The health effects of coffee are quite controversial.
Depending on who you ask, it is either a super healthy beverage or incredibly harmful.
But despite what you may have heard, there are actually plenty of good things to be said about coffee.
For example, it is high in antioxidants and linked to a reduced risk of many diseases.
However… it also contains caffeine, a stimulant that can cause problems in some people and disrupt sleep.
This article takes a detailed look at coffee and its health effects, examining both the pros and cons.
Coffee Contains Some Essential Nutrients and is Extremely High in Antioxidants
Coffee is more than just dark brown water… many of the nutrients in the coffee beans do make it into the drink.
A typical 8oz (240 ml) cup of coffee contains (1):
- Vitamin B2 (Riboflavin): 11% of the RDA.
- Vitamin B5 (Pantothenic Acid): 6% of the RDA.
- Vitamin B1 (Thiamin): 2% of the RDA.
- Vitamin B3 (Niacin): 2% of the RDA.
- Folate: 1% of the RDA.
- Manganese: 3% of the RDA.
- Potassium: 3% of the RDA.
- Magnesium: 2% of the RDA.
- Phosphorus: 1% of the RDA.
This may not seem like a lot, but try multiplying with 3, 4, or however many cups you drink per day. It can add up to a significant portion of your daily nutrient intake.
But where coffee really shines is in its high content of antioxidants.
The average person who eats a typical Western diet actually gets more antioxidants from coffee than fruits and vegetables… combined (2, 3).
Bottom Line: Coffee contains a small amount of some vitamins and minerals, which add up if you drink many cups per day. It is also high in antioxidants.
Coffee Contains Caffeine, A Stimulant That Can Enhance Brain Function and Boost Metabolism
Soft drinks, tea and chocolate all contain caffeine, but coffee is the biggest source.
The caffeine content of a single cup can range from 30-300 mg, but the average cup is somewhere around 90-100 mg.
Caffeine is a known stimulant. In the brain, it blocks the function of an inhibitory neurotransmitter (brain hormone) called Adenosine.
By blocking adenosine, caffeine actually increases activity in the brain and the release of other neurotransmitters like norepinephrine and dopamine. This reduces tiredness and makes us feel more alert (5, 6).
There are numerous studies showing that caffeine can lead to a short-term boost in brain function… including improved mood, reaction time, vigilance and general cognitive function (7, 8).
Caffeine can also boost metabolism (calories burned) by 3-11% and even increase exercise performance by 11-12%, on average (9, 10, 11, 12).
However… some of these effects are likely to be short-term. If you drink coffee every day, then you will build a tolerance to it and the effects will be less powerful (13).
There are also some downsides to caffeine, which I’ll get to in a bit.
Bottom Line: The main active compound in coffee is the stimulant caffeine. It can cause a short-term boost in energy levels, brain function, metabolic rate and exercise performance.
Coffee May Help Protect Your Brain in Old Age, Leading to Reduced Risk of Alzheimer’s and Parkinson’s
Alzheimer’s disease is the most common neurodegenerative disease and a leading cause of dementia.
Studies have shown that coffee drinkers have up to a 65% lower risk of developing Alzheimer’s disease (14, 15, 16).
Parkinson’s is the second most common neurodegenerative disease and caused by the death of dopamine-generating neurons in the brain.
Coffee drinkers have a 32-60% lower risk of Parkinson’s disease. The more coffee people drink, the lower the risk (17, 18, 19, 20).
Bottom Line: Several studies show that coffee drinkers have a much lower risk of dementia, Alzheimer’s disease and Parkinson’s disease in old age.
Coffee Drinkers Have a Much Lower Risk of Type 2 Diabetes
Type 2 diabetes is characterized by elevated blood sugars due to resistance to the effects of insulin.
This is a very common disease… it has increased 10-fold in a few decades and now afflicts over 300 million people.
Interestingly, coffee drinkers appear to have a significantly reduced risk of developing this disease, some studies showing that coffee drinkers are up to 23-67% less likely to become diabetic (21, 22, 23, 24).
In one large review study that looked at 18 studies with 457,922 individuals, each daily cup of coffee was linked to a 7% reduced risk of type 2 diabetes (25).
Bottom Line: Numerous studies have shown that coffee drinkers have a significantly lower risk of developing type 2 diabetes.
Coffee Drinkers Have a Lower Risk of Liver Diseases
The liver is an incredibly important organ that has hundreds of different functions in the body.
It is very sensitive to modern insults like excess alcohol and fructose intake.
The end stage of liver damage is called Cirrhosis, and involves most of the liver being replaced with scar tissue.
Coffee drinkers have up to an 84% lower risk of developing cirrhosis, with the strongest effect for those who drink 4 or more cups per day (26, 27, 28).
Liver cancer is also common… it is the second leading cause of cancer death worldwide. Coffee drinkers have up to a 40% lower risk of liver cancer (29, 30).
Bottom Line: Coffee drinkers have a significantly lower risk of cirrhosis and liver cancer. The more coffee they drink, the lower the risk.
People Who Drink Coffee Are at a Much Lower Risk of Depression and Suicide
Depression is an incredibly common problem.
It is the world’s most common mental disorder and leads to a significantly reduced quality of life.
In one Harvard study from 2011, people who drank the most coffee had a 20% lower risk of becoming depressed (31).
In one review of 3 studies, people who drank 4 or more cups of coffee per day were 53% less likely to commit suicide (32).
Bottom Line: Studies have shown that people who drink coffee have a lower risk of becoming depressed and are significantly less likely to commit suicide.
Some Studies Show That Coffee Drinkers Live Longer
Given that coffee drinkers have a lower risk of many common, deadly diseases (and suicide), it makes sense that coffee could help you live longer.
There is actually some good evidence to support this.
A study published in the New England Journal of Medicine in 2012 looked at the habits of 402,260 individuals between 50 and 71 years of age (33).
In this study, people who drank coffee had a much lower risk of dying over the 12-13 year study period:
The sweet spot seems to be at 4-5 cups per day, with men having a 12% reduced risk and women a 16% reduced risk.
You can read more about it in this article on how coffee can make you live longer.
Bottom Line: Some studies have shown that coffee drinkers live longer, which makes perfect sense given that they have a lower risk of many diseases. The strongest effect is seen for 4-5 cups per day.
Caffeine Can Cause Anxiety and Disrupt Sleep
It wouldn’t be right to only talk about the good stuff without mentioning the bad.
The truth is… there are some important negative aspects to coffee as well (although this depends on the individual).
Consuming too much caffeine can lead to jitteriness, anxiety, heart palpitations and may even exacerbate panic attacks (34).
If you are sensitive to caffeine and tend to become overstimulated, then perhaps you shouldn’t be drinking coffee.
Another unwanted side effect is that it can disrupt sleep (35). If coffee reduces the quality of your sleep, then try avoiding coffee late in the day, such as after 2pm.
Caffeine can also have some diuretic and blood pressure raising effects, but this usually goes away with regular use. However, an increase in blood pressure of 1-2 mm/Hg may persist (36, 37, 38).
Bottom Line: Caffeine can have various negative effects, such as causing anxiety and disrupting sleep, but this depends greatly on the individual.
Caffeine is Addictive and Missing a Few Cups Can Lead to Withdrawal
One issue with caffeine, is that it can lead to addiction in many people.
When people consume caffeine regularly, they become tolerant to it. It either stops working as it used to, or a larger dose is needed to get the same effects (39).
When people abstain from caffeine, they get withdrawal symptoms like headache, tiredness, brain fog and irritability. This can last for a few days (40, 41).
Tolerance and withdrawal are the hallmarks of physical addiction.
A lot of people (understandably) don’t like the idea of being literally dependant on a chemical substance in order to function properly.
Bottom Line: Caffeine is an addictive substance. It can lead to tolerance and well documented withdrawal symptoms like headache, tiredness and irritability.