Early research published in the Beta Beta Beta Biological Society in 2004, suggested that when dietary tannin is increased, excess iron should theoretically not be absorbed.
Instead, iron binds with tannins and is excreted by the body.
“To our knowledge, this is the first clinical case indicating that blue raisins decrease the absorption of iron from foods,” concluded the authors of the case report.
“Although our observation comprises a rare cause of iron-deficiency anaemia, natural bioactive polyphenols may offer an adjunct dietetic treatment in patients with hereditary hemochromatosis, who experience iron overload because of an accelerated rate of intestinal iron absorption.”
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