Vitamin D has been shown in several studies to be important for bone health. Vitamin D is essential for absorption of calcium and for depositing calcium in the bones.
With an increase in our aging population, bone fractures in older age have become a very common, serious, and costly health problem. By the age of 90, one in every three women and one in every six men will have experienced a hip fracture. The healthcare costs add up to about $10 billion a year. Clearly it is important to take preventive steps to build strong bones and prevent fractures.
Researchers at Harvard University and other medical centers wanted to see how effective vitamin D supplements might be in preventing fractures in the elderly. They conducted a "meta-study" (a study that combined the results of five large, random, controlled trials already conducted) including more than 6,000 people who were followed for several years. The people in the studies were randomly divided into two groups: those who took vitamin D daily, and those who took a placebo.
Researchers found that those who took 700 to 800 IU per day of vitamin D daily reduced their risk of hip and non-spinal fractures by 25 percent. Reducing one out of every four fractures by simply taking a vitamin D supplement is a very cost-effective intervention. The researchers estimated that one hip fracture is prevented for every 45 elderly people who take vitamin D daily. One non-spinal fracture is prevented for every 27 persons taking a vitamin D supplement daily.
In this study, people who took calcium (along with vitamin D or by itself) received no additional benefit when it came to a decrease in fractures. People who took only 400 IU of vitamin D daily also did not show any particular bone-health benefit. It seems that 700 to 800 IU is what's needed to get a measurable decrease in fracture rate.
How Does Vitamin D Help?
Many studies have shown that vitamin D decreases mineral loss in the bones of older people by improving calcium absorption and utilization. Vitamin D also appears to have a beneficial effect on muscle strength and balance. One study, looking at this issue, found that vitamin D supplements were responsible for decreasing the incidence of falls by 22 percent. Another review including several studies showed that vitamin D decreased falls by 35 percent. In all of these studies, this benefit result in fewer fractures.
Conflicting Data?
Two other large British studies that looked at the benefits of vitamin D consumption found no decrease in fracture rates from taking either vitamin D or extra calcium (1,000 mg per day). Both of these studies, however, were conducted only on high-risk people. One study included only those who had had a fracture recently and were trying to prevent secondary fractures.
Conclusions
Simply taking high doses of calcium doesn't appear to have measurable benefits for the elderly (age 70 and older) who are at high risk for fractures. It's possible that the people in the study were already getting adequate levels of calcium and vitamin D, and that adding more wouldn't help.
The review of multiple studies did show, however, that taking 700 to 800 IU of vitamin D daily was significantly beneficial in reducing fracture rates. Getting adequate calcium and vitamin D are both essential for building healthy bones in young people. It is especially important for young girls before the age of 21. As for adding extra calcium to the diet in old age – it simply might be too little too late to cause a noticable benefit. |
