Minerals

The possible changes in the mineral composition of food during frying could be the consequence of losses by leaching, or changes in concentrations cau sed by exchanges between the food and culinary fat of other compounds. The net result depends on the type of food, the frying fat used and the frying process. Moreover, the modifications that frying produces in other nutrient s could indirectly affect the availability of dietary minerals. The most ou tstanding ones are those that can take place in the fat or in the protein. With respect to the interactions between frying oils and minerals, we have recent knowledge concerning the effects of consuming vegetable oils used in repeated fryings of potatoes without turnover, on the nutritive utilizatio n of dietary minerals. The experiments have been carried out in pregnant an d growing rats, which consumed diets containing, as a sole source of fat, t he testing frying oils or unused oils. it seems that the consumption of Var ious frying oils, with a polar compound content lower or close to the maxim um limit of 25% accepted for human consumption, does not alter the absorpti on and metabolism of calcium, phosphorous, iron or copper. Magnesium absorp tion from diets containing frying oils tends to increase but the urinary ex cretion of this element increases, resulting imperceptible the variations i n the magnesium balance. The urinary excretion of Zn also increased althoug h its balance remained unchanged. Different studies referring to the effect s of consuming fried fatty fish on mineral bioavailability will also be pre sented. On one hand, frying can cause structural changes in fish protein, w hich are associated with an increase in iron absorption and a decrease in b ody zinc retention. The nutritive utilization of other elements such as mag nesium, calcium and copper seems to be unaffected. On the other hand; it ha s been described that an excess of fish far, acids in the diet produces iro n depletion, but when fatty fish is fried in olive oil the quality of the f ish oil improves, enhancing the nutritive utilization of iron and other die tary minerals.