognitive health. Why would a study designed to investigate eye health publish results on cognitive health? Good question. The researchers realized that they had carefully selected nearly 4,000 subjects to participate in an eye research study and were set up to follow them for 5 years; it made efficient sense to measure additional outcomes.
The subjects were between ages 50-85 and already in early or intermediate stage of age-related macular degeneration (AMD); the average age of the subjects was 72 and over half were women. The 8th decade of life is about when people begin to experience loss in cognitive function.
In the study, the subjects were given omega-3 (350 mg DHA and 650 mg EPA) and/or lutein and zeaxanthin or placebo (blank pill). The researchers completed interviews and tested cognitive function in the subjects at the beginning of the study and then each 2 years. They assessed qualities such as immediate and delayed recall, attention and memory, and processing speed. Because the subjects already had AMD and were at risk for getting worse, they were offered additional vitamins and minerals (vitamin C and E, zinc and copper). At the end of the study, the reported that the supplements did not slow decline in cognitive function.
Here’s why I’m not surprised:
- Diet matters. Studies consistently report that people who have healthy levels of EPA and DHA omega-3 over their lifetime have better cognitive function as they age. Other studies have shown that around the age of 50, people who have higher DHA levels have better cognitive health compared to those with lower DHA levels.
- The subjects were already diagnosed with age-related macular degeneration (AMD). That the subjects had AMD suggests that, like many Americans, they had consumed little EPA and DHA in their lifetime because having higher levels of these long-chain omega-3s is associated with lower risk of AMD.
- The amount of omega-3 was too low. The investigators didn’t measure blood levels of omega-3 or dietary intake of omega-3 foods during the study; that’s understandable since it would be cost prohibitive, but they did measure how many of the subjects actually took the supplements and they measured omega-3 blood levels in a representative group. This is customary in these types of studies and it’s the responsible thing to do. What they found is that about 80% of the subjects (4 out of 5) took the supplements about 75% of the time. So few, if any of the subjects actually got the intended amount of EPA and DHA omega-3 (350 mg DHA and 650 mg EPA). When the investigators measured blood levels, they did see increases in those who took the omega-3. That’s good, it means the supplements actually contained omega-3. Studies show cognitive benefit among adults with at least 1,000 mg DHA. One gram, less than ¼ teaspoon of oil.
Bottom line: Giving a small amount of omega-3 to people already demonstrating the effects of a lifetime of low levels of omega-3 for 5 years won’t reverse cellular damage that’s been done. What we do know, is that consuming omega-3 over the lifetime DOES make a difference, and/or consuming higher levels later in life DOES make a difference.
Further, the research investigators acknowledged that studies that have surveyed people on their dietary habits and health have found that regular consumption of fish is associated with lower rates of AMD, cardiovascular disease, and possibly dementia. “We’ve seen data that eating foods with omega-3 may have a benefit for eye, brain, and heart health,” Dr. Chew, study author, explained.
Adam Ismail, the Executive Director of the Global Organization of EPA and DHA Omega-3 also makes some excellent points in this summary https://www.linkedin.com/pulse/omega-3s-cognition-dosage-matters-adam-ismail.
Perhaps some of the greatest damage done by this study was the article published in Newsweek with the heading “Omega-3 supplements are a waste of money”. I find it unfathomable that a ‘health’ reporter would make such sweeping and inaccurate conclusions from one study. She’s wrong. She’s evidently unaware of the 3 decades of research. What’s most upsetting to me is that she has used her influence to do harm. Yep, to damage public health. There are people who need omega-3 supplements but I bet she doesn’t know who they are. Unfortunately, she’s not available to contact. I tried.
Gretchen Vannice, MS, RDN
Nutrition Consultant
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