Calcium and Vitamin D
Many published studies have demonstrated that low calcium intake is associated with low bone mass and increased fracture risk. It has been suggested that calcium deficiencies in youth can account for a 5-10% difference in peak bone mass and can significantly increase the risk for hip fracture in later life.
Among postmenopausal women, studies have shown that supplemental calcium can decrease the rate of bone loss from the femoral neck, the spine and the total body. Women who have been postmenopausal for six or more years tend to reap a greater benefit from calcium supplementation than those who are within five years of menopause. Since calcium is a nutrient, not a drug, the positive effects of supplemental calcium are most pronounced among women with low to moderate calcium intakes. Recent clinical trials have suggested that supplementation with calcium or calcium plus vitamin D, can reduce fracture incidence by about 30-50% in subjects with low calcium intakes.
Vitamin D deficiency is also a concern in bone health. The nutrient is essential for calcium absorption and normal bone mineralization. Studies have shown that low levels of vitamin D can contribute to low bone density. Recent evidence suggests that deficiencies in this nutrient may additionally contribute to hip fractures in postmenopausal women.
Protein and Bone Health
It is known that high protein intake increases the calcium requirement. However, the association between protein and osteoporotic bone fractures in individuals has not been fully explored.
Reduced protein intake has been linked to low femoral neck bone density in elderly hospitalized patients. In these individuals, clinical outcomes following hip fracture were significantly enhanced when protein intake was normalized through nutritional supplementation.
Soy and Isoflavones
The soybean plant, a legume, contains specific phytochemicals known as isoflavones. Phytochemicals are non-nutritive substances, in that they contain no vitamins or minerals. Isoflavones are also phytoestrogens. Phytoestrogens are compounds that have mild estrogenic effects.
Chick peas and legumes are good sources of isoflavones. The legume, soy, has the greatest concentration of these chemicals.
Isoflavones have received a good deal of attention for their possible cancer and heart disease-preventive traits. Because of their estrogen-like properties, many believe that isoflavones and other phytoestrogens may one day play a role in postmenopausal health.
One isoflavone derivative, ipriflavone, is currently used outside of the United States as an osteoporosis therapy. Ipriflavone has had a bone-protective effect in several studies. Further research is needed to understand the systemic effects of this compound before it can be considered a therapeutic approach for osteoporosis prevention and treatment.
Nutrition and Weight
Nutritional status and body weight are additional considerations in skeletal health. Nutritional status can influence one's tendency to fall and is a factor in the maintenance of adequate soft tissue mass to protect the bones from a fall-related fracture. Of particular concern are thin, undernourished, elderly individuals who may lack sufficient muscle and fat mass in the hip region.
Body weight, is an important determinant of bone density. The skeleton of heavy individuals tends to benefit from it's increased load-carrying role. Studies have demonstrated that body weight is positively correlated with bone mineral density, and that weight loss is associated with bone loss. (Increasing calcium intake appears to reduce the bone loss that accompanies weight loss.)
Weight loss in older individuals has been linked to an increase in fracture risk. Researchers found that "extreme" weight loss (10% or more) beginning at age fifty, increased the risk of hip fracture in older women and men. Conversely, a weight gain of 10% or more decreased hip fracture risk. Such studies suggest that maintaining weight in later life may have a protective effect on bone
Related Resources
Source: NIH ORBD ~ NRC, Nutrition and the Skeleton, 8/2001
