A Splash of Milk in Coffee May Have Health Benefits We Didn't Know About

It's no secret that coffee brings joy to people all over the world. It warms the soul, provides a focus boost, and brings people together, not to mention that it smells and tastes heavenly.

Science has shown that just the smell of coffee can make us feel alert, and luckily for coffee fans, there are health benefits, too. Coffee is a source of inflammation-fighting antioxidants and drinking it before exercise has fat-burning benefits.

Now a new study suggests that adding a dash of milk that contains protein can boost the health benefits of your cup of coffee.

Researchers from the University of Copenhagen in Denmark examined how antioxidants called polyphenols interacted with amino acids, the building blocks of proteins, and found that combining them has twice the effect on fighting cellular inflammation as polyphenols alone.

Polyphenols can be found in many foods, including coffee and tea, fruits and vegetables, red wine, and beer. Like other antioxidants, past studies suggest some polyphenols can prevent and slow the oxidation of healthy chemicals and protect our bodies from disease.

They are thought to do this in part by controlling inflammation, a complex immune response involving cells called macrophages that release several inflammatory mediators. Inflammation helps protect against infection, but if it isn't controlled properly, it can lead to diseases like type II diabetes, Alzheimer's, and Parkinson's.

Caffeic acid (CA) and chlorogenic acid (CGA) are polyphenols that are well known to have antioxidant and anti-inflammatory effects, but the authors wanted to find out if reactions that these polyphenols have with other chemicals can further affect immune regulation.

Adducts are products that are made when two or more molecules come together. In this case, the amino acid cysteine (Cys) – found in milk products – was combined with the polyphenols CA and CGA – found in coffee – to make the adducts CA–Cys and CGA–Cys.

To support this research, the authors successfully showed in another new study that polyphenols bind to proteins in a coffee drink with milk.

"Our result demonstrates that the reaction between polyphenols and proteins also happens in some of the coffee drinks with milk that we studied. In fact, the reaction happens so quickly that it has been difficult to avoid in any of the foods that we've studied so far," says food scientist and co-author on both studies, Marianne Nissen Lund.

In this study, the researchers used RNA-sequencing to study the immune-regulating effects of CA–Cys and CGA–Cys in macrophage cells subjected to artificial inflammation.

They also tested the effects of CA and CGA alone and compared them to a control group of macrophages not exposed to the polyphenols or the Cys adducts.

As they expected, the polyphenols CA and CGA inhibited inflammatory responses, in particular the production of reactive oxygen species (ROS), prostaglandin E2 (PGE2), and the cytokines interleukin-6 and tumor necrosis factor (TNF).

But when polyphenols CA and CGA were combined with amino acid cysteines found in milk proteins, their anti-inflammatory effects received a boost.

Macrophage cells exposed to polyphenols on their own, for instance, showed more than 2.5 times as much TNF activity as they did in the face of a polyphenols-cysteine adduct.

The only exception was ROS, which inexplicably increased in the macrophage when the polyphenol-amino acid combo was present compared to when the polyphenol was on its own.

"It is interesting to have now observed the anti-inflammatory effect in cell experiments. And obviously, this has only made us more interested in understanding these health effects in greater detail. So, the next step will be to study the effects in animals," says immunologist and senior author Andrew Williams.

Further research is needed to figure out why and what these results mean practically for human health. This study only examined how a single type of immune mediator reacts to coffee-like chemicals in a laboratory setting.

"Our results can be used as an important reference in applications of adducts formed from phenolic compounds and amino acids in future functional food or medicinal products that aim to modulate metabolic, neurological, or immune-related diseases," the researchers conclude in their paper.

We'll raise a cup of java to that!

The research has been published in the Journal of Agricultural and Food Chemistry.

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