I have lowered my vitamin D recommendations for black people black people with type 2 diabetes based on some recent, albeit preliminary, research.
Here is the paragraph I added to the article Bones, Vitamin D, and Calcium:
A 2010 study on obese African-Americans with type 2 diabetes showed that those with higher blood levels of vitamin D had more calcification of some arteries (but not others) (35). In a related article, Vitamin D levels have different effects on atherosclerosis in blacks and whites, the lead researcher, Barry I. Freedman, MD, stated, “We should use caution when supplementing vitamin D in black patients while we investigate if we are actually worsening calcium deposition in the arteries with treatment.” That said, there has also been concern about black people not getting enough vitamin D (36). It seems prudent, then, for black people to get moderate amounts of sun and if they cannot, to supplement with smaller amounts of vitamin D, such as 250 IU per day. It seems prudent, then, for black people who have type 2 diabetes not to overdo vitamin D supplementation and take closer to the DRI until more research is conducted.
References
35. Freedman BI, Wagenknecht LE, Hairston KG, Bowden DW, Carr JJ, Hightower RC, Gordon EJ, Xu J, Langefeld CD, Divers J. Vitamin d, adiposity, and calcified atherosclerotic plaque in african-americans. J Clin Endocrinol Metab. 2010 Mar;95(3):1076-83. Epub 2010 Jan 8. (Abstract)
36. Harris SS. Vitamin D and African Americans. J Nutr. 2006 Apr;136(4):1126-9. PubMed Abstract..
