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Vitamin D Deficiency & Broken Bones

Dec 2, 2010 | By Ruben J. Rucoba
Vitamin D Deficiency & Broken Bones
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Vitamin D has long been known to be important for bone health, especially in the prevention of rickets, a serious disease that causes bone malformation and poor growth in children. But recent data suggest it is also important in the prevention of fractures in both the young and the old.

Vitamin D

We get vitamin D from sunlight, from food that has vitamin D added to it, or from supplements. Vitamin D-3, also known as cholecalciferol, is the most common form of vitamin D but is inactive in the body. It undergoes two changes or hydroxylations in the body. The first change occurs in the liver to make 25-hydroxy vitamin D, or calcidiol. The second change is in the kidney to make 1,25-dihydroxy vitamin D, or calcitriol. Calcitirol is a potent steroid hormone, and is the active form of vitamin D in the body.

Effects

Calcitriol promotes calcium absorption in the gut, and helps maintain adequate blood levels of calcium and phosphorus, all of which are important for strong bones. Low levels of vitamin D leads to thin, brittle or misshapen bones.

U.S. Evidence

There have been literally dozens of scientific studies examining the link between vitamin D and fractures, but the results have been conflicting. However, two recent studies have clarified the situation. A study published in the Archives of Internal Medicine in 2009 reported the results of a meta-analysis, which is a sophisticated review that pools the data from many studies. This particular meta-analysis looked at over 20 different studies that included over 82,000 patients. The results were striking: adequate vitamin D greatly reduced the risk of nonvertebral fractures, or fractures in places other than the spinal column, such as hips or legs. This risk was lowered by as much as 29 percent, but this risk reduction was not seen in those who took less than 400 IU daily.

European and U.S. Evidence

A meta-analysis of seven studies that included 68,500 patients published in the "British Medical Journal" in 2010 concluded that vitamin D alone did not reduce the incidence of fractures, even when given at doses of 400 to 800 IU daily. But when vitamin D and calcium were given together, there was a reduction in all fractures, including hip fractures and vertebral fractures.

At-risk Groups

Some groups are at high risk of vitamin D deficiency and fractures: the elderly, babies who are exclusively breast fed, patients with kidney or liver failure, people with malabsorption problems like cystic fibrosis, and people who don't get much sun exposure to their skin. When measuring vitamin D levels, the best test is the level of 25-hydroxy vitamin D, often written as 25 (OH) vitamin D. Levels of 25- hydroxy vitamin D should be higher than 30 ng/ml to prevent vitamin D deficiency.

Treatment

For those with documented vitamin D deficiency, treatment doses may be as high as 1,000 IU of vitamin D-3 per day, or 50,000 IU of vitamin D-2 every two weeks. Some patients even need 100,000 IU of D-3 once every three months. At these levels, a prescription for vitamin D is needed. Your physician will need to closely monitor levels of 25-hydroxy vitamin D to ensure that toxic levels are not reached.

Prevention

For those who do not have vitamin D deficiency but want to prevent it, supplementation with 600 to 800 IU daily is recommended. Calcium supplementation is recommended as well, but it varies by age, from 200 mg daily for infants less than 6 months old, to 1,300 mg daily for pregnant women and breastfeeding mothers. The November 2010 recommendations for vitamin D and calcium intake from the Food and Nutrition Board of the Institute of Medicine suggest a higher intake of vitamin D than previous recommendations.

References

Article reviewed by Tina Boyle Last updated on: Dec 2, 2010

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