You probably associate calcium with strong bones, and you may be aware that vitamin D is sometimes called the "sunshine vitamin." What you might not realize is that these two nutrients, one a vitamin and the other a mineral, interact inside your body in important ways. If you're not getting enough vitamin D, your calcium count may suffer as well.
Vitamin D
Vitamin D is called the sunshine vitamin because your skin can synthesize it when exposed to the UVB radiation of the sun. This form of vitamin D is known as D-3, or cholecalciferol. Some factors, such as skin color, age and fat malabsorption syndromes, influence your ability to synthesize vitamin D from sunlight. In such cases, dietary sources of vitamin D can make up for the shortfall. According to the Linus Pauling Institute Micronutrient Information Center, foods that provide vitamin D include salmon, sardines, fish liver oils, eggs and fortified foods, such as milk, cereals and breads. Vitamin D deficiency can result in rickets, osteomalacia and muscle weakness and pain.
Calcium
Calcium is the most abundant mineral in your body. Most of it is found in your teeth and bones, but about 1 percent circulates in your blood or is found in your soft tissues. Your bones are built, broken down and rebuilt on a cellular level throughout your life, according to the Linus Pauling Institute. When rate of bone breaking down exceeds the rate of rebuilding, as can occur with age, osteoporosis can result. If your blood calcium levels fall too low, your body will steal calcium from your bones to bring it back to normal levels. For this reason, a steady supply of calcium is crucial for maintaining healthy bones.
Relationship Between Calcium and Vitamin D
Vitamin D plays a critical role in keeping blood calcium levels steady. Even if you are obtaining enough dietary calcium, you risk osteoporosis if you're deficient in vitamin D. Vitamin D promotes the intestinal absorption of calcium from the foods you eat. Vitamin D also regulates the reabsorption of calcium from bone. When your blood levels of calcium fall, your parathyroid glands release hormones that increase the production of vitamin D, which results in increased intestinal calcium absorption, increases reabsorption of calcium that had been filtered by your kidneys and removes calcium from bone to normalize serum calcium levels.
Daily Requirements
According to nonprofit information resource HelpGuide.org, the recommended daily dosage of calcium for adults between the age of 19 and 50 is 1,000 mg. Once you're past age 50, consume 1,200 mg of calcium daily. The recommended dosage for vitamin D is between 1,000 and 2,000 IU daily.
References
- Linus Pauling Institute at Oregon State University; Calcium; Jane Higdon, et al.; October 2007
- Linus Pauling Institute; Vitamin D; Jane HIgdon et al.; January 2008
- HelpGuide.org; Calcium and Your Bones; Maya W. Paul, et al.; April 2010
- Dummies.com; Building Up and Breaking Down: Your Bones Day by Day; Carolyn Riester O'Connor, et al.
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