Beyond the Heart, What Else Can Omega 3s Do?

By JEANNE WHALEN

WSJ Sept. 15, 2009

Many a carton of milk or yogurt now brags of its fortification with omega 3s, a trend that has made the dietary additive seem like just the latest marketing gimmick for health-minded consumers.

But omega 3s, a family of unsaturated fatty acids, have been shown to reduce the risk of coronary heart disease. And now, the compounds are being studied by scientists around the world as potential treatments for a wide range of other serious conditions, ranging from Alzheimer's disease to epilepsy and rheumatoid arthritis. Further research also is being done on omega 3s' role in preventing heart disease to determine the full range of potential benefits.

University of Birmingham

In an experiment, omega 3s block white blood cells from moving out of a blood vessel (left). Without omega 3s (right), the cells move readily.

Omega 3s are found naturally in fatty fish such as salmon, mackerel and sardines, and in some botanical sources such as flaxseed and kiwi fruit. A variety of firms also sell omega 3s as dietary supplements. Scientists say the benefit to the body should be the same whether they are consumed through food or capsules. Many scientists believe omega 3s provide health benefits in part by reducing inflammation, which can contribute to heart disease, arthritis and other ailments. But researchers are still attempting to understand how exactly omega 3s interact with the body. And studies for a number of medical conditions aren't far enough along to know whether the fatty acids could be beneficial.

One research team in the U.K. recently experimented on human cells in artificial blood vessels to try to understand what role omega 3s play in inflammation. The researchers used a glass tube to mimic a blood vessel. Normally, inflammation occurs when white blood cells migrate from the blood, through the blood-vessel wall and into surrounding tissue. The researchers coated their glass tube with endothelial cells, which normally line the interior walls of blood vessels. Then they added omega 3s to the endothelial cells.

Later, when the researchers pumped white blood cells into the tube, they saw under a microscope that the cells couldn't get across the endothelial barrier—the omega 3s were blocking them, according to a paper published in online journal PLoS Biology last month. When they performed the same experiment without the added omega 3s, the white blood cells easily penetrated the endothelial barrier.

More Research Needed

More research is needed to determine if the omega-3 blockade similarly occurs in actual blood vessels. But Ed Rainger, a cellular immunologist at the University of Birmingham Medical School, who led the research, says the experiment shed light on how inflammation works in the body and how tweaking the diet might affect it. He added that the discovery could eventually help scientists develop new medicines that block inflammation, which could be useful in treating diseases such as rheumatoid arthritis and psoriasis.

Inflammation plays a role in many areas of heart disease, which is probably at least partly why clinical trials have shown that omega 3s can reduce rates of heart attacks and strokes and slow the buildup of harmful plaque in the arteries, says Stephen Nicholls, a cardiologist at the Cleveland Clinic in Ohio.

Omega 3s appear to have benefits beyond reducing inflammation. They also lower levels of potentially harmful blood fats called triglycerides, which are unrelated to inflammation but can increase risk for heart disease, Dr. Nicholls adds. A prescription-strength pill called Lovaza, made from omega 3-containing fish oil, is approved for sale in the U.S. for reducing triglycerides.

Many scientists also believe that omega 3s might help stabilize cells and prevent them from generating erratic electrical signals in the heart and brain, which can cause irregular heartbeats, seizures and other problems.

Christopher DeGiorgio, professor of neurology at University of California, Los Angeles, has been testing this theory in epilepsy, with mixed success. In past studies, omega 3s haven't helped much to reduce seizures, he says. In a new study of 30 epileptics, he hopes to show that omega 3s reduce rates of sudden death. Sudden death—when an epileptic dies suddenly with no clear cause—accounts for about 20% of all deaths among epileptics, and irregular heartbeat can contribute to it, Dr. DeGiorgio says. He wants to test whether omega 3s help stabilize the heart and thus reduce cases of sudden death.

Some experiments on animals have suggested that omega-3 consumption can reduce brain levels of the amyloid proteins associated with Alzheimer's disease. These findings have helped drive researchers to study omega 3s in Alzheimer's patients, too.

One study involving 400 Alzheimer's patients, presented at the International Conference on Alzheimer's Disease in Vienna this summer, showed mixed results. A daily dose of two grams of DHA, one type of omega 3 fatty acid, for 18 months did not help patients perform better than those taking a placebo on standard tests used to assess the disease.

But in an interesting twist, patients taking DHA who didn't have a gene variant called ApoE4 did experience a slower rate of decline on one test of mental function compared with patients taking a placebo. Joseph Quinn, associate professor of neurology at Oregon Health & Science University and the leader of the study, cautions against making too much of this finding for now. But he says it's "encouraging and intriguing" that at least some patients seemed to benefit from omega 3s and says he hopes to conduct new studies to "look at that genotype more carefully." At least one-third of people with Alzheimer's disease lack this gene variant, according to the National Institutes of Health.

Dietary supplements usually contain about 200 milligrams of omega 3s per capsule, while a fatty salmon steak can contain up to one gram, according to Maria Makrides, an expert on omega 3s at Women's and Children's Health Research Institute in Australia.

Dietary Advice

The American Heart Association recommends that people without coronary heart disease eat a variety of fish at least twice a week, and include other foods such as flaxseed and walnuts in the diet. It says people with documented heart disease should eat about one gram of omega 3s a day. The AHA says that while omega 3s are generally safe, some side effects can include a fishy aftertaste, gastrointestinal disturbances and nausea. It says that while most omega-3 supplements are "essentially" free of mercury, the toxic metal sometimes found in fish, some poorly made supplements can contain "appreciable amounts."