Effect of meal composition and phytate content on zinc absorption in humans from an extruded bran product

The effect of extrusion cooking of a high fibre cereal product on zinc absorption was studied using radioisotopic labelling of single meals and measurement of whole-body retention. Thirty-three subjects participated in the study. Three extruded products were tested containing 10 % gluten, 20 or 30 % wheat bran and 60 or 70 % starch and compared to the corresponding non-extruded ingredients. One additional product was extruded after reduction of the phytate content. The test products were served with a cooked meal or with milk as the main ingredient of a breakfast. When served with a cooked high protein meal there was no difference in Zn absorption from an extruded product or corresponding raw materials, 36·6±2·0% and 31·8±3·1% respectively. Zn absorption from a breakfast including 150 g of an extruded product was only 6·2±0·6%. However, Zn absorption was greatly improved when the extrusion was performed after reduction of the phytate content.