Exopolysaccharides from milk fermented by lactic acid bacteria enhance dietary carotenoid bioavailability in humans in a randomized crossover trial and in rats

Abstract

Background Dietary supplementation with carotenoids can have beneficial health effects, but carotenoids are poorly absorbed. Objectives We aimed to evaluate how milk fermented by lactic acid bacteria affects dietary carotenoid bioavailability in humans and rats and to investigate mechanisms by which active components in milk fermented by Lactobacilli enhance dietary carotenoid absorption. Methods Male rats (n = 8/group) were administered β-carotene or β-carotene + fermented milk. Rats (n = 6/group) were also pretreated with ezetimibe, a cholesterol absorption inhibitor, to investigate β-carotene transport mechanisms. In humans, 3 studies were conducted using a randomized crossover method. Subjects (n = 16/study) consumed a vegetable (carrot, tomato, or spinach) drink alone or with a fermented milk drink. Blood samples were collected at various time points after consumption. Results In rats, the serum β-carotene area under the concentration–time curve (AUC) was significantly higher for the β-carotene + fermented milk than for β-carotene only. A significant correlation (r = 0.83, P < 0.001) between the exopolysaccharide (EPS) content of fermented milk and serum β-carotene AUC was observed. Ezetimibe treatment did not suppress elevations in serum β-carotene concentrations induced by fermented milk ingestion. In humans, the incremental area under the concentration–time curve (iAUC) for β-carotene in the plasma triacylglycerol-rich lipoprotein (TRL) fraction was significantly (1.8-fold, range: 0.6–3.9) higher when carrot + fermented milk was consumed compared with carrot drink alone. A significantly (6.5-fold, range: 0.04–7.7) higher iAUC for lycopene in the plasma TRL fraction was observed for subjects who consumed tomato + fermented milk compared with tomato drink alone. A significant increase in plasma lutein in all fractions was observed after consumption of spinach + fermented milk, but not with spinach drink alone. Conclusions Co-ingestion of β-carotene and fermented milk significantly increased dietary β-carotene bioavailability in humans and rats. EPSs could affect the physical properties of fermented milk to enhance dietary β-carotene absorption mediated by simple diffusion mechanisms. These findings may be relevant for methods to increase dietary carotenoid bioavailability. This trial was registered at umin.ac.jp/ctr as UMIN000034838, UMIN000034839, and UMIN000034840.

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“…However, the use of carotenoids is complicated by the lack of their solubility in water due to their glycosylated form [ 211 ]. Therefore, poor absorption and bioavailability is a disadvantage associated with the introduction of carotenoid-rich food into the diet [ 213 ].…”

“…Regarding the content of carotenoids in food sources, 100% watermelon juice was demonstrated to effectively increase serum lycopene in older women belonging to the group of people that are at risk for low carotenoid intake [ 214 ]. However, the disadvantage of the carotenoids is their poor absorption and bioavailability [ 213 ]. An illustrative example of the bioavailability of carotenoids can be demonstrated by an example of phytoene, phytofluene, lycopene, and β-carotene that represent the main tomato carotenes.…”

“…Furthermore, exopolysaccharides from milk fermented by lactic acid bacteria enhanced dietary carotenoid bioavailability in humans and rats. The dietary β-carotene absorption could be enhanced via simple diffusion mechanisms mediated by exopolysaccharides affecting the physical properties of fermented milk [ 213 ]. The improved bioavailability of carotenoids, due to the other food constituents or co-consumption is shown Table 4 .…”

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