Carotenoid interactions during absorption anti in postabsorptive metabolism have been observed in both human and animal studies. We reviewed the mutual interactions reported between lutein and β-carotene and report new data on the postprandial β-carotene and retinyl ester response in the triglyceride-rich plasma lipoprotein (TRL) fraction in volunteers after a single test meal with β-carotene alone, or β-carotene combined with lutein or lycopene. Results indicate an inhibitory effect of lutein on β-carotene absorption, but apparently not on β-carotene cleavage. In a comparative study with two β-carotene/lutein ratios (2:1 and 1:2, respectively), this inhibitory effect of lutein was found to be most marked when lutein was the predominant carotenoid. In studies on plasma (serum) response also an inhibitory effect of β-carotene on lutein response was observed.