CITREM is an emulsifier used in the food industry and contains citric acid esters of mono- and diglycerides (GCFE). It is generally recognized as safe but no publication on its digestibility under gastrointestinal conditions and impact on fat digestion was available. It was shown here that fatty acids are released from CITREM by gastric lipase, pancreatic lipase, pancreatic-lipase-related protein 2 and carboxyl ester hydrolase. A two-step in vitro digestion model mimicking lipolysis in the stomach and upper small intestine of term and preterm infants was then used to evaluate the digestibility of CITREM alone, CITREM-containing infant formula and fat emulsions, and isolated GCFE fractions. Overall, it was shown that fat digestion is not significantly changed by the presence of CITREM, and fatty acids contained in CITREM compounds are released to a large extent by lipases. Nevertheless, undigestible water-soluble compounds containing glycerol and citric acid units were identified, indicating that the ester bond between citric acid and glycerol is not fully hydrolyzed throughout the proposed digestion.

Short/medium chain fatty acids have well known health effects such as gut immune regulation and ketogenesis.

Widely consumed beverages such as red wine, tea, and cocoaderived products are a great source of flavanols. Epidemiologic and interventional studies suggest that cocoa flavanols such as (-)-epicatechin may reduce the risk of cardiovascular diseases. The interaction of (-)-epicatechin with food components including other polyphenols could modify its absorption, metabolism, and finally its bioactivity. In the present study we investigate (-)-epicatechin absorption and metabolism when coexposed with other polyphenols in the intestinal absorptive Caco-2 cell model. Depending on the type of polyphenols coadministered, the total amount of 39-O-methyl-epicatechin and 39-O-sulfate-epicatechin conjugates found both in apical and basal compartments ranged from 19 to 801 nM and from 6 to 432 nM, respectively. The coincubation of (-)-epicatechin with flavanols, chlorogenic acid, and umbelliferone resulted in similar amounts of 39-O-methyl-epicatechin effluxed into the apical compartment relative to control. Coincubation with isorhamnetin, kaempferol, diosmetin, nevadensin, chrysin, equol, genistein, and hesperitin promoted the transport of 39-Omethyl-epicatechin toward the basolateral side and decreased the apical efflux. Quercetin and luteolin considerably inhibited the appearance of this (-)-epicatechin conjugate both in the apical and basolateral compartments. In conclusion, we could demonstrate that the efflux of (-)-epicatechin conjugates to the apical or basal compartments of Caco-2 cells is modulated by certain classes of polyphenols and their amount. Ingesting (-)-epicatechin with specific polyphenols could be a strategy to increase the bioavailability of (-)-epicatechin and to modulate its metabolic profile.