LAUSANNE, Switzerland—Scientists at the Nestlé Research Center studied the metabolism and bioavailability of coffee antioxidants and found that they have a long-lasting release in the blood, even up to 12-14 hours after consumption.
The objective of the study was to quantify the amount of caffeic acid (CA) and ferulic acid (FA) equivalents in human blood plasma after coffee consumption. Healthy adults consumed the equivalent of two cups of soluble coffee (4g of coffee dissolved in 400 mL of water). Blood samples were collected for 12 hours and also at 24 hours after consumption, and then scientists quantified total CA and FA equivalents, as well as the major metabolites from the colon.
Scientists found that key colonic metabolites were detected in subjects 8-12 hours after drinking the coffee. This discovery indicates that the colon and gut microflora, in addition to the small intestine, have a major role in the metabolism and absorption of certain antioxidants in coffee.
The same research group also examined the effects of milk and non-dairy creamer on the bioavailability of these bioactives. For this study, healthy adult subjects were given either instant coffee, instant coffee plus 10% whole milk, or a pre-mix of instant coffee, sugar and non-dairy creamer. Blood samples were then collected 12 hours after coffee consumption. Polyphenolic equivalents in the blood plasma (caffeic, ferulic and isoferulic acids) were quantified and their bioavailability after consumption of the different coffee types was determined.
Results showed that the addition of whole milk to coffee did not affect the bioavailability of polyphenols, while the addition of non-dairy creamer delayed the appearance of polyphenol equivalents in the blood, but did not influence the total amount delivered. In conclusion, the availability of polyphenols after coffee consumption was the same for all three coffee types. “Coffee is a significant source of phenolic antioxidants in the diet,” said Mathieu Renouf, Nestlé Research scientist leading the study. “Our study confirms that polyphenols from coffee are as bioavailable in coffee with milk as they are in coffee without milk.”