For some people, coffee is deserving of its own essential food group. But could be more than just a way to achieve functioning human capacity first thing in the morning? You may have seen media headlines in the past warning about health risks of coffee. But now that the science has matured, coffee turns out to be one of the most surprisingly positive health stories of recent years. Forget about the latest superfood trend, coffee is where it is at.
Coffee, brew, black gold or go juice. Whatever you call it, coffee is the world’s second-most popular beverage after tea. Around the planet, it has been estimated that over 2.2 billion cups of coffee are drunk every day.
So just what is in your daily brew? Coffee contains several useful nutrients including riboflavin, niacin, magnesium, potassium, and various antioxidants as well as a bunch of other natural plant chemicals. In fact, one estimate has found that the typical United States diet provides more antioxidants from coffee than it does from fruits and vegetables combined. And then, of course, there’s the caffeine.
Caffeine and your brain
Caffeine is the most consumed psychoactive substance in the world – and I’m talking about both legal and illegal substances here. Soft drinks, tea and chocolate all contain caffeine, but coffee is the biggest source.
Caffeine is a stimulant. In your brain, it blocks the function of an inhibitory neurotransmitter called adenosine. By blocking adenosine, caffeine increases activity in the brain and releases other neurotransmitters like norepinephrine and dopamine. This reduces tiredness and makes you feel more alert. That all means that caffeine can lead to a short-term boost in brain function, improving mood, reaction time, vigilance, and general cognitive function. But any regular coffee drinker knows this already.
Coffee and your health
Maligned for many health ills — from stunting your growth to causing heart disease – coffee is a good example of how conflicting nutrition research gives mixed messages to the public. One day coffee is reported as being good for us, and the next day it is harmful. All the while, people continue to switch off to such conflicting reports and keep on enjoying their favourite coffee beverage of choice as part of their morning routine.
Fortunately, now that the coffee research has really matured, we are in a good position to see how the health ledger stacks up for coffee. The potential health benefits of coffee have been outlined in a major scientific review published in 2016.
The review looked at over 1,200 individual studies where coffee was studied in regards to any positive or negative health effects. The big ones included cancer, heart disease, type 2 diabetes, liver disease, neurological disorders, and longevity and each was picked apart to see what the research said.
And after all that analysing and synthesising, what was the conclusion? The health benefits of moderate coffee consumption clearly outweighed the risk for most of the health outcomes looked at. A definition of moderate here was considered 3 to 4 cups a day – that’s a definition of moderate that agrees with me a lot.
For type 2 diabetes it is good news with regular coffee drinkers having up to a two-thirds reduced risk of developing this condition. One review of 18 studies involving almost half-a-million people found that for each daily cup of coffee a person had, it was linked with a 7 percent lower risk of developing type 2 diabetes. And that was after making allowances for other lifestyle habits that regular coffee drinkers had that non-drinkers did not.
Coffee is also linked to a reduced risk of some cancers. Coffee decreases the risk of liver and endometrial cancer with the level of evidence set at ‘probable’ by the World Cancer Research Fund. There is also some suggestive evidence that coffee can lower the risk of cancer of the mouth, pharynx, and larynx as well as even skin cancer. And no concerns have been raised about coffee elevating the risk of any form of cancer.
Coffee is also showing promise in reducing the risk of, and even treating, some neurologic diseases. To start with, coffee drinkers are known to have up to a 60 percent lower risk of developing Parkinson’s disease. And people who drink coffee may also be less likely to experience depression and conditions such as Alzheimer’s disease. So, there seems a common link here with coffee having a favourable benefit on the neurologic system.
As an aside, extending the work done finding that coffee is linked to reducing the risk of Parkinson’s disease, one small clinical trial has found that people with Parkinson’s disease given a daily dose of caffeine gained improvements in their movement symptoms.
People with Parkinson’s disease given a 100-milligram caffeine tablet (equivalent to a strong cup of coffee) twice a day for 3 weeks and then increased to 200 milligrams twice a day for the following 3 weeks showed a substantial improvement in motor symptoms, with a noticeable improvement in speed of movement and less muscle stiffness. The results look promising and if confirmed in larger clinical studies, then caffeine could become a safe treatment option for some of the symptoms seen in Parkinson’s disease.
A longer life
Coffee is also linked to longevity with regular drinkers living longer although it is hard to put an exact number of years on it. Looking at causes of death, it seems coffee drinkers are less likely to die from infections, injuries, accidents, respiratory diseases, diabetes, stroke and heart disease. Decaf coffee appears to have favourable benefits too so it is likely not all to do with the caffeine, but rather a combination of all the antioxidants and other natural chemicals found in coffee working together that is giving the benefit.
Caffeine powers sports performance
Moving out of the world of health and into that of sport and human performance, coffee has a special place thanks to its caffeine content. Caffeine is one of the few sports supplements that have quality scientific evidence behind it to support a real-world sports-performance benefit.
There is good evidence that caffeine use improves endurance capacity such as exercise time to fatigue and endurance-based time-trial activities of varying duration. And this endurance benefit is seen across cycling, running, rowing and many other sports. One estimate equates its benefit to increasing time to exhaustion by about 3 percent. In the world of elite sport, this is a huge benefit.
In fact, caffeine was one of the few supplements to get the tick for having good evidence behind it in the 2018 IOC Consensus Statement on dietary supplements for use by high-performance athletes.
So, how does caffeine work its magic? Caffeine is a stimulant that elicits many physiological and psychological effects in the body. While its mechanism of benefit is not fully understood, caffeine may improve vigilance and alertness and change the perception of work effort during exercise. It can also increase motor unit recruitment and muscle contractility making the whole musculoskeletal system work more efficiently. There are also neurotransmitter effects and increases in endorphin release which can increase feelings of wellness, and give you the exercise “high” that people often experience after working out.
Caffeine is effective at quite low doses at around 3 mg per kilogram of body weight. For context, a typical average espresso may contain around 100 mg of caffeine, so two strong cups of coffee could easily get an athlete at or close to the 3 mg per kilogram of body weight figure. Caffeine is rapidly absorbed by most people with peak blood caffeine at around 45 to 90 minutes after taking it.
Sports Dietitians Australian have a great fact sheet on caffeine as well as a table with the caffeine content of an entire range of foods and beverages. No surprise that coffee comes out at the top of the list.
Caffeine’s effects on hydration are likely very much over-stated, especially in habitual consumers (that’s you, coffee addicts). Fluid balance studies showing little impact on hydration at the doses that have been shown to enhance performance. And more so, caffeine is normally consumed with fluid, so this adds to the positive side of the fluid balance equation.
But it’s not all good news when it comes to coffee, so I do need to talk about some the downsides and health risks. And that’s a greater risk of increased heart rate, anxiety and over-arousal, sleep disturbances and gastrointestinal upsets if you take too much of it or are sensitive to it. So, if you are sensitive to caffeine and tend to become overstimulated, you may want to avoid coffee altogether.
Caffeine can also have a blood pressure-raising effect and this spike seems to be stronger in people prone to high blood pressure and who don’t normally drink a lot of coffee. But these acute effects wear off after around 4 hours. What is less clear is caffeine’s long-term effects on blood pressure. The overall long-term effects are inconclusive, but if you do have high blood pressure, it would be best to not over-indulge your caffeine habit.
For women who are pregnant, please take special note with a recent scientific review finding a 37 percent higher risk of miscarriage in women who consume more than 300 mg of caffeine a day. A link between caffeine and the risk of miscarriage has been known for some time which is why FSANZ advises that for pregnant and breastfeeding women daily caffeine consumption should not exceed 200 mg. This is in contrast for non-pregnant adults where 400 mg per day is considered unlikely to cause any harm. This advice is mirrored by similar European and United States regulatory bodies that advise that during pregnancy no more than 200 mg of caffeine should be consumed. That’s about two cups of coffee per day.
What it all means
For regular coffee drinkers, there is little to be concerned about when seeing reports of a single research study indicating coffee is not so good for health. The weight of evidence points to coffee being a healthy habit for adults with the overall weight of scientific evidence saying it will be doing your health more good than harm. It is not a reason to start drinking coffee if you’re not partial to it, but for everyone else, keep calm, keep caffeinated and carry on.