The typical midlife woman in the US consumes about 700 mg of calcium daily — far less than the recommended 1,200 mg for women age 50 and older. Perhaps this would improve if more women were aware of recent research showing how directly calcium’s ability to prevent bone loss translates into better health.

Until recently, there was scant evidence that calcium cut the risk for hip fracture, a common and disabling complication of thinning bones. As part of a large study called the Women’s Health Initiative (WHI), my colleagues and I conducted a seven-year clinical trial of calcium and vitamin D supplementation. More than 36,000 postmenopausal women were assigned to take either placebos or daily supplements of calcium at 1,000 mg plus vitamin D at 400 international units (IU), in two divided doses. Compared with placebo users, women who consistently took their pills as prescribed decreased their hip fracture risk by 30%… while in the 60-and-up age group, risk was reduced by 21% whether or not the pills were taken consistently. The benefit might have been even greater if higher doses of vitamin D had been tested — many experts now recommend 800 IU to 1,000 IU daily. Calcium also may protect against…

  • Colorectal polyps. Small trials of calcium supplementation report reductions in risk for precancerous polyps called colorectal ­adenomas. In the WHI, how­ever, calcium supplementation did not lower colorectal cancer risk. Research is ongoing.
  • Weight gain. Although the effect was modest, WHI participants assigned to calcium supplementation were less likely to gain weight. Theory: Calcium may positively affect fat metabolism.
  • The news about heart health: Although a recent small trial suggested that calcium supplements may contribute to cardiovascular problems, the much larger WHI study found that calcium plus vitamin D supplements did not increase heart attack or stroke risk.

    Good dietary sources of calcium are low-fat dairy foods… canned oily fish with bones (sardines, salmon)… calcium-fortified orange juice and cereals… broccoli, collard greens and kale.

    Few women get enough calcium from food alone. Best: Take a daily calcium supplement, preferably along with vitamin D to maximize absorption. Options: Calcium carbonate (Caltrate, Viactiv) requires stomach acid for proper absorption, so you must take it with a meal or snack… calcium citrate (Citracal) is more convenient because it can be taken without food, but you need a higher dose to get the same amount of actual (elemental) calcium.

    Excess calcium can increase kidney stone risk, impair kidney function and interfere with magnesium absorption. National guidelines: Do not exceed 2,500 mg of calcium daily from all sources. If you supplement with more than 500 mg, take it in divided doses at least two hours apart.