Low levels of omega-3 in blood ‘ups’ risk of dementia and brain aging: Study

By Dr. Ananya Mandal, MDFeb 28 2012

A new study shows that eating fatty fish could not only help the heart but also the brain.

Researchers looked at 1,575 adults who averaged 67 years old and had no signs of dementia and had not had a stroke. They were given MRI brain scans and a battery of tests to measure memory and thinking abilities; they also had blood drawn to check the level of docosahexaenoic acid (DHA) or omega-3 fatty acids in their red blood cells. Those with the lowest levels of omega-3s showed signs of accelerated aging. They had lower brain volume, indicating shrinkage comparable to two additional years of aging. Compared with those with the highest blood levels of omega-3s, they scored lower on cognitive tests measuring such things as memory, problem solving, abstract thinking and multi-tasking.

The study was published in the Feb. 28 issue of the journal Neurology.

“We feel that omega-3’s reduce vascular pathology and thus reduce the rate of brain aging,” said Dr. Zaldy S. Tan, the lead author and associate professor of medicine at the University of California, Los Angeles. Few in the study were taking omega-3 supplements, Dr. Tan said. The main reason that some had higher blood levels of omega-3’s was that they ate more fatty fish.

Omega-3 fatty acids are unsaturated fats found in most fish, but especially in fatty fish that live in cold seawater, such as salmon and herring. Except for trout, freshwater fish usually are lower in omega-3s.

Dr Marie Janson, from the British charity Alzheimer's Research UK, said, “There has been a lot of research into the effects of omega-3, and this study will add to that debate. One strength of this study is that it used blood samples to measure people's dietary intake of omega-3, rather than relying on answers to questionnaires to assess the link between omega-3 and cognition. However, this research does not tell us whether the people studied got worse or better over time.”

“We would need to see large-scale, long-term studies before we can know whether a diet high in omega-3 can protect against dementia, and people shouldn't fill their freezers with oily fish just yet. The best evidence for reducing your risk of dementia is to eat a healthy, balanced diet, take regular exercise and keep your blood pressure and cholesterol in check,” she said.

The limitations of the study were that most participants were white. Testing and measurements were done once, providing no data for comparison over time or to determine any link to dementia. Several of the authors have financial relationships with pharmaceutical companies.

More than 800,000 people in the UK suffer from dementia, with the majority affected by Alzheimer's disease.