The Effect of an Iron Supplement on Lycopene Metabolism and Absorption During Digestion in Healthy Humans

Scope: To investigate the formation and absorption of lycopene (LYC) metabolites in the human upper gastrointestinal lumen, in the absence and presence of iron.

Methods: Healthy males (n = 7) consumed test meals that deliver ≈22 mg LYC + ≈0.3 mg apo-lycopenals from oleoresin without (-FeSO₄ ) and with ferrous sulfate (160 mg, +FeSO₄ ). Subjects were intubated with a naso-gastric/naso-duodenal tube. Digesta, blood plasma, and the triglyceride-rich lipoprotein (TRL) fractions of plasma were analyzed using LC-MS/MS, to measure LYC and apo-lycopenoids.

Results: Digesta LYC concentrations increased with time (p = 1.2 × 10^-7 ), decrease with time × iron (p = 1.1 × 10^-5 ), and remain ≈200× higher than apo-lycopenals/lycopenone. Digesta apo-8'-, -10'-, -12'-, -14'-, -15-lycopenal, and apo-13-lycopenone concentrations increased with time (p < 0.01), apo-12'-, -14'-, -15-lycopenal, apo-13-lycopenone increase with iron (p < 0.05), and time × iron decrease apo-8'-, -10'-, -12'-, -14'-, -15-lycopenal, apo-13-lycopenone concentrations (p < 0.01). A 1.9-fold decrease in LYC TRL area-under-the-time-concentration-curve is observed after the test meal +FeSO₄ versus the test meal -FeSO₄ (p = 0.02). Apo-lycopenals were detected in later TRL fractions, and no apo-lycopenols or apo-lycopenoic acids were observed in any samples.

Conclusions: FeSO₄ reduces LYC absorption. Apo-lycopenals appear to be absorbed from foods, and not made in significant quantities during digestion.