Potential effects of low calcium intake on body composition, muscle function, and appetite

Low calcium intake is associated with a higher risk of accumulating excess body fat. This could be explained by its effect on the components of energy balance, particularly on lipid balance. Lipid metabolism is influenced by inadequate calcium intake that leads to an increase in parathyroid hormone (PTH), a consequent mobilization of calcium in bone, and kidney reabsorption of the mineral. In the gut, calcium contributes to the formation of insoluble lipid soaps, which promote intestinal fat loss. There is also growing evidence in humans and animals suggesting the existence of a calcium-specific appetite control mechanism where low-calcium diets may promote an increase in food intake to compensate for calcium inadequate intake. Paradoxically, these adaptations to regulate calcemia are also accompanied by an accumulation of calcium in soft tissues. In adipocytes, intracellular calcium favours an increase in lipogenesis relative to lipolysis, which may explain a decrease in whole-body fat oxidation. This effect is also seen in skeletal muscle cells where the functioning of mitochondria is impaired by an intracellular calcium overload. There is suggestive evidence that this effect results in a decrease of aerobic capacity, muscle strength, and endurance. As described in this paper, an increase in dietary or supplementary calcium intake seems to be adequate to mitigate the negative effects of low calcium intake without impacting other components of body homeostasis.