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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Improved arterial function with vitamin D

I apologize for missing a randomized controlled trial that appeared several months ago.

Researchers at the Medical College of Georgia, led by assistant professor Ryan Harris, gave 23 obese African Americans sugar pills and twenty-two others 60,000 IU of vitamin D every month for four months. They measured several different characteristics of arteries, including one that is associated with hardening of the arteries.


Harris RA, Pedersen-White J, Guo DH, Stallmann-Jorgensen IS, Keeton D, Huang Y, Shah Y, Zhu H, Dong Y. Vitamin D3 supplementation for 16 weeks improves flow-mediated dilation in overweight African-American adults. Am J Hypertens. 2011 May;24(5):557-62.

As the title implies, the function they measured – flow-mediated dilatation – actually improved with treatment. That is, vitamin D is an effective treatment for this measurement of very early hardening of the arteries. In other words, the authors found that vitamin D (and not the placebo) significantly improved arterial function. According to Dr. Harris,

“Daily dosing of 2,000 IU oral vitamin D is effective at improving vascular endothelial function in African Americans.”

As always, I found myself wanting more. To show what a low dose they used in this study, 60,000 IU/month still left 27% of subjects deficient in vitamin D. 2,000 IU/day (the equivalent of 60,000 IU/month) is just not enough to achieve optimal vitamin D health, but it is a giant step in the right direction. I believe that vitamin D in a higher dose (unlike the small dose in this study), when combined with vitamin K2 and magnesium, will slowly but inexorably reverse arteriosclerotic cardiovascular disease.

More troubling is that Dr. Harris left no discussion about what physiological doses (5,000 IU/day) might do, or what kind of greater effect the study implies. Only in a later report in Science Daily does Dr. Harris take the extra step and say,

“If you’re deficient in Vitamin D and you take supplements, you have a good probability of increasing endothelial function and therefore decreasing the risk of cardiovascular disease.”

American Physiological Society (2011, April 16). Vitamin D may help reduce heart risk in African-Americans. ScienceDaily.

We need this extra discussion. We need more discussion about the premature deaths of so many African Americans, deaths due to refusal of the US government to read the torrent of science now flooding around vitamin D.


  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

2 Responses to Improved arterial function with vitamin D

  1. donnafickel says:

    at 8000 units a day my level moved from 21 to 68… I am very pleased. Not to mention healthier. I would like to know what amount of Vit. K you suggest?

  2. jelarsen1@cox.net says:

    60,000 iu/month is 2,000 iu/day (realizing D half-life is about 3 weeks). Obesity would confound that dose’s effect on serum levels.

    My pet rock is the ‘blind dosing’ model (give everybody x whether they need it or not or if it results in therapeutic serum levels).

    Folks love to argue dosing, but D serum levels vary by: skin color, latitude, season, obesity, age, genes, diet, lifestyle (washing, clothing, activity, etc.), etc. The only thing that counts are serum levels.

    The RDA, after all, are age and gender averages, not what your unique needs are. The Lappe Navy BCT study showed athletes need 2x the calcium RDA due to sweat losses.