Once again, a study finds that a supplement has no benefit - here omega-3 supplements did not slow cognitive decline in older adults. On the other hand, studies find that eating foods with omega-3 fatty acids (such as fish) has beneficial health effects. Regular consumption of fish is associated with lower rates of age-related macular degeneration (AMD), cardiovascular disease, and possibly dementia. From Science Daily:
While some research suggests that a diet high in omega-3 fatty acids can protect brain health, a large clinical trial by researchers at the National Institutes of Health found that omega-3 supplements did not slow cognitive decline in older persons. With 4,000 patients followed over a five-year period, the study is one of the largest and longest of its kind.
Dr. Chew leads the Age-Related Eye Disease Study (AREDS), which was designed to investigate a combination of nutritional supplements for slowing age-related macular degeneration (AMD), a major cause of vision loss among older Americans. That study established that daily high doses of certain antioxidants and minerals -- called the AREDS formulation -- can help slow the progression to advanced AMD.
A later study, called AREDS2, tested the addition of omega-3 fatty acids to the AREDS formula. But the omega-3's made no difference. Omega-3 fatty acids are made by marine algae and are concentrated in fish oils; they are believed to be responsible for the health benefits associated with regularly eating fish, such as salmon, tuna, and halibut.* Where studies have surveyed people on their dietary habits and health, they've 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 explained.
Omega-3 supplements are available over the counter and often labeled as supporting brain health. A large 2011 study found that omega-3 supplements did not improve the brain health of older patients with preexisting heart disease.
With AREDS2, Dr. Chew and her team saw another opportunity to investigate the possible cognitive benefits of omega-3 supplements, she said. All participants had early or intermediate AMD. They were 72 years old on average and 58 percent were female....Participants were given cognitive function tests at the beginning of the study to establish a baseline, then at two and four years later.... The cognition scores of each subgroup decreased to a similar extent over time, indicating that no combination of nutritional supplements made a difference.
* Other omega-3 fatty acids are found in plant foods such as flaxseed, walnuts, soy products, and canola and soybean oils. Specific omega-3 fatty acids from these sources were not studied.