Dietary lentils and calcium balance in adult men

Abstract

The effect of dietary lentils on calcium balance was evaluated in nine healthy male subjects. The Control and Experimental (+ 130 g dry lentils) diets were each fed for three weeks in a cross-over design. Study diets were matched to subjects' usual calcium and energy intakes, and balanced for protein and phytate. Complete fecal collections were made for all weeks and 24-hour urine collections were made in Week 3 of each period. Calcium balance was maintained during both the Control (0.4 ± 0.8 mmol/day, mean ± SEM) and Experimental periods (− 0.6 ± 0.9 mmol/day); fecal calcium remained unchanged (28.5 ± 1.7 mmol/day, 29.7 ± 1.5 mmol/day, respectively). Urinary excretion, however, varied from Control to Experimental periods for the following: calcium decreased from 5.43 ± 0.44 to 4.53 ± 0.41 mmol/day (P < 0.0001); sodium (Na) decreased from 149 ± 4 to 133 ± 3 mmol/day (P = 0.0003); potassium (K) increased from 90.8 ± 4.7 to 102.5 ± 3.1 mmol/day (P = 0.015), respectively. Changes in urinary K and Na reflected dietary intake levels. There was no change in net acid excretion. The decrease in renal calcium excretion may be due to a protective role of dietary K as well as a decrease in renal Na excretion, independent of changes in endogenous acid. This study shows that adding lentils to the diet, while maintaining a constant phytate intake, does not adversely affect calcium balance.