Obesity and Vitamin D

It has been awhile since I talked about vitamin D on this blog, so here are some new insights. Research published in May in the American Journal of Clinical Nutrition found that mother's who are vitamin D-deprived during pregnancy are more likely to have children who suffer from obesity. Of the 977 women in the study, the average serum level of 25 OHD (vitamin D) was 24.8 ng/ml which is about 50% of the optimal level of 50 ng/ml.  However, the vitamin D status of these women was actually worse than this since 35% of the women had serum 25 OHD levels below 20 ng/ml and were, therefore, clinically deficient in vitamin D. These women gave birth to infants who were low in both lean and fat body mass, but who, by age six, had higher levels of body fat than did the children whose mothers were vitamin D-sufficient during pregnancy.  The researchers checked for confounding factors, but found that maternal BMI and weight gain during pregnancy did not play a role.  They concluded that, "Lower maternal vitamin D status may be linked to programmed differences in offspring fat mass. The findings require replication but add to a growing evidence base for a role of vitamin D in the origins of adiposity."  That is, pregnant women who have inadequate levels of vitamin D may pre-dispose their children to obesity later in life.  It does not appear that the researchers checked the vitamin D levels of the children.  But if the mothers were deficient during pregnancy, the children would have been born vitamin D deficient.  And it is probable that their vitamin D status was not optimized during childhood, especially if the mothers followed the dermatological guidelines which prevent children from receiving UVB radiation exposure and thereby prevent them from making vitamin D by exposing their skin to sunlight.  [See my post on Dermatological Purdah for more on this issue.]

This research provides further support for an earlier study (2009) on weight loss at the University of Minnesota that found that obese individuals were vitamin D deficient. Dr. Sibley was running a diet study with 38 participants.  She found that those who were vitamin D-deficient had a much harder time losing body fat than did those with higher levels of vitamin D.  While she admits that her observational study does not provide clear evidence for a cause/effect relationship between obesity and vitamin D levels, it is suggestive.  The hormonal form of vitamin D affects the "...same pathway (the renin-angiotensin system) [that] also affects fat cell development and metabolism...What’s interesting about our study is we did not recruit people to be vitamin D inadequate; we recruited people who were overweight or obese for our weight-loss study. And they happened, on average, to have inadequate vitamin D levels, so it tells you how prevalent the problem is.”  


While more research needs to be done on this connection, vitamin D deprivation is a widespread problem in the United States, as is obesity.  If raising serum 25 OHD levels can increase weight loss and prevent childhood obesity, then this problem seems to have a relatively easy fix.  If you've taken the dermatologist's warnings seriously, but you still want to raise your vitamin D levels, then you will need to take supplements.  Make sure the supplements are vitamin D3, without calcium. Excess calcium intake via supplementation is a bigger problem than no calcium supplementation. To raise your levels to 50 ng/ml, you will probably need to take 2000 - 4000 IU/day.  It is a good idea to have your vitamin D levels checked before beginning supplementation, and then again after three months of supplementation.  Pregnant women need to take at least 5000 IU/day of vitamin D3.


If diet and exercise are not really doing the job in helping you to lose weight, try optimizing your vitamin D levels.  It may be just the kickstart you need to get you on the road to better health.