There’s nothing fishy about the multifaceted health benefits of omega-3 essential fatty acids. Almost weekly, medical journals publish new supportive research. Most studies focus on fish oils from salmon and other cold-water fish, the richest source of biologically active omega-3s. But some research heralds the benefits of algae-derived omega-3s, which is good news for vegetarians.

With the growing interest in omega-3s, scores of supplements now fill natural products stores’ shelves. Choice is great, but it can also be confusing. Some supplements are high in eicosapentaenoic acid (EPA), and others emphasize docosahexaenoic acid (DHA), the two key omega-3s. Although their benefits often overlap, EPA is considered a stronger anti-inflammatory agent, while DHA targets the brain more directly. Here’s how to find the right formula. (Note: Recommended doses are approximate; even quite high doses of EPA and DHA are considered safe.)

Babies to teens

The body needs EPA and DHA for normal brain and eye development prenatally and during infancy. DHA accounts for 40 percent of the fats in brain cells, according to Artemis Simopoulos, MD, director of the Center for Genetics, Nutrition, and Health in Washington, D.C. The brain requires both EPA and DHA to make neurotransmitters, brain chemicals that control moods. Older children and teens also need omega-3s; some studies have found low EPA and DHA levels interfere with learning and increase aggressive behavior.

Doses: If you’re breastfeeding, take about 400 mg DHA and 100 mg EPA; your baby will get omega-3s in your milk. For ages 2 to 10, aim for 100 mg DHA and 50 mg EPA; choose citrus-flavored fish oil or cod-liver oil. Preteens and teens need at least 200 mg DHA and 100 mg EPA; larger amounts may ease mood issues.

Women

Omega-3s can help both women and men with depression and bipolar disorder. Omega-3s also may help prevent postpartum depression. Studies suggest diets rich in EPA and DHA can reduce breast cancer risk by more than 75 percent. (Other research shows diets high in omega-6s, found in corn and other vegetable oils, actually increase breast cancer risk.) In a study of 25 women treated for breast cancer with metastases, taking large amounts of DHA lengthened survival by two to three years.

Doses: For most women, 250–500 mg EPA and 500–1,000 mg DHA should help. The breast cancer study provided 1.8 grams DHA daily.

Men

There’s no better supplement than omega-3s to reduce heart disease risk in both men and women. Omega-3s work through several mechanisms, such as by mildly thinning the blood, preventing arrhythmias, lowering triglyceride and homocysteine levels, and protecting the heart from inflammation. Although EPA appears to provide greater heart benefits, DHA also helps.

Doses: Depending on your risk factors, take 360–800 mg EPA and 100–500 mg DHA daily.

Seniors

Fish oils slow and reverse some aspects of aging. Telomeres, the protective tips of chromosomes, shorten with age, and a study in the Journal of the American Medical Association linked diets rich in omega-3s with longer telomeres. A 2010 study found that daily DHA supplements help people with age-related cognitive decline. After six months, people taking DHA had notable memory and learning improvements versus those taking a placebo. Omega-3s can reduce depression in seniors and lower the risk of macular degeneration, a blinding eye disease. Anti-inflammatory EPA and DHA can ease age-related achiness, such as rheumatoid arthritis.

Doses: To improve memory, take 900 mg DHA daily. For aches and pains, try 700 mg EPA and 350 mg DHA daily.

Vegetarians

Vegetarians and vegans tend to have lower omega-3 blood levels compared with meat eaters. Algae-sourced DHA has long been available; a new supplement (Ovega-3) contains both DHA and EPA from algae.

Doses: Follow age guidelines for other omega-3s.

Note: It’s a good idea to talk to your health care provider before starting a new supplement.