Relationship between the calcium-to-protein ratio in milk and the urinary calcium excretion in healthy adults—a controlled crossover study

Abstract

Over the years, doubts have arisen concerning the use of milk as a calcium source in the prevention of osteoporosis, particularly because of potential offsetting effects of protein and phosphorus. Thus, a new milk product with a higher calcium content and lower contents of protein, phosphorus, and energy was developed. A controlled crossover study was done to determine the way in which substitution of the new milk product (860 mL) for normal milk (1000 mL) in the diet of healthy adults affected the urinary excretion of calcium and hydroxyproline. Short-term consumption of the product significantly lowered 24-h urinary calcium excretion by approximately 0.65 +/- 0.19 mmol/d (means +/- SEM, p less than 0.001). The ratio of fasting urinary hydroxyproline to creatinine did not decrease, indicating no significant reduction of bone resorption in our subjects. Elderly people in particular might benefit from the new product because it reduces their calcium loss as well as their intake of protein, phosphorus, energy, and liquid volume.