A randomized crossover trial of the effects of fermented milk on carotenoid absorption in healthy participants

Background In humans, the bioavailability of β-carotene from vegetables is approximately 5˗10%. To maximize the health benefits of dietary carotenoids it is important to enhance their bioavailability. We reported previously that co-ingestion of fermented milk (100 g) plus vegetables enhanced the bioavailability of carotenoids. Objective The objective of this study was to compare the differences in plasma levels of various carotenoids after co-ingesting them with fermented milk. Methods We conducted a randomized crossover study of 10 healthy males in two groups across two periods. A beverage containing carotenoids with and without fermented milk (50 g) was consumed. Blood samples were collected before ingestion and 2, 4, 6, and 8 h after ingestion and plasma β-carotene, lycopene, lutein, astaxanthin in the triacylglycerol-rich lipoprotein (TRL) fraction and crocetin in all fractions were measured. Results The incremental area under the curve of the TRL fraction of plasma β-carotene, lycopene, lutein, astaxanthin, and all fractions of plasma crocetin were significantly higher after the ingestion of carotenoids with fermented milk versus carotenoids alone. Conclusions These results suggest that the absorption of various carotenoids may be improved when consumed with fermented milk. Furthermore, it was also found that carotenoid absorption was enhanced at lower doses than previously reported for fermented milk. Clinical trial registry number and website: UMIN clinical registry system (trial ID: UMIN000052407), https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000059825