Calcium and Osteoporosis

Posted by Blog Sunday, March 6, 2011

Osteoporosis is a disease that involves loss of bone strength leading to an increased risk of fracture. It is well known to occur in postmenopausal women, but can also be present in other populations. Osteoporosis afflicts 25 million people in the United States, but there are no symptoms unless a bone is broken. Hip fracture in an older person is something to be avoided as it makes movement difficult and can be slow to heal.

Postmenopausal bone loss is mostly due to increases in bone loss, which are more important than decreases in bone formation. Osteoporosis is a long-term chronic disease that normally takes decades to develop. Proper nutrition is one of the important factors in preventing osteoporosis. Supplemental calcium cannot prevent or heal osteoporosis by itself. Widely varying levels of calcium intake around the world are not associated with corresponding levels of osteoporosis. It is an unexplained paradox that osteoporosis is  much more prevalent in affluent cultures with high calcium intakes than it is in poorer cultures with low calcium intakes.

High levels of calcium intake and high levels of vitamin D are helpful in slowing the progression of bone loss. Loss of calcium from the bones, as can occur on a day with lower calcium intake coupled with high sodium and protein intake, is hard to replace. Calcium can be removed quickly from bones, but it is a slower process to rebuild bones. As is true with many chronic diseases, prevention is the best approach.

One of the unavoidable risk factors is age, as bones tend to lose strength as we age. One way to decrease risk is to stay flexible and balanced, which lowers the likelihood of a fall. Weight-bearing exercise is important in early life, as it increases bone density. Exercise and movement in later life also stimulate bone formation to offset bone resorption. Some people have genetically denser bones than others, which lowers risk.

Recommended Levels of Calcium
The Food and Nutrition Board of the Institute of Medicine has set Adequate Intake levels (AI) for calcium. An RDA was not set because of the many factors that interact to affect bone health. As noted above, extra sodium and protein change the amount of calcium needed in the diet. If vitamin D is inadequate for long periods of time, lower levels of circulating calcidiol (the precursor form of vitamin D) may limit calcium absorption. Bone formation also requires vitamin K, vitamin A, magnesium, and potassium. Additionally, weight-bearing exercise helps strengthen bones.

The Food and Nutrition Board has set the AI levels high enough to compensate for extra protein, extra sodium, and low levels of vitamin D. Please refer to Table 9-1 for adequate intake levels for calcium. With lower sodium and protein levels, with regular weight-bearing exercise, and with adequate vitamin D from sun exposure, less calcium is needed to ensure bone health. Upper intake levels for calcium have been set at 2500 mg daily for ages one and above.

More about Calcium:


Bone Remodeling

Calcium and Muscle Contraction

How Calcium Is Regulated in the Blood

Deficiency of Calcium

Calcium and Osteoporosis

Food Sources of Calcium

Calcium Supplements

Calcium Toxicity


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