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More Evidence of Low Vitamin D in People Taking Antiretrovirals
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12th European AIDS Conference, November 11-13, 2009, Cologne, Germany
Mark Mascolini
A 102-patient report from an HIV clinic in Bolzano, Italy [1] adds to the data suggesting a high rate of vitamin D deficiency in people with HIV [2]. Low vitamin D quotients threaten HIV-infected people not only because D plays a critical role in bone metabolism, but also--perhaps--because of recently uncovered interactions between vitamin D and the immune system.
Oswald Moling and colleagues at Bolzano's General Hospital observed that, without vitamin D, only 10% to 15% of dietary calcium is absorbed, and only about 60% of phosphorus [3]. Yet 25-hydroxyvitamin (25(OH)D) levels often go unreported in studies of hypophosphatemia and bone deficits in people with HIV. Protease inhibitors can impair activation of vitamin D to 1,25-dihydroxyvitamin D [4], and some evidence suggests efavirenz increases vitamin D inactivation and thereby contributes to vitamin D deficiency and osteomalacia [5,6].
Circulating 25(OH)D levels are considered the best indicator of vitamin D status [2]. Moling and coworkers repeatedly measured 25(OH)D in 102 consecutive patients in the winter and spring. Everyone lived in the Alpine area of northern Italy and was taking antiretroviral therapy. Vitamin D levels dip in winter, when exposure to sunlight it lower.
Only 18 of these 102 people (18%) had vitamin D quotients matching the recommended level of at least 30 ng/mL (75 nmol/L). Four of the 18 with stout vitamin D readings had spent their holidays in a tropical country. Thirty-six people (35%) had levels below 10 ng/mL (25 nmol/L).
Eighteen people (18%) had hypophosphatemia (phosphorus below 2.5 mg/dL or 0.8 mmol/L). Seventeen of these 18 also had low vitamin D concentrations. People with low vitamin D took 1400 to 2000 IU of 25(OH)D daily or 10,000 to 14,000 IU once weekly to regain healthy levels. Only 40 of 84 people (48%) with a first vitamin D reading below 30 ng/mL regained a normal level through supplementation.
This study is limited because there is no comparison group of people without HIV from the same region. But unlike some other studies in people with HIV, it measured vitamin D over time and gauged the impact of supplementation.
The investigators believe research is showing that vitamin D is "not only a predictor of bone health but is also an independent predictor of risk reduction for infection, autoimmune, cardiovascular, psychiatric diseases, and cancer" [7,8].
Reviewing vitamin D readings in HIV studies, Harvard's Eduardo Villamor notes that low D levels have been found in some but not all groups [2]. Limitations of these studies, Villamor writes, "preclude the exclusion of vitamin D deficiency as a potentially serious problem among HIV-infected individuals, particularly in populations with limited exposure to sunlight for cultural or geographical reasons."
References
1. Moling O, Passler W, Rimenti G, Pagani L, Vedovelli C, Mian P. Low vitamin D blood levels in 102 consecutive individuals taking antiretroviral therapy. 12th European AIDS Conference. November 11-13, 2009. Cologne, Germany. Abstract PE9.7/2.
2. Villamor E. A potential role for vitamin D on HIV infection? Nutr Rev. 2006;64(5 Pt 1):226-233.
3. Buchacz K, Brooks JT, Tong T, et al. Evaluation of hypophosphataemia in tenofovir disoproxil fumarate (TDF)-exposed and TDF-unexposed HIV-infected out-patients receiving highly active antiretroviral therapy. HIV Med. 2006;7:451-456.
4. Cozzolino M, Vidal M, Arcidiacono MV, et al. AIDS. 2003:17:513-520.
5. Gyllensten K, Josephson F, Lidman K, Sääf M. Severe vitamin D deficiency diagnosed after introduction of antiretroviral therapy including efavirenz in a patient living at latitude 59 degrees N. AIDS. 2006;20:1906-1907.
6. Herzmann C, Arasteh K. Efavirenz-induced osteomalacia. HIV-protease inhibitors impair vitamin D bioactivation to 1,25-dihydroxyvitamin D. AIDS. 2009;23:274-275.
7. Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357:266-281.
8. Tavera-Mendoza LE, White JH. Cell defenses and the sunshine vitamin. Sci Am. 2007;297:62-65,68-70,72.
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