The effect of cooking method upon iron and zinc bioavailability in rice.

摘要

Prevention of iron deficiency rather than treatment is preferred by most nutritionists. The presence of a maximal iron supply is not advised because an excessive or unnecessary iron supplement may have biologically adverse effects, such as impaired immune resistance or negative interaction with other trace elements.;The goal of this study is to determine the bioavailability of iron and zinc in traditional Iranian rice dishes and to assess the effect of traditional methods of cooking rice upon iron and zinc bioavailability.;Iranian migrants residing in Sydney were surveyed in order to determine their food habits and traditional cooking methods, for the assessment of their effects upon the bioavailability of iron and zinc in Iranian rice dishes. Rice contains phytate, which is a potent inhibitor of iron absorption. The amount of phytate in rice depends on whether the rice is polished or not. The pre-cooking treatment such as soaking can also influence the phytate content of the rice. Soaking prior to cooking also reduced the amount of ion and zinc. The inhibitory effect of phytate is also overcome by adding different herbs, vegetables and legumes used traditionally in rice dishes cooked by Iranians. Herbs or vegetables such as coriander, parsley and cauliflower, used in Iranian rice dishes, increased the bioavailability iron and zinc. Results obtained from this research show that method of cooking, as well as the food mixture, is very important for the absorption of iron and zinc from the diet.;All cereals and most vegetables contain phytate (inositol hexaphosphate) which can bind iron and zinc and reduce their biological availability. The amount of iron available for absorption in any given diet depends to a large extent on the composition of the diet, e.g., the presence of vitamin C and haem iron, and the absence of phytate. Rice is one of the most important staples in the Iranian diet and, in fact, rice, for most Iranians, is not a side dish but a main dish to which other foods or ingredients are added. An awareness of the effects of cooking method on nutrient content is important because cooking techniques influence the overall quality of a group's diet.