Calcium, Vitamin D, and Bone Health.

Date:

16-Nov-2005

Source

JAMA

Related Monographs

Consumer Data: Calcium Vitamin D Arthritis, Osteo
Professional Data: Calcium Vitamin D Arthritis, Osteo

Article

Calcium is the most abundant mineral in the human body. Average healthy males have about two and a half to three pounds of calcium while females have about two pounds. Approximately 99 percent of calcium is present in the bones and teeth, which leaves only about one percent in cells and body fluids. While the most important function of calcium involves the maintenance of skeletal health, the small percentage of calcium outside the bones is used to maintain a variety of vital body functions.

Vitamin D is known as the "sunshine" vitamin because it is formed in the body by the action of the sun's ultraviolet rays on the skin. The fat-soluble vitamin is converted in the kidneys to the hormone calcitrol, which is actually the most active form of vitamin D. The effects of this hormone are targeted at the intestines and bones.

A recent study published in the Journal of the American Medical Association examined the role of both vitamin D and calcium in relation to bone health. Researchers wanted to understand the necessity of high calcium intake in relation to vitamin D status by measuring parathyroid hormone levels. This study was conducted in Iceland and involved 2,310 healthy adults that were separated into 3 age groups. Using a food frequency questionnaire, these groups were then divided based on calcium intake and serum vitamin D levels. A total of 944 participants completed this study. The results showed that those with a lower serum level of vitamin D and an intake of less than 800mg of calcium, also had a higher parathyroid hormone level. The authors concluded that, “As long as vitamin D status is ensured, calcium intake levels of more than 800 mg/d may be unnecessary for maintaining calcium metabolism. Vitamin D supplements are necessary for adequate vitamin D status in northern climates.”1

References

1. Steingrimsdottir L. Relationship Between Serum Parathyroid Hormone Levels, Vitamin D Sufficiency, and Calcium Intake. Jama. Nov 2005: 294:2336-2341.