Fish Oil and Omega-3 Fatty Acids for Alzheimer's or Memory Loss?

Population studies have shown that people who report eating more Omega-3 fatty acids (in the form of fatty fish) seem to have a lower risk of developing dementia.   Because of this, scientists have hypothesized that fish oil supplements (or supplements containing DHA, an Omega-3 fatty acid found in fish oil and algae) could be used to treat Alzheimer’s.  So far, evidence from clinical trials doesn’t support that hypothesis, at least not much.

“The data to date does not support the use of DHA in patients with established Alzheimer’s disease,” says Dr. Joseph Quinn, Associate Professor of Neurology at Oregon Health & Science University.  Dr. Quinn led the recent Alzheimer’s Disease Cooperative Study trial which showed no benefit of DHA for people with mild to moderate Alzheimer’s.  A large Swedish trial also found no benefit to fish oil supplements for people with mild to moderate Alzheimer’s, except maybe for a small group of people with very mild Alzheimer’s. 

What about fish oil or DHA for mild age-related memory loss or for preventing Alzheimer’s?   “The jury is still out on preventive effects,” says Dr. Quinn.   Two recent studies were negative:

• In a half year Dutch study, Omega-3 fatty acid supplements did not help memory and thinking in older adults

• Results of a trial in England and Wales show that fish oil supplements in healthy older men and women did not help memory and thinking any more than a placebo.  During the two year trial period, scores on cognitive tests remained the same in both the group receiving the fish oil supplements and the placebo group.

One study was more positive.  The MIDAS (Memory Improvement with DHA Study) trial of DHA supplements showed improvements in some types of memory and thinking in older adults with mild [but normal for their age] memory problems.   It seems to me there are some reasons for caution in interpreting the results of MIDAS:

• This 24 week trial was sponsored by Martek Biosciences, the company that owns the patent on and markets the DHA supplement used in this trial and in the Alzheimer’s Disease Cooperative Study trial above.  Most of the scientists conducting the research are employees of or consultants to Martek.   

• The researchers changed the main test used to measure effectiveness in the middle of the trial

• Trial participants taking the supplement improved their scores on some parts of this second test more than those taking placebo, but both groups improved.   There were no differences between the groups on self-assessment of memory and daily living skills.

Other studies involving fish oil and memory are ongoing.  A Dutch study is underway to test how effective fish oil supplements are in treating Mild Cognitive Impairment, and to see if results differ by APOE4 status.   At Oregon Health & Science University, one of Dr. Quinn’s colleagues is planning a trial of fish oil plus lipoic acid (an antioxidant) for Alzheimer’s.

So what’s the bottom line for prevention of Alzheimer's or cognitive decline?  “I do not push it, but I also do not discourage the use of fish oil for prevention, as there is not much of a downside and potential for other health benefits,” says Dr. Quinn.

You can read about the evidence for other health benefits of fish oil, and about potential side effects and interactions with medicines and supplements, at the U.S. Government’s MedlinePlus site.

Comments

[Chiropractic Saint Paul]

Nice its really good information Thank you

[dd]

Omega 3 is known as a help for treating depression- and helps the body in lots of other things- as my grandmother used to say, "It couldn't hurt."

[DON MOYER]

It happens often. There is evidence that certain foods give a desirable effect, but extracts of key parts of those foods do not by themselves give the desirable effect.

Too bad there's no way to make big profits selling healthy diets.

[Danny George]

Great reporting, Mona, and Don, good point above. The problem is that reductionism has extended into our culinary habits, so we now think about the nutrients in food rather than food itself (Michael Pollan calls this "nutritionism". We also give insufficient attention to lifelong patterns of eating, which are much more meaningful predictors of our health than isolated supplementation, though are admittedly challenging to study.

Fish oil failures in RCTs are no different than failures in antioxidant studies on beta carotene, vitamin A,C,E, etc, and it makes you question whether we should be throwing so much money at such trials when common sense gives us a much better answer (ie. yes, humans have eaten fish for hundreds of thousands of years and therefore fish is preferable to cheeseburgers and processed foods!).

As for Dr Quinn saying "there's not much of a downside", that may be true but it's important to remember fish oil supplements can cause bleeding in some people, and can become contaminated by mercury, PCBs and other water borne toxins that leach into the skin of fish.

[dd]

I believe it will help and helps many other systems anyway- this did not test an appropriate group.