Nutritional Pearls: Do Omega-3 Supplements Protect Against Dementia?

Ronald is a 65-year-old man who is experiencing early signs of dementia.

Recently, several family members have suggested that he start taking daily supplements of omega-3 fatty acids to help improve his cognition.

How would you advise your patient?
(Answer and discussion on next page)

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Answer: Getting your vitamins (and fatty acids) from food appears to be more effective than taking a pill.

It's important to prove that treatments work, and the gold standard for doing so is the prospective controlled trial. That's when a group of people, the larger the better, are randomly assigned to the test condition (say, a new medication), or a control condition (either not taking the medication at all, or taking what is at that time the standard medication). Ideally, neither the researchers nor the participants know who has been in which group until the study is complete.

At the same time, it's just as important to know when things do not work—and again, for this, the prospective controlled trial is the gold standard.

Previous research has shown that a Mediterranean-style diet can help prevent dementia, including Alzheimer's. Some studies have attributed some of that effect to the Mediterranean diet's impact on apple-shape obesity (otherwise known as central adiposity). Other studies have looked at specific components of that diet, like fruit, vegetables, olive oil, and fish.

In one of these studies, researchers used the amounts of omega-3 fatty acids in the participants' bloodstream as a way to validate how much fish participants reported eating, raising questions about whether or not supplementation with omega-3 fatty acids could also affect cognition.

The Research

As part of a larger study on age-related macular degeneration, over 3,000 men and women at higher risk of developing the eye condition, whose average age was ~73, participated in a test of omega-3 supplements compared to placebo.¹ For 5 years the participants took their assigned supplement (or placebo), and at the start of the study and every 2 years thereafter responded to several cognitive function tests administered over the phone by trained technicians.

The cognitive test scores were grouped together to yield 1 score for each participant for each testing session. The researchers expected that there would be some decline, as is normal in this age group, but would there be a difference in the rate of decline between those who received omega-3s and those who did not?

The Results

Unfortunately for the omega-3 supplement industry, there was "no statistically significant" difference between those taking omega-3s and those who did not.

What’s The “Take Home”?

The authors noted that 5 years might not be a long enough period to assess cognitive decline, and starting treatment over the age of 70 may be too late to have an effect.

They also noted that "[i]t is possible that eating foods rather than taking any specific single supplement may have an effect." This is in line with other research we've seen regarding taking vitamin supplements, whether they're antioxidants like vitamins A, E, or C, or omega-3s: getting your vitamins (and fatty acids) from food appears to be more effective than taking a pill.

Reference:

1. Chew EY, Clemons TE, Agron E, et al. Effect of omega-3 fatty acids, lutein/zeaxanthin, or other nutrient supplementation on cognitive function: the areds2 randomized clinical trial. JAMA. 2015;314(8):791-801.