Effects of dietary fat type and emulsification on carotenoid absorption: a randomized crossover trial

Although emerging evidence has suggested that the type and emulsification of dietary fat may be important to carotenoid absorption, these effects have not yet been validated in a human trial.

This study aimed to examine the effects of dietary fat type and emulsification on the bioaccessibility and bioavailability of carotenoids from a carotenoid-rich salad.

An identical salad was used for the in vitro and the human trial. This was paired with 28 g of one of the following 4 different fats: 1) nonemulsified olive oil, 2) emulsified olive oil, 3) nonemulsified coconut oil, and 4) emulsified coconut oil. The bioaccessibility of total carotenoids (TCs) was assessed by a simulated in vitro digestion model. Sixteen subjects consumed salad with 4 test fats in random order, and plasma triglyceride and carotenoid (lutein, zeaxanthin, α-carotene, β-carotene, and lycopene) concentrations were determined hourly for 10 h following the consumption. The absorption of TC and individual carotenoids was evaluated by the positive incremental AUC (iAUC) of plasma carotenoid concentrations.

The bioaccessibility of TC was greater with olive oil (24.0%) than with coconut oil (14.9%), and with the oil being emulsified (23.5%) rather than that being nonemulsified (15.4%). Similarly, the positive iAUC_1-10h of TC, α-carotene, and lycopene were 55.2%, 110.8%, and 45.8%, respectively, higher with olive oil than with coconut oil. Emulsified fat induced 40.0% greater positive iAUC_1-10h of TC than nonemulsified fat.

The type and emulsification of dietary fat are both essential to carotenoid absorption. Findings from this study may provide scientific support for designing excipient emulsions as potential dietary strategies to optimize the absorption of fat-soluble compounds. This study was registered at clinicaltrials.gov as NCT04323826.