Water fluoridation may benefit bones

Source: Tufts University
November 7, 2000 (Reviewed: February 2, 2003)

Introduction

Few nutrients evoke as much controversy as fluoride. Many people regard community water fluoridation as an effective way to combat tooth decay. Others consider it to be unwarranted and unwelcome mass medication. Well-designed studies have consistently demonstrated benefit and consistently failed to find it harmful. Most scientists now agree that fluoride inhibits and even reverses dental cavities. Fluoride's effect on bone mass is less certain. To clarify this issue, US researchers conducted a large study that compared bone strength and fractures in women who lived in an area where the water was fluoridated at some time during the past 20 years of their lives. Their findings are published in a recent issue of the British Medical Journal.

Over 7,000 women ages 65 and older, from throughout the US provided investigators with every address at which they had lived and their water source (public water supply, spring, or well) for the past 20 years. The researchers used water system records and the fluoridation census to categorize the women according to whether or not they had received fluoridated water. Bone density, an indicator of bone strength, was measured at the study's start and each volunteer was monitored for fractures every four months for seven years.

The researchers found that bone density and fracture patterns differed, depending on the women's water source. Those who lived in a community with fluoridated water had greater bone mass in the spine and femur (the large bone in the thigh) compared to the women who did not have access to a fluoridated water supply. Denser bones are less susceptible to fractures; these women had about 30% less spine and hip fractures. Interestingly, fluoridation did not protect against wrist fractures. Those women who had fluoridated water actually had thinner forearm bones than the women living in non-fluoridated areas.

Fluoride without fluoridation. Is it possible?

Osteoporosis, the thinning of bones that eventually leads to fractures, is a growing public health concern in the US and Europe. Although fluoride is typically associated with dental care and is routinely added to some community water supplies in over 60 countries to prevent cavities, this mineral is of current interest because of its unique ability to stimulate new bone formation. People who do not reside in areas that fluoridate their water supply ingest some fluoride from dental products, tea, and food and beverages processed in areas that do fluoridate. Still, their intake is usually only one-third to one-half that of those who live in communities that add fluoride to public water systems.

Fluoride supplements are usually suggested only for children living in areas without fluoridated water. Too much can have undesirable effects on teeth. Fluorosis, a discoloring of the teeth, is common in areas where the fluoride content of the water is naturally high. The effect of excess fluoride on bones is unknown. This study adds evidence that water fluoridation at current levels is not harmful to bones and may even be beneficial. But, it is not likely to become the primary defense against osteoporosis.

Maximizing bone health: fluoride is only one part of the equation

Individuals seeking to reduce their risk of osteoporosis should aim for adequate calcium from low-fat dairy products and leafy green vegetables. Vitamin D, which is manufactured in the skin on contact with sunlight, is also necessary for strong bones. About 20 to 30 minutes of sun exposure several times each week can help insure a sufficient supply of this nutrient. Vitamin D is also added to milk, except condensed milk, and to some fortified cereals in the US. Strong bones also benefit from regular weight bearing activities like walking or dancing.

Source

• Community water fluoridation, bone mineral density, and fractures: prospective study of effects in older women. KR. Phipps, ES. Orwoll, JD. Mason,  et al., British Medical Journal., 2000, vol. 321, pp. 860--864

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