The effect of bicarbonate in mineral water on bone metabolism: interventional studies.

show an effect of Bicarbonate (Bic) in food and in mineral water, but not of an acid load, on bone metabolism in 4 controlled intervention trials. A) Basic food and Bic-rich mineral water were given to 8 male volunteers during 4 days, and then replaced by a control diet, equal in calories, protein, Na, and Calcium (Ca), in a randomized order after a washout period. The first diet decreased sign. urinary Ca excretion by 45%, and resorption markers (CTX/creat.) by 15 % (Buclin 2001). Therefore, short term nutritional alkali-load reduced bone resorption. B) An oral acid load of 6.4 g (120 mmol) NH4Cl per day for 2 days given to 8 volunteers, and compared to 120 nmol NaCl/day, lowered urin. pH by about 1 unit over the whole day compared to NaCl (p=0.0001), and slightly decreased blood pH and bicarbonate by about 2 mmol/l (p=0.002, resp.0.0001). But after 1 day it had no influence on markers of bone metabolism or on their response to Ca (Buclin 2003). C) Bic-rich mineral water in 20 healthy (Bic 2643 mg and Ca 378 mg /1.5 l) was given over 4 weeks to 10 young women on a free diet and compared with a Ca-rich water (Bic 605 mg, Ca 728 mg in 1.5l)(N=10). The Bic-rich water increased slightly urine pH (fasting and 24 hrs), and lowered sign.the resorption markers (urin. CTX/creat. in 24 hr urine) by 25 % (ANOVA p<0.05). The Ca-rich water increased only urinary Ca excretion by 31 % (Burckhardt). D) The effect in Calcium sufficiency: 30 young women on an equilibrated free diet were given 1.5 l per day of either a Ca-rich water (Bic 437 mg, Ca 780 mg /1.5 l) or of a water rich in both Ca and Bic (Bic 3258mg, Ca 821mg/1.5 l). While the Ca-water only had random effects on bone resorption, the Bic