Impact of Milk and Yogurt Supplementation on Bone Health, Body Composition, and Gut Microbiota in Canadian Young Adults

Milk and dairy products contain significant amounts of nutrients that contribute to optimal health - nutrients like calcium, vitamin D, and high-quality protein. Fermented milk products or fermented dairy products are dairy foods that have been fermented with certain bacteria. Yogurt is a fermented dairy product containing millions of beneficial bacteria. In this study, the invesgitagtors will look at the effect of milk (a non-fermented dairy product) and yogurt (a fermented dairy product) supplementation on bone health and the amount of fat and muscle mass in Canadian young adults over a 24-month period. While dairy products contain significant amounts of nutrients, the scientific community does not know the impact of long-term supplementation of fermented (i.e., yogurt) or non-fermented (i.e., milk) dairy food on bone health and the amount of fat and muscle mass in young adults. To fill this knowledge gap, the investigators will recruit participants with low calcium intake and assign them to three different groups: 1) milk (intervention) group; 2) yogurt (intervention) group; and 3) control group. The investigators will ask the participants in the milk group to drink 1.5 servings (375 mL) of milk per day for 24 months. Participants in the yogurt group will consume 2 servings (350 g) of yogurt per day for 24 months. Those in the control group will continue their usual diets. Using a randomized controlled trial design, the investigators will measure bone health parameters, hormonal indices related to bone metabolism, body composition (e.g., muscle mass, fat mass), and the number and composition of bacteria living in the gastrointestinal (GI) tract. The hypothesis is that supplementation with yogurt will have more positive effects on bone health indices, particularly femoral neck BMD as the primary outcome, than milk in Canadian adults aged 19-30 years. The secondary hypothesis is that supplementation with yogurt, as a fermented milk product, will have a more benefic