Extra 4,000 IU daily raised the vitamin D levels of blacks to that of whites
Vitamin D3 supplementation (4000 IU/d for 1 y) eliminates differences in circulating 25-hydroxyvitamin D between African American and white men 1,2,3,4
Elizabeth Garrett-Mayer, Carol L Wagner, Bruce W Hollis, Mark S Kindy, and Sebastiano Gattoni-Celli
1 From the Division of Biostatistics and Epidemiology, Department of Medicine (EG-M), and the Departments of Pediatrics (CLW and BWH), Neurosciences (MSK), and Radiation Oncology (SG-C), Medical University of South Carolina, Charleston, SC, and the Ralph H Johnson VA Medical Center, Charleston, SC (MSK and SG-C).
2 The contents of this article do not represent the views of the Department of Veterans Affairs or the US Government.
3 Supported in part by grants from the Gateway for Cancer Research, the Health Services Research and Development Program of the Department of Veterans Affairs, the South Carolina Clinical and Translational Research Institute, and the Biostatistics Shared Resource of the Hollings Cancer Center at the Medical University of South Carolina.
4 Address correspondence to S Gattoni-Celli, Strom Thurmond Biomedical Research Building, Room 338C, 114 Doughty Street, Charleston, SC 29403. E-mail: gattonis@musc.edu.
Background: African Americans suffer disproportionately from diabetes and cardiovascular disease and are significantly more likely to have suboptimal concentrations of circulating 25-hydroxyvitamin D [25(OH)D].
The results of epidemiologic and observational studies suggest that there is a link between vitamin D deficiency and the risk of cardiometabolic disorders, which underscores the importance of maintaining healthy concentrations of 25(OH)D.
Objective: The objective was to investigate whether daily supplementation with 4000 IU vitamin D3 for 1 y would eliminate any disparities in circulating concentrations of 25(OH)D between African American and white men.
Design: Serum concentrations of 25(OH)D were measured every 2 mo in 47 subjects who received a daily oral dose of 4000 IU vitamin D3 for 1 y.
Results: More than 90% of African Americans had serum concentrations of 25(OH)D <32 ng/mL, and approximately two-thirds had serum concentrations <20 ng/mL. Furthermore, there were significant disparities in serum concentrations of 25(OH)D between African American and white men.
Supplementation with 4000 IU/d for 1 y eliminated any significant differences in circulating concentrations of 25(OH)D between African American and white men.
Conclusion: The results of this clinical study show the feasibility and efficacy of this approach in the elimination of hypovitaminosis D, which is a widespread health disparity among African Americans.
This trial was registered at clinicaltrials.gov as NCT01045109
Fig 1 Increase in 2 months

Changes in 25(OH)D from baseline to 2 mo after beginning supplementation.
African American subjects (n= 12) are represented by solid black symbols;
white subjects (n = 35) are represented by open symbols.
Fig 2 Increase in a year of taking 4,000 IU daily

Effects of 1 y of vitamin D3 supplementation at 4000 IU/d on circulating concentrations of 25(OH)D.
African American subjects (n= 12) are represented by solid black circles;
white subjects (n= 35) are represented by open circles.
Each fitted line is based on the exponential model.
This Clinical Trial was for Prostate Cancer , so will have elderly men.
No information about amount needed for obese, younger, other latitudes, women, etc.
Comment on Fig 1: While the body may be consuming lots of vitamin D that 2 months after getting 4,000 IU per day
1) About 30% of whites had < 20 ng increase in vitamin D levels
2) A few whites had < 5 ng increase or even a decrease in their vitamin D levels
3) Most blacks got more of a response than whites - 20-30 ng increase
4) Most blacks started with lower vitamin D levels (as expected)
Comment on Fig 2
Yes, black and whites ended up with similar distribution of vitamin D level
Wonder why the vitamin D levels dropped significantly toward the end of the year
- Stop taking the vitamin D?
See also VitaminDWiki
Inflammation in African Americans not reduced with 3 months of 4000 IU of vitamin D – RCT Dec 2013
Dark skinned people may not need as much vitamin D – April 2012
Improved blood flow in blacks with just 2000 IU of vitamin D – Feb 2011
Blacks may not need as much Vitamin D many articles
Africans in Europe might only need 19 ng of vitamin D – estimated from PTH July 2011
20 ng of vitamin D is enough for African American PTH – Dec 2011
Perhaps just 40 ng of vitamin D if high latitude or dark skin
Traditionally living Africans have 46 ng vitamin D levels – Jan 2012
Low risk Prostate Cancer decreased with 4,000 IU of vitamin D – July 2012 another article on Prostate Cancer by same author
Many healthy African Americans got above 33 ng with 4,000 IU of vitamin D – RCT March 2014