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Educate your patients on the importance of 3-A-Day of Dairy: Here's
a great
tool (PDF: 618k) to show families how to get their 3-A-Day of Dairy
every day for stronger bones.
Developed in conjunction with The American Academy of Family
Physicians, The American Academy of Pediatrics, The American Dietetic
Association, and The National Medical Association.
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Dairy Council Digest Archives
Dietary Protein & Bone Health: New Perspectives
Protein's Effect on Calcium Metabolism
Over the years, high protein intake has been cited as a risk factor for osteoporosis. Studies have repeatedly shown that intake of protein, particularly purified proteins from either animal or plant sources, increases urinary calcium excretion (7,12,15,16).
Some researchers speculate that any protein-induced urinary calcium loss would result from increased bone resorption, which would compromise bone health if not matched by an increase in bone formation (16). It has been proposed that dietary protein, especially from animal sources rich in sulfur amino acids, increases endogenous acid production, which is buffered by alkaline salts of calcium from the skeleton (11,12,16). Reliance on bone to balance protein-induced endogenous acid could increase bone loss and risk of osteoporosis. However, as discussed below, the majority of epidemiological studies fail to show that a high protein intake adversely affects bone health.
Several factors such as the protein source, other dietary components, and the duration of protein consumption may influence protein's calciuric effect (11). In studies using purified proteins (e.g., casein), hypercalciuria is induced, whereas this effect is not consistently shown with common food sources of protein (e.g., milk, meat) (17-20). Spencer et al. (17), in a series of human metabolic studies, showed that meat or milk protein did not affect calcium excretion, a finding attributed to the phosphorus content of these commonly consumed complex protein sources. However, endogenous fecal calcium loss, which has been shown to increase with phosphate intake, was not measured (19). As such, these early studies could not rule out a possible negative effect of protein on calcium balance (19).
Protein's calciuric effect may be a short-term response. A recent study in postmenopausal women found that a high protein intake from food (meat) resulted in an initial high renal acid excretion that was not maintained, indicating adaptation (20). In this study, the high protein intake did not adversely affect calcium retention or bone metabolism (20). The researchers noted that, in contrast to meat as a source of protein, earlier studies showed no adaptation in renal acid excretion or hypercalciuria with increased intake of isolated protein sources after 75 to 95 days (20).
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