Symbiotic Yogurt, Calcium Absorption and Bone Health in Young Adult Women

Overview

Prebiotics have been linked to increased calcium absorption in animal and human studies (particularly in adolescents and in premenopausal women). Similarly, probiotics have been found to benefit calcium homeostasis in pregnant women, and to promote bio-mineralization in animal models. The effect of symbiotic on calcium absorption has been tested in rats, but not in human studies. The primary objective of this study is to investigate the effect of daily consumption of a functional symbiotic yogurt containing inulin and Lactobacillus rhamnosus compared to a control yogurt, on calcium absorption in young adult women. A secondary objective is to relate changes in calcium absorption following yogurt consumption, with calcium metabolism, vitamin D status, bone mass, calcium intake and overall composition of habitual diet.

A potential strategy to reduce the risk of osteoporosis later in life is to promote optimal bone mass during early adulthood by including in the diet functional foods that maximize the efficiency of calcium absorption. This approach is specially important in women because of their greater risk for osteoporosis than men. In this study, we hypothesized that the daily consumption of a yogurt containing inulin and Lactobacillus rhamnosus (symbiotic yogurt) increases the efficiency of calcium absorption in young adult women when compared to daily consumption of a yogurt of similar composition but without prebiotic or probiotic (control yogurt). Subjects in this study will be randomly assigned to consume daily the symbiotic yogurt or the control yogurt during two 3-week periods with a wash-out period of 3-weeks, in a cross-over design. Calcium absorption will be measured by stable calcium isotope methodology. Bone mass (BMD, BMC) will be measured by dual-Y ray absorptiometry. Serum intact parathyroid hormone, 25-hydroxyvitamin D and dietary intake will be measured by conventional methods.