|Taylor, Christine - National Institutes Of Health (NIH)|
|Patterson, Kristine - University Of Maryland|
|Wise, Stephen - National Institute Of Standards & Technology (NIST)|
|Merkel, Joyce - National Institutes Of Health (NIH)|
|Yetley, Elizabeth - National Institutes Of Health (NIH)|
Submitted to: Journal of Nutrition
Publication Type: Research Technical Update
Publication Acceptance Date: 2/19/2014
Publication Date: 3/12/2014
Citation: Taylor, C.L., Patterson, K.Y., Roseland, J.M., Wise, S.A., Merkel, J.M., Pehrsson, P.R., Yetley, E. 2014. Including food 25-hydroxyvitamin D in intake estimates may reduce the discrepancy between dietary and serum measures of vitamin D status. The Journal of Nutrition. doi:10.3945/jn.113.189811.
Interpretive Summary: 25-hydroxyvitamin D (25(OH)D), the metabolized form of vitamin D, is present in animal-based foods such as meat, poultry, and eggs. For the most part, levels of 25(OH)D in foods have not been determined in the US and, therefore, have not been included when reporting the vitamin D content of foods. The extent to which 25(OH)D intake makes a contribution to vitamin D status, as well as the amount of 25(OH)D in animal-based foods need exploration, especially because these foods are consumed frequently in the US. Current public health concerns exist due to estimates of total vitamin D intake from foods and dietary supplements, which suggest that many people in the US consume considerably less vitamin D than the established dietary requirement. At the same time, serum 25-hydroxyvitamin D (25(OH)D) concentrations of the population, which indicate vitamin D status, are higher than expected based upon the estimated amount of vitamin D consumed. The discrepancy between these commonly used measures of vitamin D status—intake and serum 25(OH)D concentrations—has been puzzling. Sun exposure increases serum 25(OH)D concentrations, and is often used to explain high population-based serum concentrations among people with apparently low vitamin D intake. However, sun exposure may not be the total explanation. Recently, preliminary USDA data for 25(OH)D content of a subset of foods became available, so that 25(OH)D values could be studied in the context of the potential for change in reported vitamin D content of foods. 25(OH)D in foods has been suggested to be 2 to 5 times more potent than the parent vitamin D in raising serum 25 (OH) D concentrations, so the impact of 25 (OH) D potency was addressed. Mean amounts of beef, poultry, and eggs, estimated as intakes of these foods within broad commodity groups, were used to project trends when 25(OH)D content in these foods was included in vitamin D intake calculations. Overall, including 25(OH)D amounts as part of total vitamin D suggested sizeable increases in vitamin D content for some animal-based foods. In turn, there was a potentially meaningful increase (15-25% of requirement) in vitamin D intake estimates, which could reduce discrepancies between intake estimates and serum 25(OH)D concentrations. The relevance to dietary intervention was discussed, as well as challenges for determining 25(OH)D in foods.
Technical Abstract: The discrepancy between the commonly used vitamin D status measures—intake and serum 25(OH)D concentrations—has been perplexing. Sun exposure increases serum 25(OH)D concentrations, and is often used as an explanation for the higher population-based serum concentrations in the face of apparently low vitamin D intake. However, sun exposure may not be the total explanation. 25-hydroxyvitamin D (25(OH)D), a metabolite of vitamin D, is known to be present in animal-based foods. Nonetheless, it has been measured and reported only sporadically, and at this time it is not factored into US estimates of vitamin D intake. Previously unavailable preliminary USDA data specifying the 25(OH)D content of a sub-set of foods allowed exploration of the potential change in the reported vitamin D content of foods when 25(OH)D values were included in the calculations for content. The question of 25(OH)D potency was addressed, and available commodity intake estimates were used to outline trends in projected vitamin D intake when 25(OH)D in foods was taken into account. Overall, given the data available, inclusion of 25(OH)D measures suggested sizeable increases in the total vitamin D content of at least some animal-based foods. In turn, there was a potentially meaningful increase (15-25% of requirement) in vitamin D intake estimates, an increase that could reduce discrepancies between intake estimates and serum 25(OH)D concentrations. The relevance to dietary interventions was discussed as well as challenges for determination of 25(OH)D in foods.