Acid Not Linked to Calcium Loss
I’ve been reviewing the scientific literature on protein and bone health. As many readers know, there has been a theory that animal protein, by way of increased sulfur amino acids, causes calcium excretion leading to osteoporosis. This theory was always on shaky ground and more recent evidence has contradicted the theory. I just read a meta-analysis on the subject and added the following to the article, Bones, Vitamin D, and Calcium, on VeganHealth.org:
“Another 2009 meta-analysis found that among five well-designed studies measuring calcium balance, net acid excretion was not associated with either decreased calcium balance or a marker of bone deterioration (48).”
The paper had an interesting list of cohort studies in the discussion:
“First, during 8 yr of follow-up, fracture risk was not reduced among a cohort of 36,217 postmenopausal women who consumed either lower protein or lower NAE [net acid excretion] diets (37). Second, wrist fracture risk was highest among 1865 peri- and postmenopausal women who consumed the lowest protein intakes over 25 yr of follow-up (38). As well, a recent 2-yr trial in 276 postmenopausal women either supplemented with potassium citrate (expected to neutralize the acid of the Western diet) or encouraged to consume increased fruit and vegetables showed that these interventions did not reduce bone turnover or decrease bone loss (36).”
The take home message, which I’ve written about before, is that not eating animal protein does not protect you from osteoporosis. Make sure you get enough calcium, vitamin D, and even (plant) protein.
36. Macdonald HM, Black AJ, Aucott L, Duthie G, Duthie S, Sandison R, Hardcastle AC, Lanham New SA, Fraser WD, Reid DM. Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial. Am J Clin Nutr. 2008 Aug;88(2):465-74. (Link) Free article available.
37. Dargent-Molina P, Sabia S, Touvier M, Kesse E, Bréart G, Clavel Chapelon F, Boutron-Ruault MC. Proteins, dietary acid load, and calcium and risk of postmenopausal fractures in the E3N French women prospective study. J Bone Miner Res. 2008 Dec;23(12):1915-22. (Link) Free article available.
38. Thorpe DL, Knutsen SF, Beeson WL, Rajaram S, Fraser GE. Effects of meat consumption and vegetarian diet on risk of wrist fracture over 25 years in a cohort of peri- and postmenopausal women. Public Health Nutr. 2008 Jun;11(6):564-72. Epub 2007 Aug 9. (Link) Free article available.
48. Fenton TR, Lyon AW, Eliasziw M, Tough SC, Hanley DA. Meta-analysis of the effect of the acid-ash hypothesis of osteoporosis on calcium balance. J Bone Miner Res. 2009 Nov;24(11):1835-40. (Link)