Make sure you are getting adequate vitamin D for optimal body composition! New research shows low vitamin D will make men and women fat, make children fatter if their mother’s had low D during pregnancy, and lead to less muscle mass in men. It will also compromise bone health in both genders.
A fascinating new study in the The American Journal of Clinical Nutrition tested a large group of pregnant mothers in their 34th week for vitamin D status. Then they tested their offspring for body fat percentage at 3 weeks and at 4 and 6 years of age. After accounting for confounding factors, results showed a significant relationship between mothers with low vitamin D during pregnancy and greater body fat in their children at 4 and 6 years. At 3 weeks, lower maternal vitamin D was associated with less body fat.
There appeared to be a threshold effect on body fat in the children at 6 years such that mothers with vitamin D below 25 ng/ml had offspring with significantly more body fat than the women with higher vitamin D. The children’s body fat was much lower in those whose mothers had a vitamin D level over 30 ng/ml—30 ng/ml is considered the cutoff for adequate vitamin D whereas below 20 ng/ml is generally considered a deficiency. Levels in the 50 ng/ml range are considered optimal by functional medicine doctors and the Vitamin D Council.
Researchers are unclear why maternal vitamin D leads to low body fat at birth and then an accelerated fat gain throughout childhood, but they suggest that low maternal vitamin D results in a programmed effect in the fetus that predisposes the child to gain excess body fat. This is not surprising since other studies have produced profound links between low vitamin D, obesity, and excess fat gain.
A second recent study found that bone mineral density—the primary marker of bone strength and health—was much higher in men and women with a higher vitamin D status. In males, vitamin D was positively associated with lean body mass, but not body fat. In females, low vitamin D correlated with greater body fat.
The mechanism behind this differential effect on body composition markers in men and women is unclear, but it likely has to do with the role vitamin D plays in cellular health and metabolic signaling pathways. Vitamin D interacts with every cell in the body, conveying various functions including gene signaling, and ensuring that cells replicate properly.
Take away a commitment to getting adequate vitamin D. Although vitamin D levels typically rise significantly during the summer months when we get more natural sun exposure, a large portion of the world population still has low vitamin D. The following factors put you at risk for low vitamin D: Darker skin color, wearing sunglasses, wearing sunscreen, and time of day (if you are relying on sun exposure for your vitamin D, you need to get full body sun exposure for 20 minutes between 10 am and 2 pm). To ensure you have adequate D, get tested and then supplement accordingly.
Boot, A., Krenning, E., et al. The Relation Between Vitamin D With Peak Bone Mineral Density and Body Composition in Healthy Young Adults. Journal of Pediatric Endocrinology and Metabolism. 2011. 24(5-6), 355-360.
Crozier, S., Harvey, N., et al. Maternal Vitamin D Status in Pregnancy is Associated with Adiposity in the Offspring. The American Journal of Clinical Nutrition. 2012. 96, 57-63