Health for life

People who eat farm-raised salmon can increase their intake of beneficial omega-3 fatty acids to levels that may help reduce their risk of heart disease, according to studies by U.S. Department of Agriculture (USDA) scientists.

The studies by Agricultural Research Service (ARS) nutritionist Susan Raatz and physiologist Matthew Picklo address concerns about whether farm-raised salmon have less available omega-3s than salmon caught in the wild. The scientists work at the ARS Grand Forks Human Nutrition Research Center in Grand Forks, N.D. ARS is USDAs principal intramural scientific research agency.

Two omega-3 fatty acids—EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—are abundant in oily fish such as salmon, tuna, mackerel, and herring. Consuming 250 milligrams daily of EPA and DHA—the amount in a 3-ounce farmed salmon fillet—has been associated with reduced heart disease risk.

The scientists evaluated a group of 19 healthy human volunteers who were provided three different portion sizes of farm-raised Atlantic salmon. Each volunteer was assigned to consume two weekly servings of one of the three portion sizes of salmon for a four-week period. After a "blood-clearing" break of four to six weeks, a different portion size was served, followed by another break. Then the third portion size was served, so that each volunteer had tested all three portion sizes.

The raw weights of the salmon portions fed to the volunteers were 90 grams (about 3.2 ounces), 180 grams (about 6.3 ounces), and 270 grams (about 9.5 ounces). The Dietary Guidelines for Americans recommend consuming 8 ounces of seafood weekly.

Blood was collected from each of the 19 subjects to mark fatty acid levels and other heart disease risk indicators at the beginning and end of each treatment. The results showed that EPA blood levels doubled after the volunteers consumed the 6.3-ounce portions and increased nearly threefold after they consumed the 9.5-ounce portions. Also, based on the blood indicators, DHA levels were elevated by about 50 percent, regardless of portion size.

This research was published in the Journal of the Academy of Nutrition and Dietetics.

U.S. Department of Agriculture (USDA) nutritionist Susan Raatz, physiologist Matthew Picklo, and cooperators have found that farm-raised Atlantic salmon maintains its healthy levels of omega-3 fatty acids when baked.

Two omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are abundant in oily fish such as salmon, tuna, mackerel, and herring. Some data have shown that consuming 250 milligrams daily of EPA and DHA—the amount found in a 3-ounce salmon fillet—is associated with reduced risk of heart-disease.

While eating seafood rich in omega-3 fatty acids is known to reduce risk of heart disease, it has not been known whether baking causes loss of omega-3s in farm-raised Atlantic salmon. The team also examined the extent to which baking Atlantic salmon alters healthful fatty acids through oxidation that leaves unhealthy compounds, such as toxic omega-3 oxidation byproducts.

The researchers demonstrated that baking salmon to the proper temperature does not decrease its content of beneficial omega-3 fatty acids. They found that baking actually decreases the presence of fatty acid oxidation byproducts. Preparing the fish based on restaurant and safety guidelines—to a tender-but-safe 145 degrees Fahrenheit rather than overcooking—was a key factor, according to authors.

The research was published in the Journal of Agricultural and Food Chemistry.