Calcium retention unaffected by high-protein diet
effects on women's ability to retain calcium, according to a study
by US researchers.
A high-protein diet containing mostly meat does not have adverse effects on women's ability to retain calcium, according to a study .
About 200 million people worldwide are believed to be affected by the bone thinning known as osteoporosis. The US Agricultural Research Service (ARS), the chief scientific research agency of the US Department of Agriculture, explains how in recent years, scientists have theorised that high-protein diets leach calcium from bones, leading to bone loss, based on findings from tests involving purified proteins. But now they have discovered that unlike purified proteins, meat contains substantial amounts of potassium and phosphorus, which reduce urinary calcium loss.
ARS researchers Zamzam Roughead and Janet Hunt at the Grand Forks Human Nutrition Research Center controlled the diets of 15 healthy postmenopausal women, providing both low- and high-meat diets for eight weeks each. The women consumed about 600 milligrams (mg) of calcium per day, half the recommended intake of 1,200 mg. Calcium, sodium and caffeine intakes were kept constant.
After the first four weeks of each eight-week phase, the scientists tracked calcium levels using body count technology that detects differences in calcium retention and excretion. The scientists found that even with low-but-average calcium intake, the volunteers could eat twice the recommended dietary allowance of protein, mostly as meat, and not have an adverse effect on calcium retention or on biomarkers for bone breakdown.
The high-meat diet consisted of 20 per cent of daily calories as protein, or about 117 grams, including 10.5 ounces of meat. The low-meat diet consisted of 12 per cent protein, including 1.5 ounces of meat. The scientists commented that while eating as much as 35 per cent of daily calories as protein is considered safe, the study was designed to give no more than 20 per cent of daily calories as protein to ensure that volunteers consumed a varied diet.
The study was published in the April issue of the Journal of Nutrition.