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Nutrition Column

Nutrition & Exercise in the Prevention of Osteoporosis

After many years of research, a guaranteed method for the prevention of osteoporosis is yet to be found. Osteoporosis is a dangerous disease that sneaks up on millions of people around the world. The disease has no obvious overt symptoms but puts those affected at a high risk of wrist, spinal vertebrae, and hip fragility fractures. Bones begin to deteriorate and lose vital minerals and architecture. Although osteoporosis affects men and women, postmenopausal women are at greatest risk due to the decrease in estrogen production. The current World Health Organizationís definition of the disease is based on bone mineral content (BMC) or bone mineral density (BMD), but researchers are still debating proper diagnosis of the disease because BMC and BMD are strongly influenced by body size and there is still no solid evidence of these measurements associated with fracture risk. Along with genetics and aging, there are many modifiable risk factors associated with osteoporosis including nutrition, diet, and exercise. Many studies have been dedicated to identifying the proper combination of nutrition and exercise that can prevent the development of this disease. A study from Public Health Nutrition summarized the current knowledge on using diet and nutrition in the prevention of osteoporosis.

Since calcium is a necessary bone-forming mineral, it has been assumed that recommended consumption of calcium can increase bone mineral density and potentially prevent osteoporosis. The results from multiple studies looking at the effects of calcium supplementation on BMD, have shown NO significant relationship between calcium intake and the risk of fragility fractures. In studies conducted by the Department of Health, the New England Journal of Medicine, and the Journal of Bone and Mineral Research, calcium supplementation of women within 5 years of the menopause had no effect on the BMD of main regions of the skeleton at the greatest risk of bone loss at the time. It has also been shown that the countries with the lowest calcium intake like Africa and Hong Kong, have the lowest rates of hip fractures, and the countries with the highest calcium intake have the highest rates of fractures. Therefore it is misleading to inform people that appropriate calcium intake can prevent bone mineral loss.

Another nutrient thought to be essential for healthy bones is vitamin D, which is obtained from the diet or synthesized in the skin after exposure to sunlight. Vitamin deficiency has been linked to age-related bone loss and fragility fractures, but like calcium, supplementation with vitamin D has not shown significant effect on osteoporosis. Many health professionals use a combination of calcium and vitamin D supplementation as the minimum treatment for osteoporosis in postmenopausal women. In the recent large scale study, the MRC RECORD study, published in The Lancet, the effects of combined calcium and vitamin D supplementation on secondary prevention of fractures was investigated. The authors concluded that combined supplementation did not decrease the risk of another low-trauma fracture in an elderly population.

Much of the latest research points to a low-sodium, low animal protein, plant-based diet for bone health, just like for heart health. As for activity, researchers point to the benefits of weight-bearing exercise in terms of strengthening bones and stimulating calcium mineralization.

Exercise and staying physically active is highly recommended for maintaining healthy bones post menopause. However, elderly people may have difficulty exercising due to their current physical status, and exercise can also put people at risk for falling and being injured. With that in mind, several companies have developed vertical vibration devices that provide low magnitude, high frequency mechanical stimuli to increase the strength of bones. A study published in Journal of Bone and Mineral Research reported a 2.73% improvement in BMD was found after a one year intervention, which identifies a new noninvasive method of improving bone strength and preventing osteoporosis.

Diet and exercise do play key roles in bone health, but not in the way many of us think. Swimming, dairy, and calcium supplementation are not the way to go. Rather opt for a low-sodium, plant-based diet and activities that involve impact and force you to work against gravity.

Written by Jodie Sasaki with Eric Sternlicht, Ph.D. Occidental College, Los Angeles.