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Polyphenolic antioxidants are mainly absorbed through passive paracellular permeation
regulated by tight junctions. Some fatty acids are known to modulate tight junctions. Fatty
acids resulting from the digestion of edible oils may improve the absorption of polyphenolic
antioxidants. Therefore, we explored the effect of three edible oils on the intestinal absorption of caffeic acid. Rats were fed with soybean oil and caffeic acid dissolved in distilled
water. Caffeic acid contents in the plasma collected up to 1 hr were quantified. The experiment was repeated with coconut oil and olive oil. Component fatty acids of the oils were individually tested in vitro for their effect on permeability of caffeic acid using Caco-2 cell
monolayers. Highest absorption of caffeic acid was observed in animals fed with coconut oil.
In vitro transport percentages of caffeic acid in 2.5 mmol/L solutions of fatty acids were
22.01±0.12 (lauric), 15.30 ± 0.25 (myristic acid), 13.59 ± 0.35 (linoleic acid), 3.70 ± 0.09
(oleic acid) and 0.10–2.0 (all other fatty acids). Lauric acid and myristic acid are the two
major fatty acids present in coconut oil. Therefore, these fatty acids may contribute to the
higher absorption of caffeic acid in the presence of coconut oil.
