The epidemic of obesity among children in the United States tripled between the early 1980s and 2000. By 2008, 32% of all the children in the USA were overweight. Connections between childhood obesity and vitamin D are growing and it may in part be due to imprinting or programming, something that the vitamin D deficient mother imprints on her child during her pregnancy.
Dr. Sarah Crozier and colleagues at the Medical Research Council Lifecourse Epidemiology Unit in Southampton, England, studied 977 children whose mothers had a 25(OH)D level taken during the 34th week of their pregnancies.
Crozier SR, Harvey NC, Inskip HM, Godfrey KM, Cooper C, Robinson SM; the SWS Study Group. Maternal vitamin D status in pregnancy is associated with adiposity in the offspring: findings from the Southampton Women’s Survey. Am J Clin Nutr. 2012 May 23.
35% of the pregnant women had 25(OH)D levels lower than 20 ng/ml. When the 25(OH)D levels were split in tertiles (<20 ng/ml; >20 ng/ml but < 30 ng/ml; and > 30 ng/ml), the authors found that the offspring at six years of age were significantly more likely to be obese if their mothers were in the lowest tertile during her pregnancy six years earlier. After correcting for numerous confounding factors, the “robust” findings stood unchanged.
It now appears possible that vitamin D deficiency during pregnancy is one of the causes of the childhood obesity epidemic. If so, vitamin deficiency accomplished this through some kind of imprinting, perhaps epigenetically.
Season of the year was more important in preventing deficiency than were prenatal vitamins, which contain 400 IU of vitamin D in England. Among women who gave blood in the summer, 84% had 25(OH)D levels above 25 ng/ml; among women who gave blood in the winter, only 23% had levels above 25 ng/ml. This level, 25 ng/ml, appeared to be the threshold level, with no further improvement in childhood obesity seen with higher maternal 25(OH)D levels.
What happens to these obese six-year-olds? They, in turn, become vitamin D deficient, which is a risk factor for childhood diabetes, poor physical fitness, low peak bone mass, and other undesirable outcomes.
Moreno LA, Valtueña J, Pérez-López F, González-Gross M. Health effects related to low vitamin D concentrations: beyond bone metabolism. Ann Nutr Metab. 2011;59(1):22-7. doi: 10.1159/000332070. Epub 2011 Nov 25. Review.
If you want to reduce the risk of having overweight kids, make sure you are not vitamin D deficient during your pregnancy. In this study, they found that levels over 25 ng/ml protect against this risk. However, we recommend higher, natural levels for lots of other reasons.
On days you do not get full body sun exposure, we recommend 6,000 IU/day throughout pregnancy, 5,000 for mom and 1,000 for baby, to maintain natural vitamin D levels, around 50 ng/ml, which is about where breast milk is magically transformed into a rich source of vitamin D for the infants.