Lactose malabsorption and intolerance and peak bone mass

Background & Aims: Lactose malabsorption per se is not associated with alterations of bone mineral density (BMD) or calcium intake, but when intolerance symptoms are present a lower calcium intake and reduction of BMD values are evident. The purpose of this study was to evaluate whether lactose intolerance interferes with the achievement of an adequate peak bone mass in young adults. Methods: Of 103 enrolled healthy subjects, 55 proved to be lactose malabsorbers with H-2 breath test after lactose administration, and 29 of them experienced intolerance symptoms (diarrhea, abdominal pain, bloating, flatulence). Lumbar and femoral BMD by dual-energy X-ray absorptiometry was measured, and calcium intake and biochemical indices of bone and mineral metabolism were evaluated. Results: Lumbar and femoral BMD, calcium intake, and mineral metabolism did not differ between malabsorbers and absorbers, although among malabsorbers, intolerant subjects showed significant alterations of all these parameters in comparison with tolerant subjects. A strict correlation was evident between BMD values and both severity of symptoms and calcium intake and between calcium intake and severity of symptoms. Conclusions: Lactose intolerance prevents the achievement of an adequate peak bone mass and may, therefore, predispose to severe osteoporosis.