Caffeine, the psycho-active stimulant in coffee, is the most popular drug in the world. Coffee is one of the most popular drinks in the world. Coffee beans are the second most traded commodity globally, after oil. The world’s three biggest producers are Brazil, followed by Vietnam and Colombia. The biggest consumer of coffee is the USA. Human beings have a strong attachment to coffee!
Globally, there have been multiple small studies on the effects of caffeine over the years. However, given how widespread coffee consumption is worldwide, it’s surprising how few major research studies have been conducted into the health effects of drinking coffee and in particular caffeine.
Caffeine and Sleep
By far the greatest detrimental health effect of caffeine consumption is the way it impairs the quality of your sleep. Dr Rangan Chatterjee on his YouTube channel explored this when he interviewed Professor Matthew Walker, a world-leading sleep researcher. From this interview we learn that one cup of caffeinated coffee in the evening reduces deep sleep by 20%. Deep sleep is vital for long term health, because of its restorative effects on the body and mind.
Drinking caffeinated coffee after midday has the most adverse effects on sleep, due to the long half-life (6 hours) of caffeine. A six-hour half-life means that half the caffeine you drink is still in your system after six hours. Caffeine also has a quarter-life of 12 hours, which means that if you drink a cup of caffeinated coffee at noon, a quarter of the caffeine is still in your system at midnight, enough to disrupt your sleep.
Why does caffeine disrupt deep sleep? In short, because it is a powerful stimulant. It makes you more alert, potentially more anxious and jittery. After the initial dopamine high, the stress hormone cortisol is triggered, together with the “fight or flight” chemical epinephrine (more commonly known as adrenaline). This is not a conducive state to be in for a good night’s sleep.
How much coffee can you safely drink to avoid adverse sleep effects? The latest science is that 400mg is a safe maximum, which is around 3 regular cups of coffee, as long as you restrict your consumption to the mornings.
I had a personal training client in north London who told me when we first met for the initial consultation that he had major problems sleeping and felt tired all the time. When I asked how much coffee he drank each day, he replied 8 cups. I recommended he reduce this to two cups in the morning and none in the afternoon or evening. After following this advice, within a week his sleep had dramatically improved and he felt far more energized throughout the day. Amazing!
A good alternative to caffeinated coffee is decaf coffee. Decaffeination removes approx 97% of the caffeine, so you won’t get the sleep problems caused by caffeinated coffee. Tea contains approx 50mg of caffeine (compared to approx 130mg in a regular cup of coffee). Mint tea contains zero caffeine, as does camomile tea.
Caffeine and Chronic Fatigue
Because caffeine wrecks your sleep, drinking caffeinated coffee over a long period results in chronic fatigue, sometimes called “tired all the time syndrome”. Caffeine tricks your mind into thinking it’s giving you energy, but it’s fake energy. The caffeine stimulates the release of the neurotransmitter dopamine, which gives you a high, and starts to form an addiction to that good feeling. This is why people find it hard to quit caffeine.
Chronic fatigue caused by caffeine and the resulting poor sleep can lock you into a vicious cycle. You wake up tired, and drink caffeinated coffee to give you a kick-start. During the day fatigue keeps returning, so you self-medicate with caffeine to stimulate you. However, this guarantees a bad night’s sleep, and the vicious cycle resumes the next day. Many of my personal training clients in London have high-powered jobs which demand a high level of concentration over many hours, so they drink lots of caffeinated coffee to power them through their punishing workload.
The only way to break out of this vicious cycle of self-sabotage is to quit drinking coffee after midday, to drink only 2 cups in the morning, and ideally switch to decaffeinated coffee.
Caffeine and Gastro-Intestinal Disorders
The good news for coffee-lovers is that there is an inconclusive relationship between coffee consumption and gastro-intestinal disorders (which cover a wide range of conditions ranging from GERD, also known as acid-reflux; to stomach/duodenal ulcers, and the inflammatory bowel disorders such as irritable bowel syndrome, ulcerative colitis and Crohn’s disease).
However, I’m not saying that caffeine is never a problem for people with any of the above disorders. If you have any of these conditions, seek the advice of your doctor, don’t treat this blog post as medical advice. Some people find caffeine has an inflammatory effect on their stomach, duodenum, small intestines or bowel, in which case avoid it.
By far the greatest proven causes of gastro-intestinal disorders are things like obesity, high levels of stress, alcohol consumption, highly-spiced food (the strongest chilli peppers), fried-food, junk food, and the heliobacter pylori bacterial infection.
Health Risks of Acrylamide in Coffee
There is a chemical compound in roasted coffee beans called acrylamide which is toxic in large quantities, Studies have linked this compound to diseases such as periphoral neuropathy (nerve-damage), and neural degeneracy (such as Alzheimer’s and Parkinson’s disease). There is no evidence that moderate coffee consumption contributes to these diseases, but heavy consumption is a risk-factor. Nor is there any evidence of coffee consumption having any carcinogenic effects.
Health Benefits of Coffee
Provided you restrict your coffee-consumption to the mornings, and don’t exceed 3 regular cups a day, there are a number of health benefits of coffee drinking. Studies have shown that drinking up to 3 cups of coffee a day can reduce risk of Alzheimer’s disease, liver cancer, pancreatitis and pancreatic cancer, and coronary heart disease (CHD). Polyphenols in coffee are thought to be responsible for these positive health effects. Polyphenols are compounds found in plants which have antioxidant and anti-inflammatory effects.
Coffee in moderation can also improve the health of your gut microbiome (your gut bacteria), thanks to its stimulation of one of the friendly gut bacteria called bifidobacterium.
Caffeinated coffee has also been found to stimulate the motor activity of the colon, which in layman’s terms means that it helps you evacuate your bowel, so it can help relieve constipation. However, the root cause of constipation should be addressed, such as too little fibre in your diet or dehydration. Bear in mind that coffee is a mild diuretic, so make sure you drink plenty of water throughout the day to stay hydrated.
You retain all the health benefits of coffee if you switch to decaf, so drinking decaf coffee is a win-win.
(Dominic Londesborough is a personal trainer in London and an online nutrition coach)