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.


Coffee: friend or enemy?

There is more to coffee than just a drink: having a coffee is a social activity. You share it with your family, friends or colleagues, it can even be a way to start a conversation with a random fellow drinker. Coffee can also be a solitary pleasure, as a matter of fact, I am enjoying a little black drink while writing this post, and it feels both energising and comforting.

Widely consumed across the globe, coffee has been examined in all its aspects by thousands of researchers. This is a fascinating topic, with publications spanning from the biochemistry of coffee compounds to its socio-cultural influence and potential incorporation in public health policies.  This is also a controversial topic: some people believe it is dangerously addictive, some that it is a magic cure. Let’s have a closer look at the latest evidence about its possible health benefits and harms.

A coffee with my best self at the legendary Café Tortoni in Buenos Aires.

Health benefits of coffee consumption

Amazingly, a very recent meta-analysis showed that coffee, included decaf, is consistently associated with lower mortality! Mortality from cardiovascular disease (CVD), coronary heart disease (CHD), and stroke was lower in coffee drinkers, with the greatest association at 3 cups a day.

Cohort studies show a lower incidence of cancer in coffee drinkers vs non-drinkers. A beneficial effect is indicated by a linear dose-response in prostate, endometrial, melanoma, and liver cancers. Generally, coffee is associated with lower risk of liver diseases such as non-alcoholic fatty liver disease, liver fibrosis and cirrhosis, gallstones.

At all levels of consumption, coffee and decaf coffee are both consistently with lower risk of type 2 diabetes, Parkinson’s disease, depression and cognitive disorders including Alzheimer’s.

Detrimental effects of coffee

Paradoxically to its beneficial effects on CVD, CHD and stroke, the little black drink is associated with an unfavourable lipid profile, with lower HDL and higher LDL cholesterol and triglycerides.
In smokers, coffee intake is associated with higher incidence of lung cancer.

High coffee consumption is associated with lower birthweight and pregnancy loss, so pregnant women may want to decrease their intake.

Coffee and me… as a person and a nutritionist

I am not a born coffee lover and started to drink it only in my late thirties: I was back to study full time, my brain was not as efficient as when I was young, and coffee proved helpful in stimulating my neurons. Before that, I « socialised » at the coffee machine with water or tea, only ingesting coffee in the form of a tiramisu!

However – nutritionist cap on – the amount of scientific evidence of its health benefits convinced me that, as a little black dress, the little black drink was doing me good. Yes, I have it black: no milk, no sugar. Obviously a « I-don’t-know-what’s-in-it » super sugary 2-pint coffee served by a mermaid (is it still coffee?) will not do you as good, but that’s another story…

So, if you are a heavy coffee drinker, pregnant, or have a health condition, you may want to reduce your consumption (the golden rule always prevails: everything in moderation!), otherwise, enjoy your cuppa, and the blackest, the best!