Omega-3 supplements do not protect from dementia

It's important to prove that treatments work, and the gold standard 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), then followed for a period of time - again, the longer, the better. 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 that things do not work - and again the prospective controlled trial is the gold standard.

We've seen in previous Health & Nutrition Bites 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, ranging from fruits and vegetables or fruit juice, to eating fish.

That last article looked at the amounts of omega-3 fatty acids in the participants' bloodstream as a way to validate how much fish they reported eating. What about taking omega-3s in pill form?

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 (JAMA 2015;314(8):794-801). For five years the participants took their assigned supplement (or placebo), and at the start of the study and every two years thereafter responded to several cognitive function tests administered over the phone by trained technicians.

The cognitive test scores were grouped together to yield one 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?

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

What this means for you

The authors note 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 note that "It 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. Here are some great fish recipes for you to try so you can get your omega-3s the old-fashioned way: by eating them.

First posted: August 26, 2015