Looking over years of data

The researchers selected 26 trials from the past decade in which omega-3 fatty acid supplements were compared to placebo. Ten of the studies looked at the effects in healthy adults, while others looked at the effects in people with heart disease, diabetes, kidney disease, Alzheimer’s disease, sepsis (an infection in the blood), and acute pancreatitis. The fatty acids used in the studies were those most commonly found in fish oil—EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—and the amounts ranged widely from 120 mg per day to more than 20 grams per day. The studies lasted anywhere from two days to six months.

Benefits seen in certain people

People with chronic kidney disease, acute sepsis, and acute pancreatitis appeared to benefit from omega-3 fatty acid supplements. Taking omega-3 fats consistently led to decreased levels of certain inflammatory markers in people with cardiovascular disease who used the supplements for 12 weeks or more; however, because of the variety of study methods, the researchers were not able to determine the exact amount needed for a benefit.

There was not enough evidence to say whether omega-3 fats were helpful in people with Alzheimer’s disease. In healthy people, omega-3 fats had no effect on levels of inflammatory markers, except in healthy exercisers: in this group, the usual post-exercise spike in inflammatory chemicals was blunted by taking omega-3 fats.

Take omega-3 fats wisely

Here are some things to consider if you are thinking about taking omega-3 fatty acid supplements:

• Inflammatory conditions are likely to improve. Reductions in inflammatory markers are likely to translate into fewer or milder inflammatory symptoms and slower disease progression in people with conditions such as heart disease, diabetes, asthma, rheumatoid arthritis, inflammatory bowel disease, and cancer.
• Look to the American Heart Association. The AHA recommends that healthy people eat fish at least twice per week. They also recommend an additional 1,000 mg of EPA and DHA every day for people with heart disease, and 2,000 to 4,000 mg per day for people with high cholesterol levels or high blood pressure.
• Use omega-3 fats with care. If you take too much, you may increase your risk of bleeding. People with bleeding disorders or who take blood-thinning medications such as warfarin (Coumadin®), clopidogrel (Plavix®), or aspirin should check with a healthcare practitioner before starting an omega-3 fatty acid supplement.

(Br J Nutr 2012;107:s159–70)