Revisiting lactose as an enhancer of calcium absorption

Lactose has been recognized as an enhancer of calcium absorption in mammals. The stimulating effect of lactose on calcium absorption is apparent in animal studies, but in humans such an effect is still controversial. When glucose or galactose was chosen as a control sugar, the effect of lactose on the enhancement of calcium absorption was not significant (P > 0.05). However, when compared with other types of non-absorbable sugars, lactose did have a positive (P < 0.05) effect on calcium absorption in humans. Subjects with lactose intolerance showed greater absorption of calcium (P < 0.05) compared with those with lactose tolerance once lactose was consumed as a dairy component. Unhydrolyzed lactose appears to be utilized as a prebiotic to support the growth of health-promoting gut flora, which is recognized as an enhancer of calcium absorption. Thus, both hydrolyzed and unhydrolyzed forms of lactose appear to be positively involved in enhancing calcium absorption in mammals.