Guar delays intestinal calcium absorption in man.

The effect of guar on the absorption of the calcium isotope 45Ca was measured in six normal subjects. Values for the delay before the initial rise of radioactivity in plasma (delta t) and the initial fractional absorption rate (alpha) were derived using a non-linear curve-fitting computer programme. Guar significantly reduced the fraction of 45Ca absorbed between 15 and 120 min. Guar increased the delay before the initial rise of radioactivity in plasma and reduced the initial fractional absorption rate. The results show that a dietary fibre which does not bind calcium in vitro reduces the rate of calcium absorption in man.