We have known for decades that fluoride helps build strong teeth, and that it contributes to bone health. A study recently published in the Archives of Internal Medicine adds to what scientists know of its benefits to bone.

A measure of strength

Researchers from the University of Texas recruited 85 women at least 65 years old. All were able to walk normally, but x-rays of their spines showed vertebrae compression, a sign of osteoporosis. The participants received either a daily dose of 25 mg sodium fluoride or an inactive sugar pill in 3 year-long cycles, with a 2-month period separating each cycle. In addition, all the women supplemented their diets with 945 mg calcium and 600 IU cholecalciferol (vitamin D). Bone mineral density was measured periodically throughout the 42-month trial, and the rate of fractures of the vertebrae was calculated.

The risk of spine fracture was reduced by 60% in the women who took sodium fluoride, compared with those who took the sugar pills. All participants, though, ended the study with greater spine bone density, a positive outcome likely due to their regular use of calcium and vitamin D supplements.

How fluoride fits in

Why the stronger bones? Most likely because bones are in a constant state of flux, or "remodeling." Cells called osteoblasts build up bone minerals, while cells called osteoclasts remove minerals from the skeleton for other uses within the body. Hormones, diet, and age affect this process. Fluoride helps keep bones strong by stimulating the osteoblasts. In combination with an adequate intake of calcium and vitamin D, it can help slow the erosion that leads to porous, brittle bones.

The long-term use of sodium fluoride, though, may have some drawbacks. It can cause an upset stomach, and some participants of earlier studies have complained of leg pain, which researchers suspect might result from bones weakened by excessive bone remodeling. However, neither side effect was a problem in the current study.

Prevention points

Osteoporosis is called the 'silent disease' because many people don't know they have it until they suffer a fracture. In women - who are hardest hit by the disease - estrogen helps preserve bone strength, so maintaining healthy bones becomes a particularly pressing problem after menopause. Therefore, doctors encourage women to get a bone mineral density test to detect osteoporosis before a fracture occurs.

While the use of sodium fluoride to prevent bone loss is still in the testing phase in the U.S., there are medications available that can help preserve bone density. But medication alone won't do it. A diet rich in calcium and vitamin D, and regular weight-bearing exercise should be part of everyone's osteoporosis prevention program.