The chemistry of coffee (polyphenols) and milk (amino acids)

Perhaps you came across this research in the news: adding milk to coffee would increase the anti-inflammatory effects of the later. The study is called Phenolic Acid–Amino Acid Adducts Exert Distinct Immunomodulatory Effects in Macrophages Compared to Parent Phenolic Acids – yes it is a bit cryptic!

The study looks at how the amino acids contained in milk combine with the polyphenols (anti-oxidants) naturally occurring in coffee. The scientists found that « as a polyphenol reacts with an amino acid, its inhibitory effect on inflammation in immune cells is enhanced », and this happens in milky coffee drinks. This association likely has the beneficial effect of fighting inflammation.

These results were observed in-vitro, and the University of Copenhagen who led the research, is already planning to investigate in animals and humans.

What this study also suggests, is that this reaction between polyphenols and amino acids occurs in other foods where proteins and fruits or vegetables are combined, for example in a smoothie.