Many patients ask their healthcare providers whether they should take vitamins. Since the last Medical Letter article on this subject, more data have become available on the benefits and risks of taking vitamins.

Osteoporosis is characterized by low bone mass with microarchitectural disruption and skeletal fragility that results in an increased risk of fracture. The diagnosis has traditionally been established by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD (T score -2.5) or more below the mean are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of hip fracture based on clinical risk factors and BMD at the femoral neck.

Cataracts are the leading cause of blindness worldwide because cataract surgery is not available to most people in developing countries.

The results of a randomized, placebo-controlled trial of calcium and vitamin D supplements in more than 36,000 postmenopausal women, conducted as part of the Women’s Health Initiative (RD Jackson et al. N Engl J Med 2006; 354:669), have been misinterpreted by some patients to mean that they should stop taking such supplements.

At the time of recruitment, the participants in this study had an average daily calcium intake of 1100-1200 mg. They were randomized to take either 1000 mg of calcium carbonate plus 400 IU of vitamin D₃ or a placebo for an average of 7 years. Both groups were permitted to take calcium and vitamin D supplements on their own as well. In the intention-to-treat population, the study supplements increased hip bone density but did not decrease the incidence of hip fractures. The subgroup of women who adhered to the protocol and actually took the study supplements showed a significant reduction in hip fractures compared to the control group.

Men and women over age 50 should have a total calcium intake of about 1200 mg per day (Treat Guidel Med Lett 2005; 3:69). If they need a supplement to achieve that, calcium citrate is more expensive, but it offers some advantages over calcium carbonate: it can be taken without food, causes less GI disturbance and may be less likely to cause kidney stones.

With any calcium salt, vitamin D is necessary for optimal absorption. The recommended minimum daily requirement of vitamin D (vitamin D₃ is preferred) is 400 IU for people 50-70 years old and 600 IU for those over 70. But those infrequently exposed to the sun may need 800- 1000 IU of vitamin D daily, and many experts recommend 800 IU or more for all postmenopausal women.

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Coenzyme Q10, a fat-soluble antioxidant also known as ubidecarenone, ubiquinone and CoQ10, is marketed as a dietary supplement in the US, both as a single ingredient and in various combination products.

Chromium is marketed as a dietary supplement, usually containing 20-500 mcg of a chromium salt. It has been promoted for weight loss, muscle building, and for prevention and treatment of diabetes, among other claims. As a dietary supplement, chromium can be sold without proof of efficacy or safety.

Many drugs are now marketed for treatment of postmenopausal osteoporosis, but questions remain about their use.

A nasal spray formulation of cyanocobalamin (Nascobal – Questcor) has been approved by the FDA for maintenance treatment of vitamin B₁₂ deficiency. Nascobal is already available as an intranasal gel. Vitamin B₁₂ deficiency, diagnosed by elevated serum concentrations of methylmalonic acid with or without elevated serum homocysteine and low serum B₁₂ concentrations (<200 pg/mL), is common in older patients.1

Since intestinal absorption of B₁₂ may be impaired, the usual maintenance treatment of deficiency is intramuscular injection of the vitamin in doses of 1 mg every 4 weeks (after more frequent doses have restored serum concentrations to normal levels). However, in patients with atrophic gastritis and even in those with pernicious anemia, some oral cyanocobalamin (about 1%) is absorbed by diffusion.2 A randomized, controlled trial comparing oral to parenteral cyanocobalamin therapy in deficient patients found daily oral 2-mg doses of the vitamin as effective as monthly injections.3

No studies have been reported with the expensive new formulation. Medical surveillance is recommended, no matter what treatment is used, to document normalization of hematologic indices.

1. R Clarke et al. Prevention of vitamin B-12 deficiency in old age. Am J Clin Nutr 2001; 73:151.

2. FA Lederle. Oral cobalamin for pernicious anemia. Medicine’s best kept secret? JAMA 1991; 265:94.

3. AM Kuzminski et al. Effective treatment of cobalamin deficiency with oral cobalamin. Blood 1998; 4:1191.

Many patients ask their physicians whether they should take vitamins. Since the last Medical Letter article on this subject, more data have become available on the benefits and risks of taking vitamin supplements.

The pathogenesis of acne is multifactorial: follicular hyperkeratinization, Propionibacterium acnes bacteria, sebum production, androgens and inflammation have all been implicated. P. acnes, a gram-positive microaerophilic bacterium, plays an important role in the development of acne lesions by secreting chemotactic factors that attract leukocytes to the follicle, causing inflammation.

Patients may be asking about Airborne, a dietary supplement that is being heavily promoted for prevention and treatment of colds. It contains 7 herbal extracts, 3 vitamins, 2 amino acids, selenium, zinc and many other ingredients. Airborne Jr is available for children. There are some concerns. First, there is no conclusive evidence that this product or any of its ingredients prevents colds or shortens their duration. Second, the adult tablet contains 1 g of vitamin C, and the directions for use advise taking 1 tablet at the first sign of a cold and repeating the dose every 3 hours as necessary. Vitamin C in doses higher than 1 g increases oxalate and urate excretion and may cause kidney stones (EN Taylor et al, J Am Soc Nephrol 2004; 15:3225). Third, the safety of this herbal extraction combination has not been established. And with herbs and dietary supplements in general, we only have the manufacturers' word on the label for what's in them.

High doses of beta carotene, vitamin C, vitamin E and zinc oxide are now being promoted to the general public to "preserve eye health" (Ocuvite PreserVision), "promote retinal and visual health" (VisiVite) and "preserve healthy vision" (ICaps). Internet advertisements for these products all refer to a clinical trial, the Age-Related Eye Disease Study (AREDS), which was conducted in patients with age-related macular degeneration (AMD).