Effect of soluble or partly soluble dietary fibres supplementation on absorption and balance of calcium, magnesium, iron and zinc in healthy young men

Objectives: This study is aimed at investigating the effect of feeding a soluble or partly soluble fibre rich-diet on the apparent absorption and balance of calcium, magnesium, iron and zinc in healthy young men, by using a chemical balance technique. Study design: Nine healthy young men were given a control diet or the same diet complemented with either inulin (soluble) or sugar beet fibre (partly soluble) during 28 d periods according to a 3 x 3 latin square design with three repetitions. During the 20 d adaptation period to fibre ingestion, experimental fibres were incorporated into bread (60%) and liquid foods (40%) up to a maximum of 40 g/d. Ca, Mg, Fe and Zn were measured in diets and in a 8 d urine and faecal composites to assess mineral absorption and balance. Results: The dietary mineral intake provided (mg/d) 859 +/- 196 of Ca; 311 +/- 43 of Mg; 11.6 +/- 1.7 of Fe; and 11.1 +/- 1.6 of Zn from the control diet. The apparent absorption of minerals from the control diet was (%) Ca: 21.3 +/- 12.5; Mg: 46.3 +/- 10.9; Fe: 21.8 +/- 12.3 and Zn: 14.0 +/- 14.5 (mean +/- s.d.). Ingestion of inulin significantly increased the apparent absorption and the balance of Ca. Sugar beet fibre ingestion resulted in a significant increase in Ca intake and balance, without modification its apparent absorption. Apparent absorption and balance of Mg, Fe and Zn were not significantly altered by the ingestion of either experimental fibre. Conclusions: Addition of the two experimental fibres (inulin or sugar beet fibre) to normal mixed diets can improve Ca balance without adverse effects on other mineral retention.