What to Know About Omega-3s and Fish
Experts explain which fish are best for omega-3s, and which you should limit due to mercury.
Powerful Health Benefits of Omega-3s
Many studies documenting the benefits of omega-3s have been conducted with supplemental daily dosages between 2 and 5 grams of EPA and DHA, more than you could get in 2 servings of fish a week. But that doesn't mean eating fish is an exercise in futility. Many studies document its benefits. For example, a 2003 National Eye Institute study showed that 60- to 80-year-olds eating fish more than twice a week were half as likely to develop macular degeneration as those who ate no fish at all.
Here's a sample of other recent studies on omega-3s and fish.
Omega-3 Fatty Acids as Brain Food
DHA is one of the most prevalent fatty acids in the brain. This could partly explain why our brains do better with a greater supply. A Rush Institute for Healthy Aging study analyzed fish-eating patterns of more than 800 men and women, ages 65 to 94. Those eating fish at least once a week were much less likely to develop Alzheimer's disease than those who turned up their nose at it.
Another study of more than 2,000 Norwegians, ages 70 to 74, used food-frequency questionnaires to evaluate consumption of five different types of fish. The researchers then conducted cognitive tests. Those who ate fish of any kind were two to three times less likely to perform poorly on the tests.
Investigators at the University of Kuopia, Finland, and at Harvard Medical School looked at the incidence of silent brain damage in about 3,500 people age 65 or older. Eating tuna or other non-fried fish was associated with a 25% lower risk of these abnormalities, which are linked to higher rates of stroke and cognitive decline.
While omega-3 fatty acids have a number of benefits, these studies do not prove a cause and effect, only that there is an association between eating fatty acids in fish and the risks of Alzheimer's disease or the risks of dementia.
Cancer Prevention With Omega-3s
Among 1,300 Swedish men, those who ate salmon and similar fish, such as herring or mackerel, had a much lower risk of developing prostate cancer than those who didn't eat fish. Those eating five or more servings a week had a 64% lower risk of the disease.
Omega-3s for Healthier Arteries
Following postmenopausal women in Finland and the United States, investigators found that those eating two or more servings of fish each week had healthier arteries than women who ate less than two servings. Benefits were even greater in those eating tuna or another type of dark fish at least once a week.
To Fish or not to Fish: Weighing the Benefits and Risks
Mercury and polychlorinated biphenyls (PCBs) are common toxins in seafood. Although the U.S. banned the use of PCBs and DDT in 1976, these and other chemicals are still used in half the world's commercial chemical processes. Substances like these can hang around in the air, soil, and water for many years. They end up in the bodies of fish and animals.