Objective Lutein is an antioxidant carotenoid that concentrates in the macular region of the retina. Human milk contains lutein that is higher, on average, than the innate lutein in infant formulas. We examined serum lutein in infants fed human milk or formulas unfortified and fortified with lutein.

Methods This prospective, double-blinded study enrolled healthy infants aged 9–21 days. Infants were exclusively formula-fed (FF) or human milk-fed (HM) for 12 weeks. FF infants were randomized to formulas containing 22 (control), 45, 119 or 224 mcg/L lutein. Blood was drawn at enrollment and week 12. Human milk samples were collected from mothers of HM infants at weeks 4, 8 and 12.

Results Thirty-four infants completed the study (13 HM, 21 FF). Mean human milk lutein concentration was 24.3 mcg/L (95% CI 16.7 to 32.0) and stable over time. The HM group had 6-fold higher serum lutein (mean 69.3 mcg/L; 95% CI 40.3 to 119) than control (11.3 mcg/L; 8.1 to 15.8) at week 12. Infant serum lutein increased from baseline in each FF group except control. Linear regression revealed for every 1 mcg/L lutein in diet, HM infants had a greater increase in serum lutein (slope 3.7; p<0.001) than FF infants (slope 0.9; p<0.001). Mean serum lutein in the 119 mcg/L group (mean 107.5 mcg/L; 95% CI 87.4 to 132) was closest to the HM group.

Conclusion Formula fortification with lutein resulted in a dose-dependent increase in serum lutein. These data provide support for lutein fortification of formula in order to approximate serum concentrations observed in human milk-fed infants.