Over the last 10 years, studies have associated low blood levels of vitamin D with a higher risk of cardiovascular disease, death, type 2 diabetes, some cancers, infections, autoimmune diseases, frequent falls in the elderly, and dementia.
The Institute of Medicine (in the U.S.) currently recommends 200 IU (international units) per day for people under 50, 400 IU for people 50-70, with an upper intake level of 2,000 IU per day. I assume those amounts refer to a combination of food (or supplements) and the vitamin D your skin makes (but how do we know that?).
The new recommendation is expected to be around 1,000-2,000 IU per day. It’s quite difficult to get close to that just with food. With adequate sun exposure, we can make some vitamin D. But the dermatologists have scared us out of the sun with horror stories of skin cancer. I’ve seen some tragic cases in my own patients. Skin covered with sunscreen doesn’t make vitamin D. It can be difficult to get enough sun exposure, especially at higher latitudes in winter
I reviewed scientific articles pertinent to tyepe 2 diabetes via PubMed and list the best ones for you below. The evidence in favor of using vitamin D and calcium supplements to prevent diabetes is weak, but may be correct.
I found nothing to suggest that high vitamin D and calcium intake (whether food or supplements) helps control established cases of diabetes.
If you want to prevent type 2 diabetes with supplements, 1000 IU of vitamin D and 800-1000 mg of elemental calcium daily might help. The evidence is not strong. It might help; it might not. But it’s unlikely to hurt. Check with your personal physician first. More studies are needed. Calcium supplements are routinely recommended by expert nutrition panels for people over 60 to prevent osteoporosis. The vitamin D supplement may be healthy in other ways.
Who, in particular, might want to prevent type 2 diabetes? People with . . .
I’m sufficiently convinced about the nondiabetic vitamin D benefits that I’m going to start taking 1,000 IU per day.
Steve Parker, M.D.,
Pittas, Anastassios, et al. The effects of calcium and vitamin D supplementatinon on blood glucose and markers of inflammatin in nondiabetic adults. Diabetes Care, 30 (2007): 980-9896.
Chowdhurry, T.A., et al. Vitamin D and type 2 diabetes: Is there a link? Primary Care Diabetes, April 21, 2009 (Epub ahead of print).
Pittas, Anastassios, et al. Vitamin D and calcium intake in relation to type 2 diabetes in women. Diabetes Care, 29 (2006): 650-656.
Knept, P., et al. Serum vitamin D and subsequent occurrence of type 2 diabetes. Epidemiology, 19 (2008): 666-671.
de Boer, I.H., et al. Calcium plus vitamin D supplementation and hte risk of incident diabetes in the Womens’ health Initiative. Diabetes Care, 31 (2008): 701-707. (Epub January 30, 2008).