Cooking using moderate heat and for short time periods as well as cooking closer to meal times can help increase bioavailability. The latter means the extent to which nutrients can be used by the body.
That tip is contained in the 2013 Food and Agriculture Organisation report which is themed “Food Systems for Better Nutrition.”
The basic point that the report makes with regard to this issue is that the ways in which households process, preserve and cook food contribute significantly to micronutrient intakes. The said activities affect the bioavailability of some key micronutrients and the report cites as examples, germination and malting which can improve the bioavailability of iron by a factor of 8ÔÇô12.
“Soaking grains and legumes, a fairly typical household practice, can remove anti-nutrients that inhibit iron absorption,” it says.
In Malawi, soaking maize flour used for maize porridge fed to rural preschoolers was found to enhance the absorption of micronutrients. A long-term study in that country has shown that a range of traditional strategies combined with promotion of micronutrient-rich foods resulted in improvements in both haemoglobin and lean body mass and a lower incidence of common infections.
The report says that traditional food preservation techniques used in the home, such as sun-drying, canning and pickling of fruits and vegetables can enhance the bioavailability of micronutrients and preserve surplus micronutrient-rich foods for year-round use.
As important are the methods of cooking that are used in the home. In addition to those already mentioned, cooking green leafy vegetables with mild heat can increase the bioavailability of heat-sensitive nutrients such as vitamin C. The report quotes a study that showed that the use of appropriate quantities of fat or oil in stir frying or similar methods can also increase micronutrient bioavailability. This is due to the fact that oils facilitate absorption of certain nutrients.
However, traditional processes can be time-consuming and labour-intensive and some such processes can result in decreased micronutrient availability. One study showed that soaking legumes does not have a beneficial influence on the bioaccessibility of zinc.