When low stomach acid levels are linked to osteoporosis, it is assumed to be the result of reduced calcium absorption. However as mentioned above, calcium uptake under low acid conditions is either normal, or even on the high side, with calcium becoming bio-unavailable and potentially resulting in reduced bone density and calcification outside of bone unless sufficient acidifying co-factors are present. In contrast, manganese and iron absorption are reduced under low stomach acid conditions, or with high magnesium or calcium levels:... Full Text