Doctors who encourage women to take calcium supplements to prevent brittle bones in middle age may be missing the point.
A new study on the individual differences in the way women absorb calcium suggests that it is the fat to fibre ratio in a woman's diet, not calcium supplementation, that is most important.
Researchers at Columbia University, New York, studied the calcium absorption of 142 healthy pre and perimenopausal women. They found that the common advice to eat a low fat diet might actually prevent calcium from being absorbed.
In this study, the average amount of calcium absorbed was around 35 per cent of that ingested, with a range of 17 to 58 per cent. Greater calcium absorption was positively associated with a higher fat intake in the diet aswell as body mass index, and serum concentrations of vitamin D and parathyroid hormone. Poor absorption did not depend on how much or how little calcium was ingested. Instead, poor absorption was related to a higher fibre diet, alcohol consumption, physical activity and symptoms of constipation.
Women approaching the menopause are often advised to switch to a low fat diet to remain healthy. Yet, the results of this study suggest that inflexible and stringent measures to reduce fat intake may be doing more harm than good.
The authors suggest that public health recommendations for a low fat, high fibre diet need reassessing to prevent not just bone disorders, but other chronic conditions, such as hypertension and colon cancer, in which calcium may have a protective role (Am J Clin Nutr, 2000; 71: 466-71).