Differences in 25-Hydroxyvitamin D Concentrations May Explain the Black-White Differences
in Chronic Kidney Disease and Risk of Renal Cell Carcinoma
Epidemiology • Volume XX, Number XXX, XXX 2015
To the Editor:
The recent article by Hofmann and colleagues1 reported increased association of chronic kidney disease with renal cell carcinoma for blacks, Asians, and Hispanics, but not whites. The black-white disparity for renal cell carcinoma incidence for blacks was attributed to hypertension and chronic kidney disease. The authors recommended additional studies to evaluate the possible factors underlying the association between chronic kidney disease and risk of renal cell carcinoma. This letter outlines the evidence that racial differences in 25-hydroxyvitamin D [25(OH)D] concentrations may explain the findings.
Due to dark skin pigmentation and the fact that most vitamin D is produced in the skin through ultraviolet-B exposure, black Americans have lower 25(OH)D concentrations than white Americans.2,3 A study based on data from the Third National Health and Nutrition Examination Survey- linked Medicare claims files found that, over a 9.1-year follow-up, non-Hispanic blacks individuals “had a 2.83-fold (95% confidence interval [CI] = 1.03, 7.77) higher risk for developing (end- stage renal disease) compared with non-Hispanic white individuals. Additional adjustment for 25(OH)D levels reduced the risk by 58% (incidence rate ratio 1.77; 95% CI = 0.38, 8.21).”2
Another study using data from the same survey found a multifactor adjusted black-white systolic blood pressure difference of 4.0 mmHg; adding 25(OH) D concentration reduced the race difference to 2.9 mmHg, which was increased to 4.0 mmHg when those on antihypertensive medications were excluded. 3 Low 25(OH)D concentrations are also a risk factor for renal cell carcinoma. Blood was drawn at time of enrollment and people were enrolled between 1992 and 2000 and followed up to December 2004 to June 2010 depending on the country. The odds ratio for a doubling of 25(OH)D concentration was 0.82 (95% CI = 0.68, 0.99).4 While no results are presented for Hispanics, the finding in Ref. 1 that their risk of renal cell carcinoma with respect to hypertension and chronic kidney disease is intermediate between that for blacks and whites is consistent with the fact that they have mean 25(OH)D concentrations intermediate between blacks and whites due to having skin pigmentation intermediate between the two races.
William B. Grant
Sunlight, Nutrition, and Health Research Center San Francisco, CA wbgrant at infionline.net
REFERENCES
- Hofmann JN, Corley DA, Zhao WK, et al. Chronic kidney disease and risk of renal cell carcinoma: differences by race. Epidemiology. 2015;26:59-67.
- Melamed ML, Astor B, Michos ED, Hostetter TH, Powe NR, Muntner P. 25-hydroxyvitamin D levels, race, and the progression of kidney disease. J Am Soc Nephrol. 2009;20:2631- 2639.
- Fiscella K, Winters P, Tancredi D, Franks P. Racial disparity in blood pressure: is vitamin D a factor? J Gen Intern Med. 20n;26:1105-1m.
- Muller DC, Fanidi A, Midttun 0, et al. Circulating 25-hydroxyvitamin D3 in relation to renal cell carcinoma incidence and survival in the EPIC cohort. Am J Epidemiol. 2014;180:810-820.
See also VitaminDWiki
- Chronic Kidney disease not helped much by vitamin D provided you ignore dose size – meta-analysis Sept 2013
- 5X less risk of Kidney cancer if good ratio of Vitamin D binding protein to circulating vitamin D – Nov 2013
- Head and Neck Cancer associated with low vitamin D, especially with blacks - April 2012
- Colon cancer more likely in blacks due to differences in Vitamin D genes (wonder if more Vitamin D would help) – May 2014
The articles in Mortality and Darker Skin are here:
- US maternal death rate increasing (low D not mentioned) - March 2023
- COVID-19 mortality for Blacks is 5X that for whites in 2 LA Hospitals - July 2021
- COVID-19 was the third-leading cause of death in the US, especially in those with dark skins - April 1, 2021
- Deaths after Cancer Surgery higher in blacks (probably low vitamin D) – Dec 2020
- Shift workers 2X more likely to get COVID-19 (low Vitamin D) - Dec 2020
- COVID-19 was killing dark-skinned doctors, then they got a Vitamin D recommendation
- COVID-19 more frequent and deadly for those with dark skins (high risk of low vitamin D)
- Differences in black and non-black mortality and vitamin D – Oct 2012
- More US deaths due to cancer than heart if dark skinned – Sept 2012
- Telomeres improved when obese blacks took 2000 IU of vitamin D daily – Oct 2011
- Do blacks have a 5 year life penalty due to low vitamin D
- CVD deaths related to low vitamin D, especially in people with dark skin – 2010
The items in both Kidney and Darker skin categories in VitaminDWiki are:
- Vitamin D treatment of Chronic Kidney Disease: monthly better than daily – RCT May 2022
- 26 health factors increase the risk of COVID-19 – all are proxies for low vitamin D
- Kidney Cancer differences with skin color probably due to vitamin D differences – May 2015
- Blacks have 4X more Kidney disease than whites – probably due to low vitamin D – March 2015
- Blacks have low vitamin D and have 50 percent more kidney failure – Sept 2011
- End stage kidney disease almost 3X more likely for blacks – 2009
- Virtually all black dialysis patients with low albumin are vitamin D deficient in the winter – Mar 2010
- Majority of blacks on dialysis were vitamin D deficient - March 2010
- Lack of vitamin D closely associated with black health disparities – Nov 2010 Dr. Grant - has the following summary
| Black Disparity | 16 vs 26 ng/ml | |
| breast cancer | 1.34 | 1.26 |
| colorectal cancer | 1.43 | 1.44 |
| cardiovascular disease | 1.29 | 1.27 |
| all-cause mortality | 1.26 | 1.26 |