SEATTLE—Data from a longitudinal study suggest a higher protein intake does not have an adverse effect on bone in premenopausal women; and cross-sectional analyses suggest low vegetable protein intake is associated with lower bone mineral density (BMD) (Am J Clin Nutr. 2010;91(5):1311-16). A total of 560 females aged 14 to 40 years were examined for cross-sectional and longitudinal associations between baseline dietary protein (animal or vegetable) and BMD. Dietary protein intake was assessed by using a semi-quantitative food-frequency questionnaire in participants.
The mean (±SD) protein intake at baseline was 15.5 ± 3.2 percent. After multivariable adjustment, the mean BMD was similar across each tertile of protein intake. In cross-sectional analyses, low vegetable protein intake was associated with a lower BMD. For every percentage increase in the percentage of energy from protein, no significant longitudinal changes in BMD were observed at any anatomic site over the follow-up period.