Hands up if you can’t live without your morning coffee?
Ask people to name 3 foods they can’t live without and more often than not coffee will feature heavily.
Coffee contains hundreds of phytochemicals, of which the most well-known is caffeine, although it also contains phenols, vitamin B3, magnesium, and potassium. Early research into coffee focused on caffeine and its negative effects, which is why we were encouraged to reduce our consumption. Luckily, now that’s no longer the case!
Caffeine is still the most investigated component in coffee, and the caffeine content of a cup of coffee varies widely between brands and brew method. Caffeine has a half-life of 4-6 hours in the body – which is why it’s not recommended you have a cup in the evening – and is mainly metabolised in the liver. The other main components of interest in coffee are the antioxidants, which are metabolised in the intestines.
Coffee contains such a range of compounds, which is why it produces such a variety of physiological effects. These effects can also vary depending on what your tolerance to coffee is, that is, whether you’re a coffee novice or a long-term daily connoisseur. You can build up a tolerance to coffee in just a couple of days, and this tolerance effects the response your body has to coffee. Here are some of the main ones, both good and bad.
Physiological Effects of Coffee
Cardiovascular system: coffee has a short-term effect on reducing vasodilation, as well as increased arterial stiffness, which overall leads to a slight increase in blood pressure 1 hour after consumption. The caffeine in coffee also increases your heart rate, and makes you feel more awake. This is because the molecule adenosine, which usually makes you feel sleepy as it builds up throughout the day, has a similar molecular structure to caffeine, and so when caffeine binds to adenosine receptors instead, your body doesn’t get the same signal to say it’s tired! This is also why when the coffee wears off you can get a “crash”.
Lipid metabolism: coffee intake significantly increases total cholesterol, LDL cholesterol (the “bad” kind), and triglycerides. Not so good. However, it does also produce a favourable change in the LDL:HDL cholesterol ratio, and the antioxidant in coffee may help to protect from oxidation of LDL cholesterol, but this is still uncertain.
Carbohydrate metabolism: caffeine increases insulin resistance by 15-30%, however long-term coffee consumption is favourable overall, as in the long-term increased consumption is linked to decreased fasting glucose and insulin levels, which is good as it means greater insulin sensitivity.
Exercise: there is consistent evidence supporting the performance-enhancing effects of both coffee and caffeine for endurance-based exercise. (Side note to students: writing an essay sadly doesn’t fall under this category)
Impact of Coffee on Disease
The potential effects of coffee on various non-communicable diseases have been studied, and while links have been drawn in some cases, often we’re still unsure of the exact mechanisms by which is works. Overall though, drinking coffee is associated with a reduced risk of all-cause mortality, not by much, but a little bit, and there’s minimal additional effects beyond 3 cups per day.
Coffee consumption is associated with possible decreased risk of cardiovascular disease, or at the very least doesn’t increase risk, and is associated with a slight decreased risk of stroke. Increased consumption of coffee is linked to decreased incidence of diabetes, with each daily cup of coffee producing a 7% reduction in risk. There is also a reduced risk of liver disease, although the mechanism is still unclear.
Coffee may even have a protective effect on Alzheimer’s disease, although this is not certain, and reduces the risk of Parkinson’s disease by 33%. Positives all round!
There is some evidence to suggest that coffee may be linked to increased risk of osteoporosis, but this has mainly been found in at-risk populations (such as the elderly), and is still inconclusive. Much of the data on coffee and cancer is also inconclusive, although overall it leans towards a protective effect. This doesn’t mean coffee cures cancer guys!!!
Of course what this doesn’t include is the social aspect of coffee – how often have you heard the phrase “let’s go for coffee” or “let’s catch up over coffee” recently? Meeting over coffee is such a key part of our culture now, and the social aspect of it is so important. Populations who live the longest tend to have a few things in common: they eat lots of plants, they stay active, and they stay social. It’s the same reason why in some studies people who drink a little alcohol live longer than people who drink no alcohol – the social aspect! Meeting in a cute café for a cup of coffee and a catch-up with an old friend makes us happy, which is just as important as being healthy!
Ultimately, having a morning coffee, far from doing you any harm, is actually more likely to do you good! A single cup won’t even produce diuretic effects, that only occurs after more than 500 to 600 mg of caffeine a day, so drink up!
The Metabolic and Performance Effects of Caffeine Compared to Coffee during Endurance Exercise
The impact of coffee on health