Nothing fishy about this

Omega-3 fatty acids found in cold-water fish like salmon, cod, herring, and mackerel have powerful anti-inflammatory and neuroprotective actions in the body. They can help ease asthma, alleviate depression, protect against heart disease, and promote healthy brain and nervous system development in infants.

The balance of fatty acids in our diets affects immune function. When the diet is higher in omega-6 fatty acids and lower in omega-3s, it’s a set up for inflammation, which in turn contributes to allergic responses and leads to allergic conditions. Diets higher in omega-3 fatty acids may lower inflammation in the body and decrease the incidence of allergies.

Australian researchers studied the effect of omega-3 fatty acids from fish oil in 706 babies at high risk for food allergies and eczema. Beginning at 21 weeks of pregnancy and continuing until the birth of the baby, women were given either 900 mg of omega-3 fatty acids per day or placebo. The fish oil capsules provided 800 mg DHA (docosahexaenoic acid) and 100 mg EPA (eicosapentaenoic acid).

When they reached one year of age, researchers determined whether the babies had developed eczema or food allergies. Skin prick tests were done to confirm allergic reactions to cow’s milk, egg, wheat, tuna, peanut, dust mites, tree pollen, grass pollen, and cat hair.

Less eczema, fewer egg allergies

Overall, the percentage of babies with allergies at one year of age was similar between the groups. However, fewer babies in the omega-3 group were allergic to eggs and fewer had eczema than those in the placebo group.

“Many of the commercially available prenatal supplements provide low doses of omega-3 fatty acids,” commented the study’s authors. “This amount is unlikely to result in the changes in [inflammatory markers] associated with higher dose omega-3 supplementation.”

Balance your fatty acids

Research into early human diets suggests that we used to consume equal amounts of omega-3 and omega-6 fatty acids. By contrast, most Western diets now contain about 16 times more omega-6 fatty acids than omega-3s.

Most of the omega-6 fats in the modern diet come from vegetable oils like corn, sunflower, and safflower oil.

Walnuts, flaxseeds, and soybeans are good non-fish sources of omega-3 fatty acids. The conversion of the fatty acids in these foods to DHA and EPA is limited, however, so it might be best to obtain at least some of the omega-3 fats in your diet from fish. Getting enough B-vitamins, vitamin C, zinc, and magnesium may enhance the conversion of vegetarian sources of omega-3 fatty acids to DHA and EPA.

(BMJ 2012;344:e184)