The effect of protein intake on bone density is still uncertain but research increasingly suggests that it may be more important than previously thought.
Researchers from the University of Western Australia in Perth and other Australian institutions used data from a cross-sectional and longitudinal study of a population-based sample of 1077 women aged around 75 years old.
At baseline, protein consumption was measured with a food-frequency questionnaire, and bone mass and structure were measured by using quantitative ultrasound of the heel.
One year later, hip bone mineral density (BMD) was measured by using dual-energy X-ray absorptiometry.
The results show a positive correlation between protein intake and qualitative ultrasound of the heel, as well as hip bone mineral density, even after adjusting for age, body mass index, and other nutrients, write the researchers in this month's issue of the American Journal of Clinical Nutrition (vol 81, no 6, pp1423-1428).
For those women with the lowest intake, (less than 66g of protein per day), ultrasound of the heel was 1.3 per cent higher than women with the highest intake (more than 87g protein per day) and hip BMD was 2.6 per cent more.
"These data suggest that protein intakes for elderly women above current recommendations may be necessary to optimize bone mass," note the authors.