Walking down the street back home in Sofia the other day (long live vacations!), I overheard two ladies talking to each other, passionately:
Girl1: I don’t know how to help him anymore…
Girl2: I don’t mean to be condescending, but I kept telling him – as long as he keeps putting milk in his coffee, it immediately stops working and will not help his low blood pressure!
Her totally condescending tone aside, I got to thinking. Does coffee do anything for blood pressure in the first place? And does adding anything to your coffee makes a difference on how powerful it is?
Here is the last drop in the coffee and the truth on milking it.
The roasted “super-hero”
Beneficial effects attributed to coffee are most often associated with caffeine and phenols. These compounds have complex chemical structures. They are often are believed to have antioxidant activity.
In any case, there are many studies which point to the beneficial effects of coffee. It can allegedly help prevent conditions like some cancers, cardio-vascular diseases, gallbladder stones. Lately, some research even showed that neuro-degenerative conditions and dementia are positively influenced by coffee. However, in most of these studies, the measured effect is small. It by no means points to coffee as a panacea for such serious conditions or as an alternative to pharmacological treatments.
On the contrary, some studies show that coffee is certainly best avoided by people with high cholesterol or existing cardiac conditions. Additionally, caffeine might counteract the action of contraceptive pills and post-menopausal hormones.
A more detailed scientific review of the risks and benefits of coffee were published in this article of Messina and colleagues (here: in the Journal Biology and Medicine).
But what about the milk?
Whether or not you subscribe to the believe that coffee makes your life better, there is still the original question to answer. Does adding milk to your cup change the way coffee is absorbed by your body and thus – its effect on you?
An article, published in the Journal Physiology and Behavior, studied scientifically exactly this aspect of preparing your power-cup.
So far, few studies exist, which experimentally study the potential for coffee additives to change the absorption of beneficial coffee-compounds.
Most of them show that compounds in milk can indeed bind some of the aromatic chemicals in coffee, as well as caffeine itself.
Many health benefits are correlated to coffee in multiple human trials. While possible, those effect should always be taken with a grain of salt. Human trials are incredibly hard to control for bias and confounding factors of the lifestyle of the tested people.
However, it seems that in the experiments done for those studies, milk-coffee binding is reversible by the enzymes in the gut. This means that you can enjoy a cup of refreshing beverage with milk, if that’s your preference, and not worry that you are not taking the full benefit of that cup!
A more worthy concern
It is probably worth being more concerned if the things you add to your coffee are good for you in general. Full-fat milk, cream, and sugar might not be the best choice, especially if you drink a lot of coffee each day. Those are plenty of extra calories which you can do without. Also, in the long run, the negative effects of excessive fats and sugar can negate the positive effects of coffee. They are known to contribute to diabetes, cardiac conditions and obesity.
Back to eavesdropping
So back to our two ladies on the street. Yes, they were both wrong. Caffeine does affect blood pressure, but its effect is rather short-lived. Some studies show that it peaks at about 40 minutes and subsides within 6 hours. So, the first flaw in their assumption is that coffee can have a long-term effect on the low blood pressure of the person X and permanently solve his health problem. The second mistake was, the assumption that adding milk to the coffee diminishes its effect. At best, this not at all the case. Most probably, the relationship between coffee and milk is just not as simple as that.