Contents

Building better bones

There are several nutrients and activities that can help improve bone health and bone mineral density. In this issue of TreatmentUpdate, we underscore some of these.

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Calcium

In general, adults need between 1,000 and 1,200 mg per day of calcium. To find out more about getting calcium from your diet, see the following CATIE resources:

CATIE’s Practical Guide to Nutrition (see the chapter called “Managing the Effects of HIV and Meds on the Body”)

CATIE’s Positive Side magazine has these two informative articles:

Vitamin D

Many studies have found that HIV-positive people have either a deficiency or less-than-ideal levels of this vitamin in their blood. Factors such as liver and kidney disease can also play a role in depleting vitamin D. Some medicines and herbs used by HIV-positive people can also reduce vitamin D levels, including the following:

  • antibiotics – rifampin (rifampicin) and isoniazid, commonly used to treat TB. Vitamin D levels can sometimes fall after as little as two weeks’ exposure to these drugs.
  • anti-seizure drugs – phenobarbital, carbamazepine, phenytoin, valproic acid
  • anti-cancer drugs – Taxol and related compounds
  • antifungal agents – clotrimazole and ketoconazole
  • anti-inflammatory drugs – corticosteroids
  • anti-HIV drugs – emerging research suggests that the drugs efavirenz (Sustiva, Stocrin and in Atripla) and AZT (Retrovir, zidovudine and in Combivir and Trizivir) may reduce vitamin D levels in some people. In contrast, exposure to darunavir (Prezista) appears to raise vitamin D levels. Researchers continue to study the possible effects of different medications on vitamin D levels, so expect more news about this in the years ahead.
  • herbs – St. John’s wort or its extracts (hypericin, hyperforin)

A deficiency of vitamin D causes the body to produce excessive levels of parathyroid hormone (PHT), which may over the long-term cause bone thinning.

Medically guided supplementation of vitamin D is necessary to raise levels in the blood to at least 75 nmol/litre (30 ng/ml). This may mean that some people, particularly those with severe vitamin D deficiency, may require daily doses prescribed by their physician that range between 2,000 and 5,000 IU (international units) of vitamin D3. For further information about vitamin D dosing and safety issues, see TreatmentUpdate 185.

Exercise

Athletes generally tend to have greater bone mineral density than non-athletes. This suggests that physical exercise is useful for building bone density. Indeed, this is the case in adolescents whose skeletons are still growing. In adults, physical exercise helps to prevent further bone loss and among some HIV-negative people may even increase bone density by 1% or 2%. Before starting an exercise program, speak to your doctor to find out what kind of exercise is right for you.

Note that exercise (aerobic and resistance training), extra calcium and vitamin D are not enough to significantly reverse osteoporosis in HIV-positive people. There are drugs that are specifically designed to strengthen bone density and reverse osteoporosis. The most commonly used drugs to help people with osteoporosis are called bisphosphonates and we discuss these later in this issue.

— Sean R. Hosein

REFERENCES:

  1. Lindsay R, Cosman F. Chapter 354. Osteoporosis. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson JL, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 18th ed. New York: McGraw-Hill; 2012.
  2. Holick MF, Binkley NC, Hike A, et al. Evaluation, treatment and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism. 2011 Jul;96(7):1911-30.
  3. Bleicher K, Cumming RG, Naganathan V, et al. Lifestyle factors, medications, and disease influence bone mineral density in older men: findings from the CHAMP study. Osteoporosis International. 2011 Sep;22(9):2421-37.
  4. Yong MK, Elliott JH, Woolley IJ, et al. Low CD4 count is associated with an increased risk of fragility fracture in HIV-infected patients. Journal of Acquired Immune Deficiency Syndromes. 2011 Jul 1;57(3):205-10.
  5. Langsetmo L, Hitchcock CL, Kingwell EJ, et al. Physical activity, body mass index and bone mineral density—associations in a prospective population-based cohort of women and men: the Canadian Multicentre Osteoporosis Study (CaMos). Bone. 2012 Jan;50(1):401-8.
  6. Havens PL, Stephensen CB, Hazra R, et al. Vitamin D3 decreases parathyroid hormone in HIV-infected youth being treated with tenofovir: a randomized, placebo-controlled trial. Clinical Infectious Diseases. 2012 Apr;54(7):1013-1025.
  7. Diamond T, Wong YK, Golombick T. Effect of oral cholecalciferol 2,000 versus 5,000 IU on serum vitamin D, PTH, bone and muscle strength in patients with vitamin D deficiency. Osteoporosis International. 2012; in press.
  8. Fox J, Peters B, Prakash M, et al. Improvement in vitamin D deficiency following antiretroviral regime change: Results from the MONET trial. AIDS Research and Human Retroviruses. 2011 Jan;27(1):29-34.