Now that the days are getting shorter, we have less sun exposure, which can lead to lower vitamin D levels.  Low vitamin D levels have been associated with obesity, diabetes, heart disease, etc.  Vitamin D levels tend to be lower in darker-skinned people, and in the obese.

Now, association does not prove causation.  It’s still controversial whether or not taking extra vitamin D will reverse these trends.  I choose to take 5000U daily vitamin D.  I don’t recommend taking such doses unless under a doctor’s supervision, who can check your blood levels.  Too much vitamin D can cause heart rhythm problems.  Here are my recent vitamin D blood test results (92.7 ng/mL; normal range 30-100):

Insufficient levels of serum 25-hydroxyvitamin D (25[OH]D) appear to be a major contributor to deaths in older adults, as shown in a study showing vitamin D levels to be inversely proportional to mortality risk in these individuals (J Am Geriatr Soc. 2009;57:1595-1603). Some studies suggest that vitamin D inhibits fat deposits. Vascular health (think, impotence; heart attack; stroke) may be improved by optimizing vitamin D levels.