Effect of Calcium, Tannic Acid, Phytic Acid and Pectin over Iron Uptake in an In Vitro Caco-2 Cell Model

Abstract

Calcium, phytic acid, polyphenols and fiber are major inhibitors of iron absorption and they could be found in excess in some diets, thereby altering or modifying the iron nutrition status. The purpose of this study is to evaluate the effect of calcium, tannic acid, phytic acid, and pectin over iron uptake, using an in vitro model of epithelial cells (Caco-2 cell line). Caco-2 cells were incubated with iron (10-30 μM) with or without CaCl2 (500 and 1,000 μM) for 24 h. Then, cells were challenged with phytic acid (50-150 μM); pectin (50-150 nM) or tannic acid (100-500 μM) for another 24 h. Finally, (55)Fe (10 μM) uptake was determined. Iron dialyzability was studied using an in vitro digestion method. Iron uptake in cells pre-incubated with 20 and 30 μM Fe was inhibited by CaCl2 (500 μM). Iron uptake decreased in cells cultured with tannic acid (300 μM) and CaCl2 (500-1,000 μM) (two-way ANOVA, p = 0.002). Phytic acid also decreased iron uptake mainly when cells were treated with CaCl2 (1,000 μM) (two-way ANOVA; p < 0.05). Pectin slightly decreased iron uptake (p = NS). Iron dialyzability decreased when iron was mixed with CaCl2 and phytic or tannic acid (T test p < 0.0001, for both) but not when mixed with pectin. Phytic acid combined with calcium is a strong iron uptake inhibitor. Pectin slightly decreased iron uptake with or without calcium. Tannic acid showed an unexpected behavior, inducing an increase on iron uptake, despite its low Fe dialyzability.

Anemia and Iron Deficiency Anemia in High School Girls in Nakhon Si Thammarat, Thailand

“…The information from the questionnaire indicates that most of the participants did not know about the inhibitory effect of tea and coffee on iron absorption (data not shown). 21,22 In addition, menstruation was not significantly correlated with IDA. This finding differs from a previous study in female Muslim students aged 13-15 years.…”

Estimation of the Iron Absorption from Ferrous Glycinate-loaded Solid Lipid Nanoparticles by Rat Everted Intestinal Sac Model

“…Phytic acid extensively exists in cereal-and/or legume-based dietary (Andrews et al, 2014). The absorption of iron can be severely restrained because of the formation of insoluble chelate compound by the coordination between the organic acid and iron.…”

“…It is well-known that the absorption of common iron salts could be severely blocked by external factors, such as phytic acid, divalent metal ions (Andrews et al, 2014;Olivares et al, 2012). Large quantities of phytic acid are contained in cereal-based and legumebased diets, which have been evidenced to exert a negative effect on iron absorption in humans.…”

Iron restriction increases myoglobin gene and protein expression in Soleus muscle of rats

“…This might suggest that when the supply of iron is reduced, responses are triggered leading to increased synthesis of this protein, which could represent a mechanism to facilitate the storage of iron in an attempt to keep their essential functions for O 2 transport through the tissues. The use of tannic acid as iron chelator is due its capacity to decrease iron bioavailability to the organism forming a tannin-iron complex (Disler et al 1975, Andrews et al 2014, Jamarillo et al 2015, Oh et al 2015. Just as occurred with the soleus muscle, which had an increase of Mb expression in the ironrestricted rat.…”