Preventing fracture: more evidence against vitamin supplements

Most of the time when we talk about treating or preventing osteoporosis, we focus on building bone, whether it's by taking calcium and Vitamin D supplements or by building stronger bones through weight-bearing exercise. What we don't discuss nearly as often are those risk factors for osteoporosis that have little or nothing to do with the bone mass you created during youth and early adulthood.

One of these, and a fairly common one, is known as hyperhomocysteinemia, or high homocysteine levels in the blood. Homocysteine is an amino acid that is a byproduct of eating meat, and some research suggests that high blood levels of homocysteine are related to increased risk of heart disease. It has also been linked to increased risk of bone fractures due to osteoporosis. Homocysteine levels typically increase with age and are usually higher in men than women, making reducing homocysteine levels a possible treatment for osteoporosis.

Taking Vitamin B-12 (cobalamin) and folic acid reduces homocysteine levels - so would taking these supplements also reduce the risk of fractures due to osteoporosis? A team of scientists in the Netherlands recruited nearly 3,000 men and women over the age of 65 to participate in a 2-year study comparing taking a daily supplement of Vitamin B-12 and folic acid with taking a placebo (Am J Clin Nutr 2014;100(6):1578-86). The participants were required to be living outside a nursing home (although some at-home assistance was acceptable), have diagnosed high homocysteine levels, not be bedridden or permanently in a wheelchair, and without a cancer diagnosis for the 5 years prior to the start of the study.

After the 2-year study, the researchers compared the number of osteoporotic fractures experienced by those receiving the Vitamin B-12 and folic acid supplement (52 persons and 61 fractures) with those who received the placebo (61 persons with 75 fractures). After taking into account age, sex, starting homocysteine levels, and genotype, the researchers concluded that overall, there was no significant difference in risk of fracture between those who received the supplement and those who did not.

What they did notice, however, was that 62 persons receiving the supplement were diagnosed with cancer, while only 42 persons receiving the placebo developed cancer. Further analysis that excluded relapses in previous diagnoses of cancer still showed a significantly greater risk of all types of cancer, especially gastrointestinal and colorectal cancers.

What this means for you

While analyzing the participants according to age showed a slight decrease in risk of fracture among those participants under the age of 80, the increased risk of cancer outweighs the benefit. The researchers note that their study was not designed to test whether Vitamin B-12 and folic acid supplementation increased the risk of cancer, so this study should only be taken as an indication that more study is needed. The take-home message here should be that this study further supports the idea that you're better off eating your vitamins and minerals and not taking supplements. Good sources of B-12 include beef liver, shellfish, fresh tuna or salmon, and cereals and milk that have been fortified with B-12. Sources of folic acid include fortified cereals and breadstuffs, green leafy vegetables (especially asparagus and broccoli), and fruits.

First posted: December 3, 2014