The effect of proteins from animal source foods on heme iron bioavailability in humans

• Heme iron from RBC concentrates is better absorbed than heme iron from hemoglobin.
• Heme iron absorption is decreased when ingested with fish and chicken meat.
• Collagen, casein and albumin did not affect the heme iron absorption.

Forty-five women (35–45 year) were randomly assigned to three iron (Fe) absorption sub-studies, which measured the effects of dietary animal proteins on the absorption of heme Fe. Study 1 was focused on heme, red blood cell concentrate (RBCC), hemoglobin (Hb), RBCC + beef meat; study 2 on heme, heme + fish, chicken, and beef; and study 3 on heme and heme + purified animal protein (casein, collagen, albumin). Study 1: the bioavailability of heme Fe from Hb was similar to heme only (∼13.0%). RBCC (25.0%) and RBCC + beef (21.3%) were found to be increased 2- and 1.6-fold, respectively, when compared with heme alone (p < 0.05). Study 2: the bioavailability from heme alone (10.3%) was reduced (p < 0.05) when it was blended with fish (7.1%) and chicken (4.9%), however it was unaffected by beef. Study 3: casein, collagen, and albumin did not affect the bioavailability of Fe. Proteins from animal source foods and their digestion products did not enhance heme Fe absorption.