African Americans Need Less Vitamin D and Calcium

Calcium and vitamin D are two of the cornerstones of bone health — vitamin D helps calcium get absorbed into the body where it provides the mineral strength in bone. Calcium metabolism is a very dynamic process and genetics play a strong role. Because of differences in genetics, African Americans may not require the same amount of calcium and vitamin D to maintain good bone health as other ethnic groups.    

Ethnic differences in calcium metabolism and vitamin D

In 2010, researchers found that the level of vitamin D that triggers a kind of warning message to the body’s calcium metabolism in African American women is about 23% lower than the trigger level in white women.  On average, in African Americans they found that the vitamin D level was 15 ng/mL compared to 24 ng/mL in whites.  These findings were confirmed in a 2011 study ² and suggest that African Americans can get by with a lower level of vitamin D than whites.

The Woman’s Health Initiative also studied racial differences with vitamin D and bone health.³  Researchers looked at a variety of factors in women who had fractures. White women with the highest level of vitamin D (25(OH)D >30 ng/mL) had a 44% lower risk of fracture compared with white women who had the lowest level (25(OH)D <20 ng/mL).  In contrast, African American women with highest level of vitamin D (25(OH)D >30 ng/mL) had the highest risk of fracture compared with African American women with the lowest level (25(OH)D <20 ng/mL).  Interestingly, no equally dramatic associations were seen in any other racial or ethnic group in the study.

The contrast was found to be similar in men of African descent and whites in another study. White men with greater vitamin D levels had fewer fractures while men of African descent with lower levels of vitamin D had fewer fractures.

Implications for adequate vitamin D and calcium levels

Historically, the levels of vitamin D that “ring alarm bells” for calcium metabolism have been derived from mathematical modeling^5-10 or by determining at what vitamin D level there is change in fracture risk.^11-14  However, newer studies suggest that the model may not hold true for African Americans. Combining all of the data, African Americans may not need as much calcium and vitamin D to maintain good bone health as other ethnic groups.

Calcium and vitamin D recommendations for African Americans

Calcium and vitamin D are still required for good bone health.  Until more research is published confirming optimal levels, African Americans should target intake of calcium from food and supplements in the 1,000–1,200 mg/day range and not exceed 1,800 mg/day.  Vitamin D intake of 600–800 IUs/day should be sufficient for African Americans to maintain optimal levels. The serum vitamin D target should be 20–30 ng/mL, as opposed to 40–60 ng/mL for whites.

References:

1. Aloia JF, Chen DG, Chen H. The 25(OH)D/PTH threshold in black women.  J Clin Endocrinol Metab 2010; 95:5069–5073.
2. Gutiérrez OM, Farwell WR, Kermah D, et al. Racial differences in the relationship between vitamin D, bone mineral density, and parathyroid hormone in the National Health and Nutrition Examination Survey.  Osteoporos Int 2011; 22:1745–1753.
3. Cauley JA, Danielson ME, Boudreau R, et al. Serum 25 hydroxyvitamin (OH)D and clinical fracture risk in a multiethnic Cohort of women: the women’s health initiative (WHI).  J Bone Miner Res 2011; 26(10):2378–2388.
4. Barbour KE, Zmuda JM, Horwitz MJ, Strotmeyer ES, Boudreau R, Evans RW, Ensrud KE, Gordon CL, Petit MA, Patrick AL, Cauley JA. The association of serum 25-hydroxyvitamin D with indicators of bone quality in men of Caucasian and African ancestry.  Osteo Int 2011; 22(9); 2475-2485
5. Bischoff-Ferrari HA, Giovannucci E, Willett WC, et al. Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr 2006; 84:18–28.
6. Chapuy MC, Preziosi P, Maamer M, et al. Prevalence of vitamin D insufficiency in an adult normal population.  Osteoporos Int 1997; 7:439–443.
7. Holick MF, Siris ES, Binkley N, et al.  Prevalence of Vitamin D inadequacy among postmenopausal North American women receiving osteoporosis therapy.  J Clin Endocrinol Metab 2005; 90:3215–3224.
8. Krall EA, Sahyoun N, Tannenbaum S, et al. Effect of vitamin D intake on seasonal variations in parathyroid hormone secretion in postmenopausal women.  N Engl J Med 1989; 321:1777–1783.
9. Malabanan A, Veronikis IE, Holick MF. Redefining vitamin D insufficiency.  Lancet 1998; 351:805–806.
10. Steingrimsdottir L, Gunnarsson O, Indridason OS, et al. Relationship between serum parathyroid hormone levels, vitamin D sufficiency, and calcium intake. JAMA 2005; 294:2336–2341.
11. Cauley JA, Lacroix AZ, Wu L, et al. Serum 25-hydroxyvitamin D concentrations and risk for hip fractures.  Ann Intern Med 2008; 149:242–250.
12. Cauley JA, Parimi N, Ensrud KE, et al. Serum25-hydroxyvitamin D and the risk of hip and nonspine fractures in older men.  J Bone Miner Res 2010; 25:545–553.
13. Cummings SR, Browner WS, Bauer D, et al. Endogenous hormones and the risk of hip and vertebral fractures among older women.  Study of Osteoporotic Fractures Research Group.  N Engl J Med 1998; 339:733–738.
14. Looker AC, Mussolino ME. Serum 25-hydroxyvitamin D and hip fracture risk in older U.S. white adults.  J Bone Miner Res 2008; 23:143–150.
15. Heaney RP. The importance of calcium intake for lifelong skeletal health.  Calcif Tissue Int 2002; 70:70–73.