Fe and Zn bioavailability from red (merlot) and white (great northern) bean‐based (Phaseolus vulgaris) diets fed to anemic young pigs

Abstract

Beans contribute significant amounts of Fe in the diets of many populations. A major cause of Fe deficiency is poor Fe bioavailability from plant ‐ based diets containing Fe absorption inhibitors such as polyphenols. Our objective was to compare Fe and Zn bioavailability between red and white beans which differ in their polyphenol content.Anemic piglets at age 4 wks were allocated into 2 treatment groups (n=10) and fed corn/bean rations containing either 37% white or 37% red beans. Diets had no supplemental Fe. Pigs were given a meal containing intrinsically labeled (58Fe, 70Zn) beans followed by an intravenous (i.v.) injection of 54Fe and 67Zn on day 7 and again on day 21 of the experiment to assess Fe and Zn absorption. Blood samples were taken periodically. On day 35, animals were killed and duodenal sections were collected for DMT1 gene expression analysis. Fe absorption was calculated from 58Fe concentrations incorporated in hemoglobin. Zn absorption was calculated from the ratios of 70Zn to 67Zn in plasma. Fe absorption was 14% and 16% from the 1st meal and 9% and 10.5% from the 2nd meal for the white and red beans, respectively (P>.05). Zn absorption was 34% and 30% from the 1st meal (P>.05) and 28% and 37% from the 2nd meal (P<.05) for the white and red beans, respectively. DMT1 gene expression did not differ between treatments. These results show that Fe and Zn bioavailability from red/white bean‐based meals is similar.