The most plentiful mineral in the body is calcium. This mineral is necessary for the development of a healthy skeleton in childhood and the prevention of bone loss later in adulthood.

Calcium is involved in various functions:

• Formation of bones and teeth
• Muscle contractions
• Blood clotting

Because many factors affect calcium absorption, the most effective way to ensure adequacy is to increase calcium intake. On average, adults absorb about 30 percent of the calcium they ingest. The stomach’s acidity helps keep calcium soluble, and vitamin D helps make the calcium-binding protein needed for absorption. Whenever calcium is needed, the body increases its calcium absorption.

The recommendation of calcium for adolescents to the age of 18 years is 1300 milligrams daily. Adults aged 19 to 50 need 1000 mg of calcium a day. For women older than 50 and all adults older than 70, recommendations are raised again to 1200 milligrams a day.

Significant sources of calcium include:

• Milk and milk products
• Small fish (with bones)
• Leafy greens (bok choy, broccoli, chard, kale)

Calcium Deficiency Symptoms: Stunted growth in children; bone loss (osteoporosis) in adults.

Calcium Toxicity Symptoms: Constipation; increased risk of urinary stone formation and kidney dysfunction; interference with absorption of other minerals.