January 23, 2014
News Review From Harvard Medical School -- Omega-3's May Help Preserve Brain Cells
Women who consume high levels of omega-3 fatty acids may be less likely to lose brain cells as they get older, a new study suggests. Omega-3 fatty acids are found in fish oil and some supplements. Researchers measured omega-3 levels in the red blood cells of more than 1,000 older women. Their average age was about 70. Eight years later, they were given MRI scans of the brain. Women with high levels of omega-3 fatty acids had larger brains than those with low levels. The difference was equal to about 1 or 2 years of normal brain shrinkage for adults in this age group. Women with higher omega-3 levels also tended to have a larger hippocampus. This part of the brain has a major role in memory. It begins to shrink early for someone with Alzheimer's disease. The new study only shows a link between higher omega-3 fat levels in the bloodstream and larger brain size. It does not show that one causes the other. Researchers also did not test women's memory or other brain functions. The journal Neurology published the study. HealthDay News wrote about it January 22.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
If keeping your brain sharp well into old age were as easy as eating more fish or taking a fish oil supplement, would you do it? I might. But I'd also want to know how good the evidence is that it would work.
A new study provides support for the idea that consuming more omega-3 fatty acids might delay age-related loss of brain function. These fats are found in fish oil and many supplements.
The medical journal Neurology published the study in its latest issue. Researchers measured 2 types of omega-3 fatty acids in the blood of more than 1,100 women. Their average age was 70. Eight years later, each woman had a brain MRI scan.
Compared with the women who had the lowest levels of omega-3 fatty acids, those with higher levels had larger brains. The difference in brain size was comparable to delaying age-related loss of brain tissue by 1 to 2 years.
The size of the hippocampus, an area of the brain involved in memory, was particularly well preserved. This may be important because the hippocampus tends to shrink early in the course of Alzheimer's disease.
These findings are encouraging. But they don't prove that consuming more fish oil (whether by diet or pills) is actually helpful. That's because:
- This study relied on omega-3 fatty acid levels measured 8 years before the MRI. Fatty acid levels can change over time, especially if there are changes in diet or supplement use.
- Small differences in brain size do not accurately predict who will develop dementia. People with brain shrinkage appear to have a higher risk of Alzheimer's disease. But shrinkage also occurs among aging adults who have normal brain function.
- This study assessed brain size, not function. Previous studies related to omega-3 fatty acids and dementia have not had consistent results. Some research did not find better memory or reasoning among those with higher blood levels of omega-3 fatty acids.
- This study did not find out how much fish oil people consumed. So the relationship between fish oil consumption and blood levels of fish oil can't be determined from this study.
- The study included only women. The results could have been different if men had been included.
More research will be needed to make a stronger case that omega-3 fatty acids can improve brain health or delay loss of brain function with age. Of course, many people aren't waiting. They argue that consuming more omega-3 fatty acids now makes sense even as we await proof of benefit.
What Changes Can I Make Now?
While we await more research about omega-3 fatty acids, you can take other steps to help preserve brain health. Here's what you can do:
- Change your diet. Eating lots of fiber, fruits and vegetables has been linked to a lower risk of Alzheimer's disease. It may be a good idea to add fish that are high in omega-3 fatty acids to this list.
- Reduce your risk of stroke. Get your cholesterol, blood pressure and blood sugar checked. Talk to your doctor about what to do if they are not in ideal ranges. A blood thinner may be recommended for some people who have a high stroke risk.
- Quit smoking. If you have trouble quitting on your own, ask your doctor about smoking cessation programs and medicines that can help.
- Exercise regularly. Previous research has suggested that people who are more active are less likely to have dementia.
- Avoid excess weight. Past studies suggest that obesity may increase dementia risk. Obesity can also increase the risk of diabetes, high blood pressure and high cholesterol. And each of these can raise your risk of stroke.
- Keep your mind active. Dementia seems to be less common among those with busy social lives and hobbies. There is some evidence that mentally challenging activities (such as memory training programs) can keep the brain healthy. However, their overall benefit is uncertain.
While it's not yet clear that omega-3 fatty acids can keep your brain healthy, there could be other benefits. Some people take fish oil supplements for heart health. A study last year even suggested omega-3 fatty acids might reduce the risk of diabetes.
You may wonder whether there are any downsides to omega-3 fatty acids. They are safe for most people, but large doses may cause bleeding. Some pills are expensive and some have a strong fish odor. If you eat fish, choose those that are high in omega-3 fatty acids and lower in mercury. Salmon is one example.
What Can I Expect Looking to the Future?
It seems likely that omega-3 fatty acids will continue to be a focus of research for brain health and other potential benefits. I hope we'll find that they stave off dementia or even reverse it. Considering the aging of our population and rising rates of dementia, even a small effect could be big news.