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Farmed salmon misses USDA vitamin D mark

BU researcher finds wild salmon delivers four times the benefit

If you want healthy bones, go wild and skip the farmed salmon. A recent study by Michael Holick, a professor of medicine at the Boston University School of Medicine, has shown that farm-raised salmon contains only 25 percent of the vitamin D found in salmon caught in the wild.

“Typically, farm fish are fed a manufactured pelleted food containing proteins, carbohydrates, and vitamin mix,” says Holick. “Wild fish have the whole food chain at their disposal.”

Vitamin D deficiency is a major problem for people of all ages and may be associated with weakening of bones, skeletal deformities in children, and fractures in adults. According to USDA food charts, a 3.5 ounce serving of salmon contains 400 to 700 international units (IU) of vitamin D3. Holick’s study found, however, that 3.5 ounces of farm-bred salmon contains only 200 IU, while the same amount of wild salmon contains 800 to 900 IU — a significant difference from the USDA chart.

The recommended daily allowance of vitamin D is 200 IU, but for those who spend most of the day in front of a computer in a dorm room or a cubicle and out of the sun, the recommended daily allowance goes up to 1000 IU. That means that a small helping of wild salmon (Whole Foods Market recommends eight ounces per person for a single serving, more than twice the USDA serving size) gives you all the vitamin D you need for the day, but it would take up to four times as much farm-bred salmon to give you a similar benefit.

The study looked at 24 farmed salmon and 20 wild-caught salmon. Wild-caught salmon usually comes from Alaska, while farmed salmon comes from sea farms, particularly on the Atlantic coast. Fish must be identified as wild or farmed when it is sold, making it easy for consumers to find the healthier fish.

Holick conducted the study with Tai Chen, professor of medicine, and Zhiren Liu, research associate, on salmon provided by Legal Sea Foods. “Legal Sea Foods has long been a proponent of wild-caught salmon,” says Holick, “and this study has opened their eyes even more to the fact that it is a good thing.”

The study results were first presented on September 15 to the American Society for Bone and Mineral Research (ASBMR). “These findings indicate that the vitamin D content in foods needs to be carefully measured and the food charts revised and updated to prevent vitamin D deficiency and risks of associated diseases,” says Steve Goldring, ASBMR president-elect.

“The farmed salmon industry needs to think of strategies to enhance the vitamin D content in their salmon so it has the same nutritional value as wild-caught salmon,” Holick says.