Women who are postmenopausal, pregnant or nursing, or athletes are more likely to need sufficient or additional calcium.

Postmenopausal women

Menopause leads to bone loss because decreases in estrogen cause:

• Bone resorption (breakdown) to overtake the building of new bone
• Decreases in calcium absorption

Annual decreases in bone mass of 3–5 percent per year frequently occur in the first years of menopause according to the National Institutes of Health. Increased calcium intakes during menopause do not completely offset this bone loss.

Hormone replacement therapy (HRT) with estrogen and progesterone helps increase calcium levels and absorption which can help prevent osteoporosis and fractures. In addition, consuming adequate amounts of calcium in the diet might help slow the rate of bone loss in all women.

Amenorrheic women and the female athlete triad

Amenorrhea is the condition in which menstrual periods stop or fail to initiate in women of childbearing age. This results from reduced circulating estrogen levels that decrease calcium levels.

Female athlete triad is a combination of three conditions: disordered eating, amenorrhea, and osteoporosis. Some females who play sports or exercise intensely are at risk of developing this problem. A female athlete can have one, two, or all three parts of the triad.

Exercise-induced amenorrhea generally results in decreased bone mass. In female athletes and active women, low bone-mineral density, menstrual irregularities, certain dietary patterns, and a history of prior stress fractures are associated with an increased risk of future stress fractures.

Such women need to consume adequate amounts of calcium and vitamin D. Getting enough of these nutrients can help reduce the risk of stress fractures and injuries.

Women and Osteoporosis

Females are at higher risk of developing osteoporosis and broken bones. Here are some facts from the National Osteoporosis Foundation:

• Of the estimated 10 million Americans with osteoporosis, about eight million or 80% are women.
• Approximately one in two women over age 50 will break a bone because of osteoporosis.
• A woman’s risk of breaking a hip is equal to her combined risk of breast, uterine and ovarian cancer.

There are a few reasons women are more likely to get osteoporosis than men, including:

• Women tend to have smaller, thinner bones.
• Estrogen, a hormone in women that protects bones, decreases sharply when women reach menopause, which can cause bone loss.