Research shines light on lesser known form of vitamin D in foods
Some people worry that they aren't getting enough vitamin D, which is critical for bone health, but they may be consuming more than they think.
Vitamin D is naturally present in foods such as salmon, trout, sardines, liver, egg yolks and cod liver oil, and it's also in fortified milk, cereal and orange juice, as well as dietary supplements. Plus, sunlight triggers the production of vitamin D and contributes to people's levels.
Now new research finds that animal foods (eggs, some meats and dairy products) that contain vitamin D also have another lesser known form of this nutrient that hasn't been measured routinely in foods, says Janet Roseland, a nutritionist with the U.S. Department of Agriculture's Nutrient Data Laboratory. She presented her findings at a July 17 symposium at IFT16: Where Science Feeds Innovation, hosted by the Institute of Food Technologists (IFT).
For years most nutrient laboratories measured only the vitamin D3 (the primary form) and vitamin D2 in foods and supplements, she says. But some foods also contain 25(OH)D, which has not typically been included as part of the total vitamin D given for foods, even though it may be two to five times more potent than D3 or D2.
So scientists at five technically-skilled laboratories in the United States and other countries used rigorous methods to analyze the content of several foods and a supplement to see if they could all obtain the same results. "We found that the labs' values were consistent in measuring 25(OH)D and other forms, so in the future we can have better measures of vitamin D's total content in foods," Roseland says. The research was funded by the USDA's Agricultural Research Service and the National Institutes of Health's Office of Dietary Supplements.
She says this additional information may one day be available in the USDA's National Nutrient Database for Standard Reference, which is considered an authoritative source of nutrient data for about 9,000 foods.