Drinking instant coffee with or without milk produced the same uptake levels of coffee’s antioxidants, including caffeic acid, ferulic acid, and isoferulic acid, according to findings of a study with nine people published in The Journal of Nutrition.
“Up until now there has been very little known about how proteins, especially from milk, influence the bioavailability and efficacy of coffee antioxidants,” said lead author Mathieu Renouf from Nestlé Research Center in Lausanne. “Our study is the first to show that coffee antioxidants are just as bioavailable in coffee with milk, as they are in black coffee.”
On the other hand, the uptake of caffeic and ferulic acids was lower when coffee was made with non-dairy creamer and sugar, said the NRC scientists.
“Only differences in [the maximum blood concentration and the time needed to reach that maximum] for the sugar/ non-dairy creamer group were observed compared with the Coffee treatment, suggesting a modulation of plasma bioavailability, although the overall [blood levels achieved] remains the same compared with a classic black cup of coffee,” stated the researchers.
Benefits of the bean
The beverage, and its constituent ingredients, has come under increasing study with research linking it to reduced risk of diabetes, and improved liver health.
Coffee, one of the world's largest traded commodities produced in more than 60 countries and generating more than $70bn in retail sales a year, continues to spawn research and interest, and has been linked to reduced risks of certain diseases, especially of the liver and diabetes.
Unanswered questions answered
Previous studies have suggested that milk may influence the absorption of polyphenols, particularly green tea polyphenols, but the results in this area have been conflicting. “There are no data on the bioavailability of [coffee’s antioxidant] compounds when other foods are consumed with, or added to, black coffee,” explained the researchers.
Renouf and his co-workers recruited nine healthy participants with an average age of 33.7 and randomly assigned them to drink instant coffee, instant coffee and plus whole milk (10 per cent), or instant coffee plus sugar and nondairy creamer in a cross-over design. All three drinks provide a 332 milligram dose of antioxidant chlorogenic acids.
Results showed that blood levels, and times to achieve these levels, was no different between the instant coffee and the milky instant coffee with regards to caffeic acid, ferulic acid, and isoferulic acid equivalents, said the researchers.
“As a conclusion, adding whole milk did not alter the overall bioavailability of coffee phenolic acids, whereas sugar and nondairy creamer affected the [the maximum blood concentration and the time needed to reach that maximum] but not the appearance of coffee phenolics in plasma,” concluded the researchers.
The subject of bioavailability will be discussed in more detail at the upcoming conference, NutraIngredients Antioxidants 2010: Science, Testing and Regulation. For more information about the conference, please click here.
Source: Journal of Nutrition
2010, Volume 140, Pages 259-263
"Nondairy Creamer, but Not Milk, Delays the Appearance of Coffee Phenolic Acid Equivalents in Human Plasma"
Authors: M. Renouf, C. Marmet, P. Guy, A.-L. Fraering, K. Longet, J. Moulin, M. Enslen, D. Barron, C. Cavin, F. Dionisi, S. Rezzi, S. Kochhar, H. Steiling, G. Williamson