Obese people may need more vitamin D

Older adults with a higher body mass index have lower vitamin D levels, which needs to be taken into account when determining an adequate dietary vitamin D intake, a new UK study suggests.

In order to investigate a potential association between overweight or obesity and serum vitamin D (25-hydroxycholecalciferol) concentrations, 110 healthy young adults (between 20–40 years of age) and 102 older adults (64 years of age and older) took either 5, 10 or 15 micrograms of vitamin D or a placebo every day for 22 weeks during the winter months in this randomized controlled trial (1). The study results showed that in the older adults with a high body mass index, high waist circumference and a high percentage of body fat had low blood vitamin D concentrations at the beginning of the study and after supplementation. No such associations were apparent in younger adults.

The researchers concluded that overweight and obesity may need to be taken into account when determining an adequate wintertime dietary vitamin D intake for healthy older adults residing at higher latitudes. Past studies have already observed low levels of vitamin D in older (2) and younger (3) obese populations, which suggests the need for higher dietary intakes to meet recommended levels. A recent study showed that women with higher levels of abdominal obesity had lower blood vitamin D levels and an increased mortality risk (4). The scientists concluded that obesity and a poor vitamin D status may have a cumulative negative effect on the risk of disease.

1. Forsythe L. K. et al. Effect of adiposity on vitamin D status and the 25-hydroxycholecalciferol response to supplementation in healthy young and older Irish adults. British Journal of Nutrition. 2012; 107(1):126–134.
2. Blum M. et al. Body size and serum 25 hydroxy vitamin D response to oral supplements in healthy older adults. J Am Coll Nutr. 2008; 27:274–279.
3. Nelson M. L. et al. Supplements of 20 microg/d cholecalciferol optimized serum 25-hydroxyvitamin D concentrations in 80 % of premenopausal women in winter. J Nutr. 2009; 139:540–546.
4. Eaton C. B. et al. Prospective association of vitamin D concentrations with mortality in postmenopausal women: results from the Women's Health Initiative (WHI). American Journal of Clinical Nutrition. 2011; 94(6):1471–1478.