High-protein diets, such as the Atkins plan, have been controversial, since studies have shown that they can cause bone loss. Yet elderly people are supposed to eat more protein, to help wound healing and maintain muscle mass.
"Our results suggest that a higher calcium intake is going to be protective against any adverse effects of protein on bone, and may allow protein to have a positive effect," says lead author Bess Dawson-Hughes, MD, senior scientist and chief of the Calcium and Bone Metabolism Laboratory at Tufts University.
The 342 men and women over age 65 each took either a 500 mg calcium-and-vitamin-D supplement or a placebo daily. During the three-year study, researchers kept track of the volunteers' diets, specifically their calcium and protein intake and bone mineral density.
The supplement group -- particularly those who ate a diet high in protein -- had significantly better bone mass density -- an accurate measure of bone loss. Those who took the placebo, however, had less calcium absorbed into their bloodstream when they consumed more protein.
Whether protein comes from a vegetable or animal source did not make a difference, but the amount did count, researchers say.
The recommended protein intake for a healthy person is between 40-60 grams per day, although the study volunteers had an average protein intake of 79 grams per day.
As for calcium, dietitians recommend 1,200 mg of calcium per day for people over 50, which is readily available in one 500 mg supplement, one cup of fat-free milk, one 8 oz. serving of yogurt, and a 1 oz. slice of cheese. -->