I’m not a big coffee drinker myself but I do enjoy a latte every now and again. Coffee has been known to be a vice – after all, it’s a stimulant, it’s addictive and is even sometimes referred to as a “legal drug”. I wanted to explore this in a bit more detail to understand how harmful coffee actually is and what makes it so.
How does coffee work? Caffeine is similar to the molecule called adenosine in your brain. When adenosine binds to enough receptors, it signals the brain that it’s time to sleep. Caffeine gets there first and binds to the receptors preventing adenosine from binding so the brain doesn’t get the signal to sleep. On top of that, elevated levels of adenosine in the blood cause the release of adrenaline, which is a stimulating hormone. After caffeine is metabolised, the extra adenosine floods the brain signalling it to sleep, that’s why some people experience a “crash” of tiredness and fatigue a few hours after drinking coffee.
To my surprise, looking at the scientific literature regarding coffee and caffeine uncovered some unexpected findings. First of all, the harmful effects that coffee has been accused of, such as increased risk of cardiovascular disease, arrhythmia and heart insufficiency, haven’t been shown to be affected by coffee intake in any way. On the contrary, many studies point to a positive association between drinking coffee and reduced risk of some major diseases, such as diabetes and liver disease. Long term caffeine intake seems to have protective qualities against stroke, Alzheimer’s and Parkinson’s diseases. In particular, the results from a 21 year follow-up study indicated that drinking 3-5 cups of coffee per day was associated with a 65% (yes, you read it right) decreased risk of dementia and Alzheimer’s disease in later life.
A large study of over 500,000 people from 10 countries showed that people with a higher intake of coffee (over 3 cups a day) have lower mortality (12% lower for men and 7% lower for women) compared to non-drinkers.
Coffee is also known to increase blood pressure but a study has demonstrated that caffeine tolerance diminishes this effect, which means that regular coffee drinking does not increase the risk of hypertension.
What are the downsides of drinking coffee? To be honest, there aren’t many.
- Some people are more sensitive to caffeine than others and these people may experience sleep disturbance and feeling of anxiety after caffeine intake. If you have sleep issues or suffer from anxiety maybe coffee is not your drink of choice.
- Coffee is, indeed, addictive, which means it can cause some withdrawal symptoms if you cut it off. Usually it’s headaches, fatigue and irritability but the symptoms will pass completely in about 10 days. Withdrawal can start as soon as 12 to 24 hours after last use, that’s why that first cup in the morning is so important for heavy coffee drinkers.
- Coffee contains natural constituents called diterpenes, which have been associated with higher total and “bad” cholesterol concentrations. However, filtering coffee removes most of the diterpenes from the drink.
- Another thing to keep in mind is that some coffee drinks contain high amounts of sugar and calories. For example, Grande Caramel Macchiato with coconut milk in a popular coffee shop contains over a 1000 calories and 31g of sugar – about 3 times more than the same size skimmed milk cappuccino. Be mindful of this when you order your favourite drink.
So should you suddenly turn into a heavy coffee drinker? Not so fast. The problem with the majority of the studies mentioned above is that they are observational. That means that the researched asked the participants how much coffee they drink and then followed them to see any incidents of diseases. We cannot be sure if any outcomes have actually been caused by coffee intake per se. Maybe people who drink a lot of coffee generally have more income (since they can afford to have 5 coffees per day) and that’s what contributed to their decreased illness / mortality risk. Or maybe these people tend to be more social and that influences their wellbeing, or maybe it’s something else entirely. We can speculate but we don’t know for sure if coffee is necessarily causing all these health benefits and we also don’t know how it happens or what mechanisms are at play.
On the other hand, results do seem to be pretty consistent across different studies and Food Regulation Authorities have concluded that caffeine consumption is not harmful if consumed at levels of 200mg in one sitting or 400mg daily. Caffeine levels vary greatly but, as an example, a medium latte at a chain coffee shop contains about 150-175mg of caffeine. So feel free to enjoy that cup of coffee and possibly improve your health at the same time!
Coffee consumption is linked to many health benefits but it’s not been proven as the cause. Unless you are sensitive to caffeine or suffer from anxiety or sleep problems, it’s safe and possibly even beneficial to have a couple of coffees per day.