Study: Fish Oil Won't Save Your Brain

September 26, 2013

News Review From Harvard Medical School -- Study: Fish Oil Won't Save Your Brain

Fish oil may not help to protect the brain, a new study suggests. Some prior research had found a protective effect. The new study looked at levels of one omega-3 fatty acid in the blood of more than 2,100 women. These fats are found in fish and fish oil supplements. The women were age 65 or older when the study began. They had normal brain function. Omega-3 levels were tested at the beginning of the study. The women took tests of thinking and memory each year for 6 years. Researchers found no link between their blood levels of omega-3 fatty acids and changes in brain function. Women with higher omega-3 levels were not less likely to develop dementia. Specific aspects of thinking or memory also did not decline more slowly in women with higher omega-3 levels. The journal Neurology published the study. HealthDay News wrote about it September 25.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Sometimes I think our beliefs about health may have more to do with what we'd like to believe than what is actually true. 

The impact of fish oil on brain function may be an example. Wouldn't it be nice to think that omega-3 fatty acids -- major components of fish oil -- are good for your brain?  You'd have plenty of company if you did.   

Just type "fish oil" and "brain" into your favorite search engine. You'll find hundreds of articles linking fish oil to better thinking skills and improved memory. There's plenty on the prevention and treatment of dementia, depression and other brain diseases.

However, the evidence linking fish oil with brain health is indirect. In studies, there could be other reasons that people who eat more fish oil had better brain function. Perhaps they also exercised more or ate more fruits and vegetables. In addition, some studies have found no connection between intake of omega-3s and brain health.

A new study adds further skepticism about any such link. More than 2,100 women at least 65 years old had brain function tested over 6 years. Function was normal at the beginning of the study. Blood levels of a particular type of omega-3 fatty acid (called DHA 1 EPA) also were tested.

Here's what the study found:

• There was no connection between the level of DHA 1 EPA in red blood cells and the development of dementia.
• Specific types of brain function did not vary between people with high omega-3 fatty acid levels and those with low levels.
• There was no link between the rate of decline in thinking skills over time and omega-3 fatty acid levels.

This study was not ideal. Researchers studied changes in brain function over time, but they only sampled omega-3 levels at the start of the study. They might have seen different results if the study had repeated measures of omega-3 levels.  Also, this study included only women who were 65 and older. If younger people or men had been included, results could have been different. Finally, 6 years may be too short a time to see an impact.

Even if these results are valid, it's not clear they should lead anyone to change their food choices. Foods containing high levels of fish oil may have other health benefits, such as improving heart health. It's also possible that fish oil may help protect brain health in some groups, such as those with a strong family history of Alzheimer's disease. A diet that's high in fish oil also may be lower in harmful saturated fats.

What Changes Can I Make Now?

As this latest study suggests, it's not clear that increasing your intake of omega-3 fatty acids will reliably preserve brain function. But you may be able to take other measures to reduce your risk of dementia or other brain problems. For example:

• Address any issues that may increase your risk of stroke. Get your cholesterol, blood pressure and blood sugar checked. Talk to your doctor about how often to have these checked and what to do if they are not in an ideal range.
• Quit smoking. If you have trouble quitting on your own, ask your doctor. You also can check the American Lung Association's website for smoking cessation programs.
• Get regular exercise. Past research has suggested that people who are more active tend to have less dementia.
• Avoid excess weight. Some studies suggest that obesity increases the risk of dementia. Obesity also increases the risk of diabetes, high blood pressure and high cholesterol, among other health problems.
• Exercise your mind. Some experts believe that activities that challenge the brain can help keep it healthy. Examples include board games, crossword puzzles and reading.
• Consider taking a blood thinner. Some people at high risk of stroke may reduce their risk by taking a blood thinner such as aspirin or warfarin.
• Consider having surgery. People with a severely narrowed carotid artery in the neck may reduce stroke risk by having an operation to correct the problem.
• Talk to your doctor about factors that may increase your risk of stroke or dementia. Each person's risk profile is different. There may be other protective measures you can take.  

What Can I Expect Looking to the Future?

This new study won't be the last word on the role of fish oil in brain function. Until we have more definitive studies, nutritionists, public health officials and many doctors are likely to continue promoting fish oil as a part of a healthy diet. Fish oil supplements are a multibillion-dollar industry. So you are also likely to see more ads and claims of health benefits from the makers of these pills.

Does intake of fish oil really help brain function? I'd like it to be true. But, from the evidence to date, it may not be.