Fat folks more likely to be Vitamin D-deficient?

I got a phone call from my RNP; my screening tests show no problems, but my vitamin D is still a little low.  She suggested I continue to take a 1000iu Vitamin D tablet a day.   During my checkup RNP also urged me to start taking a multivitamin again.  I have, and it has 400iu of vitamin D too.  So now I’m actually getting 1400 iu of Vitamin D a day from pills, plus whatever’s in milk and fish.

I began to wonder if this was too much, so I started playing with Google…and found that being fat is correlated with increased risk of vitamin D deficiency.

  • Producing from sunlight. One study compared how much vitamin D fat women produced from UVB rays vs “normal” weight women. Both groups increased their vitamin D levels, but the increase in vitamin D from the simulated sunlight was 57% lower in the fat women.  (Chart – note “BMI” should be “Body weight (kg)”.)   This implies that fat people need more sun exposure to produce the same amount of vitamin D.
  • Absorbing from pills. The study also compared how much vitamin D was absorbed from oral supplements.  Again, both the fat and thin women increased their vitamin D levels, but the thin women absorbed more.  (Chart – note “BMI” should be “Body weight (kg)”).   This implies that fat folks need higher oral doses of vitamin D.

*headdesk*

Well, being fat may be one reason why my vitamin D levels are low.  But there are others. Continue reading