Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans

Abstract

The objective of the study is to determine the effect of copper (Cu) plus the reducing agent ascorbic acid (AA) on the absorption of non-heme iron (Fe). Experimental study with block design in which each subject was his own control. After signing an informed consent, 14 adult women using an effective method of contraception and negative pregnancy test received 0.5 mg Fe, as ferrous sulfate, alone or with Cu, as copper sulfate, plus ascorbic acid (AA/Cu 2/1 molar ratio) at 4/1; 6/1 and 8/1 Cu/Fe molar ratios as an aqueous solution on days 1, 2, 14, and 15 of the study. Fe absorption was assessed by erythrocyte incorporation of iron radioisotopes (55)Fe and (59)Fe. Geometric mean (range ± SD) absorption of Fe at 4/1 and 6/1 Cu/Fe molar ratios (and AA/Cu 2/1 molar ratio) and Fe alone was 57.4 % (35.7-92.1 %), 64.2 % (45.8-89.9 %), and 38.8 % (20.4-73.8 %), respectively (ANOVA for repeated measures p < 0.001; post hoc test Scheffé, p < 0.05). This is attributable to the enhancing effect of AA on non-heme Fe absorption; however, Fe absorption at Cu/Fe 8/1 molar ratio was 47.3 % (27.7-80.8) (p = NS compared with Fe alone). It was expected that Fe absorption would have been equal or greater than at 4/1 and 6/1 molar ratios. Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.

The Association between Maternal Dietary Iron Intake during the First Trimester of Pregnancy with Pregnancy Outcomes and Pregnancy-Related Complications

“…Although both iron groups are found in foods, the animal-based foods (including meat, seafood, and poultry) are the primary source of the heme iron, whereas the plant-based foods (including legumes, fruits, and vegetables) are considered the primary source of non-heme iron [2]. Heme iron has higher bioavailability than non-heme iron [3], because non-heme iron absorption can be influenced by other dietary components such as phytates, tannins, ascorbic acid, and copper [4,5].…”

Exploring the interactions between metabolic dysfunction-associated fatty liver disease and micronutrients: from molecular mechanisms to clinical applications

“…Zinc and selenium have been linked to reduced cardiovascular risk ( 109 ), and Vitamin D and zinc both enhance immune function ( 154 ). Additionally, copper and ascorbic acid can interfere with non-heme iron absorption ( 155 ). These findings indicate a delicate balance among trace elements, crucial for maintaining overall body homeostasis.…”

Iron Metabolism in Normal and Pathological Pregnancies and Fetal Consequences

“…Enterocytes absorb 15% of heme iron and 85% of non-heme iron, non-heme iron mainly coming from plantbased food [19,20]. Iron absorption can be modified by dietary components, such as ascorbic acid and polyphenols [21,22]. At the apical side of enterocytes, Fe 3+ is reduced to Fe 2+ by duodenal cytochrome B (DCYTB) [23][24][25] and carried into the cells by divalent metal transporter 1 (DMT1 = SLC11A2) [26].…”