| Summary: | <p>Nutritional recommendations encourage the Canadian
population to increase its intake of complex
carbohydrates with a resulting increase in dietary
fibre. Diets high in insoluble fibre are thought to
compromise calcium status by increasing faecal calcium
excretion. Calcium status is of particular concern due
to the risk of osteoporosis.</p>
<p>A six week study was conducted to determine the
effect of Laird lentil fibre and starch on calcium
balance. In a randomized experimental design, ten
males (19-37 years) consumed a control diet for three
weeks and the control diet plus 130 g lentils providing
13 g NSP; 80% insoluble, for three weeks. Seven-day
food records were used to adjust the study diet to the
subjects' usual calcium and energy intakes. Ultra-pure
water was consumed throughout the study. Duplicate
diets of food consumed were prepared. Radio-opaque
markers were given and complete faecal collections were
made. Twenty-four hour urine collections were made in
weeks three and six. Tablets containing PABA were
given to validate the completeness of urine
collections.</p>
<p>Lentils increased faecal weight (control 130.6 ±
11.8 g/d (Mean ± SEM); lentil 189.6 ± 21.2 g/d (P = 0.027). Calcium balance was maintained during both the
control (0.4 ± 0.8 mmol/d) and lentil periods (- 0.6 ±
0.9 mmol/d) (P = 0.503). Faecal calcium remained
unchanged (28.5 ± 1.7 mmol/d; 29.7 ± 1.5 mmol/d) (P =
0.434). Urine calcium decreased from 5.43 ± 0.44
mmol/d to 4.53 ± 0.41 mmol/d (P = 0.0001). Possible
mechanisms which may explain the change in renal
calcium excretion are changes in dietary calcium,
urinary sodium excretion, net acid excretion or renal
potassium excretion. Dietary calcium did not
significantly change (34.4 ± 1.8 mmol/d; 33.6 ± 1.9
mmol/d) (P = 0.095). Renal sodium excretion decreased
(149 ± 4 mmol/d; 133 ± 3 mmol/d;) (P = 0.0003). Renal
net acid excretion remained unchanged (49.2 ± 4.2
mmol/d; 52.3 ± 3.1 mmol/d) (P = 0.24). Renal potassium
excretion increased (90.8 ± 4.7 mmol/d; 102.5 ± 3.1
mmol/d) (P = 0.015).</p>
<p>This study shows that adding Laird lentils to the
diet does not adversely affect calcium status. The
significant decrease in renal calcium excretion may be
due to a combination effect from the changes in dietary
phosphorus, renal sodium and potassium with the change
in renal potassium excretion demonstrating the greatest
effect. Also, the resistant starch present in Laird
lentils may have had an effect on renal calcium
excretion.</p>
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