Polyphenols in Sorghum and Iron Absorption

Iron deficiency and iron deficiency anemia are two major public health problems in developing countries. In these countries, the use of monotonous plant-based diets, low in animal source food but high in iron absorption inhibitors such as phytic acid or polyphenol, lead to poor iron status or aggravate poor iron status caused by infections. In many West African countries sorghum is a major source of energy, protein, vitamins and minerals especially for the most poverty-stricken people. Some sorghum varieties are known to contain high levels of polyphenols which have an inhibitory effect on iron absorption in humans. Polyphenols are a huge group of plant metabolites with varying chemical structures. Depending on their structure, the level of complex formation with iron in the intestine and thus the negative effect on iron absorption is different.

Micronutrient deficiency can be combated by fortification of plant-based staples. Fortification is a promising food-based approach which can be applied when other strategies fail to provide adequate levels of the respective micronutrient in the diet. To fortify foods with iron, a wide variety of different iron compounds have been used. The iron compound sodium iron ethylenediaminetetraacetic (NaFeEDTA) overcomes the inhibitory effect of phytate on human iron absorption. No information about the potential enhancing effect of NaFeEDTA in presence of polyphenol is available.

The aims of the study are to investigate the effect of different sorghum polyphenol concentrations on human iron absorption and to investigate if the negative impact of the polyphenols can be overcome by using NaFeEDTA as iron compound. The study will include 32 apparently healthy young women which will consume sorghum porridges with different polyphenol levels and sorghum porridges fortified with ferrous sulfate as compared to NaFeEDTA. Furthermore test meals with added vitamin C or added laccase will be compared to a control meal. Iron absorption will be determined by stable isotope technique.