Calcium is a mineral of concern in many developmental stages of life, especially during periods of rapid growth such as growth spurs and pregnancy. Inadequate calcium intake puts an individual at risk of developing osteoporosis, a debilitating disease that increases the risk of bone fracture and mortality in late adulthood. Consuming calcium-rich foods and calcium supplements can help counteract bone loss as a result of aging and reduce the risk of osteoporosis.
Calcium Absorption From Foods
The absorption of calcium from foods is relatively low, at approximately 30 percent, according the Office of Dietary Supplements, or ODS. Absorption varies with age. Infants and young children who depend on calcium for rapid bone growth can absorb up to 60 percent of dietary calcium, while adults, whose bones are only remodeling instead of growing, can absorb 15 to 20 percent. As you age, you absorb even less calcium. The Institute of Medicine, or IOM, sets the recommended calcium intake for adults age 70 and older at 200 mg higher than adults younger than 70 to compensate for age-related decreases in calcium absorption.
Calcium Absorption From Supplements
Calcium supplementation is a convenient and effective means of increasing calcium intake. The absorption of calcium increases with the amount of elemental calcium contained in the supplements. But your body cannot absorb more than 500 mg of elemental calcium at a time. If you are taking a calcium tablet with more than 500 mg of elemental calcium, split the pill into two to three doses and take them throughout the day to increase absorption. Taking your last calcium dose before bed might stop bone loss at night, according to Washington University.
Dietary Factors That Reduce Calcium Absorption
Many dietary factors can reduce how much calcium gets absorbed. Organic acids such as phytic acid and oxalic acid bind to calcium and inhibit its absorption. Spinach, for example, contains high levels of oxalic acid. Eating spinach with milk reduces the amount of calcium absorbed from milk. Other foods that have high oxalic acid content include sweet potatoes, beans and collard greens. Phytic acid is present in beans, seeds, nuts, whole grains and soy isolates. In particular, wheat bran is a known inhibitor of calcium absorption. Alcohol and caffeine also can weaken your ability to absorb calcium.
Dietary Factors That Increase Calcium Absorption
Vitamin D helps with calcium absorption. Because vitamin D hangs around in your body longer, you do not need to supplement vitamin D as frequently as calcium, according to Washington University. The IOM recommends 600 IU of vitamin D a day from ages 1 to 70. Regular exposure to sunshine without sunscreen is an effective method of getting enough vitamin D. Just 5 to 30 minutes of sun exposure to arms, legs, face or back between 10 a.m. and 3 p.m. twice a week provides adequate vitamin D. If you are taking calcium carbonate, one of the most common calcium supplements, a glass of orange juice can help increase absorption.
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