A recent study carried out on over 300 people reported those who eat oily fish of take fish oil supplements regularly score 13% higher in IQ tests and are less likely to show early signs of Alzheimer’s disease.

We already know that fish oil protects against heart disease and also imporves insulin sensitivity in people with a high risk of diabetes, now researchers from Scotland report that consumption of fish oil could actually improve the health of your brain and protect against Alzheimer's. Dementia already affects millions around the world and the threat is increasing with the growing numbers of elderly. Alzheimer's disease, the leading cause of dementia in the elderly, afflicts an estimated 4.5 million people in the US alone.

A team from the University of Aberdeen and the University of Edinburgh gathered data from people who had taken part in a national IQ survey in 1947, when they were aged 11, and tested them again in 2000-01 when they were aged 64. The researchers used a questionnaire to find out about omega-3 levels from the subjects' diet and supplement use, and tested their plasma levels of omega-3.

The researchers report that cognitive function in the 64-year-olds was higher if they were fish oil supplement users than if they did not take supplements. The big difference was found in mental speed. The brains of fish oil users seemed to be faster. There was a strong relationship between mental test scores and the omega-3 content in the blood. In fact, the results suggested that those who supplemented with fish oil had younger brains than those who did not.

Source: American Journal of Clin Nutrition, 2005.

Since our modern diet typically is high in omega-6 fatty acids and low in omega-3 acids, it may prudent to increase our consumption of foods that contain a higher amount of omega-3 fatty acids. The richest source of omega-3 fatty acids is fish oil from cold water fish.

If fish oil is so great, why shouldn’t everyone take supplements?

• The decreased ability of the blood to clot, which helps prevent heart attacks, has a negative side, notably an increased risk of hemorrhagic stroke. People with bleeding disorders, those taking anticoagulants, and those with uncontrolled hypertension should not take fish oil supplements.

• Large doses of fish oil may suppress the immune system. Thus, supplements may be risky for those with weakened immune systems. What’s a "large dose"? One definition is 3 grams or more a day, but no one really knows what the cutoff point is.

• Large doses can increase glucose levels in people with diabetes.

• Large doses can cause nausea, diarrhea, belching, and a bad taste in the mouth.

• The supplements may contain contaminants and may not contain the labeled dose. A recent test by Consumer Reports of top-selling supplements was reassuring on both counts, even for the least expensive brands, but that doesn’t mean that the next batches will be okay—or that other brands on the market are. Last year a test by ConsumerLab.com found no detectable levels of mercury in 20 fish-oil supplements, but did find that some brands didn’t contain the labeled amounts of omega-3s.