|TAN, SIOW YING|
|YEUNG, CHI KONG|
Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2008
Publication Date: 6/11/2008
Citation: Tan, S., Yeung, C., Glahn, R.P., Welch, R.M., Lei, X., Miller, D.D. 2008. Iron bioavailability to piglets from red and white common beans (Phaseolus vulgaris L.). Journal of Agriculture and Food Chemistry. 56(13):5008-14.
Interpretive Summary: More than 50% of the world’s population is deficient in iron as a result of low levels of available iron in staple food crops such as beans. Ways need to be found to increase the available amounts of iron in these foods. Polyphenols are known to inhibit the absorption of iron from diets. We studied the amount of absorbable iron in two types of common beans, red and white. These beans differed greatly in their concentrations of polyphenols with the red beans containing much higher levels of polyphenols compared to the white beans. The results of the experiment show that both the red and white beans contain about the same amount of absorbable iron (from 26% to 56% depending on when the iron absorption was determined) when fed to piglets for a period of 4 weeks. These results suggest that pigs can adapt to high levels of the polyphenols in beans possibly by increasing their secretion of protective proline-rich proteins in their saliva when fed a diet high in polyphenols.
Technical Abstract: Polyphenols in foods may chelate dietary Fe and lower its bioavailability. Concentrations of phenols are substantially higher in red beans than in white beans. The aim of this study was to compare iron bioavailabilities from red and white beans in a piglet hemoglobin repletion model. Fe deficient cross bred piglets (Hampshire*Landrace*Yorkshire) were used. Nutritionally balanced diets (except for Fe) were formulated to contain 50% precooked, dehydrated beans (either small red or Great Northern white). At age 5 wk, the piglets were assigned to 2 groups and fed diets containing either red or white beans for 4 wks. Weight and hemoglobin (Hb) concentrations were monitored weekly. Feed intakes were measured daily. Hemoglobin repletion efficiency (HRE) was calculated as the gain in total body hemoglobin Fe (Hb-Fe) divided by Fe intake. Hb concentrations, Hb-Fe gains and HRE were not different between the groups at any time point (p > 0.05). HRE values in the red bean group were 50% in the 1st week and 30% over the entire 4 week period. In the white bean group they were 56% and 26% respectively. Proline-rich protein mRNA concentrations in parotid glands were higher in the red bean group compared to the white bean group. These results show that iron bioavailabilities from red and white beans are similar and suggest that pigs adapt to the inhibitory effects of polyphenols on iron absorption by increasing the secretion of protective proline-rich proteins in the saliva.