Soybeans - an iron source?
levels of women who are marginally iron deficient, suggest US
researchers who have been studying iron bioavailability in
different varieties of the seed.
Some soybean varieties may be able to improve the nutritional levels of women who are marginally iron deficient, suggest US researchers who have been studying iron bioavailability in different varieties of the seed.
The research, published in this month's American Journal of Clinical Nutrition, claims that ferritin in soybeans is a highly usable source of the iron many women need, according to the US Agricultural Research Service which assisted with the research.
The finding could help combat iron deficiency, which afflicts 30 per cent of the world's population. The study counters the belief that iron from ferritin in soybeans has poor bioavailability and thus is not readily absorbed into the body once ingested.
In the study, 18 female volunteers - most of whom had marginal iron deficiency - showed iron absorption rates above those expected when they ate soybeans prepared as broth and muffins. They ate the muffins and had their iron measured 14 days later, then repeated the process with broth.
The absorption rate of iron in the study averaged 27 per cent, exceeding the 5 to 10 per cent expected, based on prior studies conducted with humans. It is believed that use of a soybean variety high in ferritin caused these elevated levels.
The authors, from Penn State University's General Clinical Research Center, conclude: "These results show that soybeans appear to be a good source of nutritional iron in marginally iron-deficient individuals. More study is needed on the effect of plant nodulation on the form of soybean iron, aimed at enhancing bioavailability to combat iron deficiency in at-risk populations."
Ross Welch, a plant physiologist with ARS' Plant, Soil and Nutrition Laboratory in Ithaca, New York, assisted by growing soybeans with a radioactive isotope of iron that made it possible to "label" the iron in seed ferritin, making it detectable in red blood cells.
Welch cautions that the results are not unequivocal because not all of the iron in the soybeans used was in the ferritin form. This is being addressed during the study's current phase.
