Caffeine is the most commonly used psychoactive drug in the world - for good reason. It wakes us up, helps us stay on task, and provides an extra energy boost. According to a range of scientific studies, drinking coffee in moderation can also improve your health and prolong your life.
Most people in Australia get their caffeine fix from coffee. But people often worry that they should limit their coffee consumption or cut it out completely. That's probably because coffee can feel like a crutch.
It is possible to overdo it on caffeine -many heavy coffee drinkers surpass the recommended limit of 400 mg of caffeine per day, and that can cause insomnia, restlessness, or a fast heartbeat, especially if consumed too fast.
But most research on coffee consumption indicates that coffee is not bad for us, and is associated with some pretty impressive health benefits. Even people who drink lots of coffee, more than five or six cups a day, seem to be far healthier than people who drink little or none.
In most cases we can't say that coffee actually causes health benefits - the causal mechanism is unclear. But research does suggest that coffee drinkers are less likely to suffer from certain illnesses.
There are plenty of foods and drinks that most of us should consume less. But here's why you shouldn't worry about your coffee habit.
Liver health: A review that combined the results of nine studies found that drinking more coffee is associated with lower risk for cirrhosis.
In the review, drinking one cup of coffee per day was shown to be linked with a 22% reduced risk for cirrhosis, a liver disease that is often caused by heavy alcohol consumption. Two daily cups were associated with a 43% reduced risk, three cups with 57% reduced risk, and four cups with 65% reduced risk.
Heart disease: A review of more than 200 studies found that people who drank three or four cups of coffee per day were 19% less likely to die from cardiovascular disease.
Type 2 diabetes: One large review of studies found that every additional cup of coffee a person drinks per day was correlated with a 7% reduced risk for developing Type 2 diabetes.
Source: JAMA Internal Medicine
Cancer: One review found that heavy coffee drinkers (who had at least three cups a day) had an 18% reduced risk for cancer.
Another review found that at least one cup per day was associated with 15% reduced risk for liver cancer and an 8% reduced risk for endometrial cancer.
Alzheimer's disease and dementia: A meta-analysis of studies about coffee intake and brain health calculated that regular coffee drinkers were approximately 16% less likely to suffer from Alzheimer's, dementia, or cognitive decline.
There are smaller studies that suggest drinking coffee can lead to even bigger risk reductions for Alzheimer's.
Depression: One large study of more than 50,000 women showed that drinking at least a cup of coffee each week was associated with 15% reduced risk for depression, and drinking two to three cups per day was associated with 20% reduced risk.
Another study that looked at more than 100,000 men and women found that coffee drinkers were 45% less likely to die from suicide, and heavy coffee drinkers (those who had four or more cups per day) were 53% less likely to die from suicide.
Overall mortality: A large study of more than 500,000 European people found that in a 16-year-period, men who drank three or more cups per day were 12% less likely to die, and women 7% less likely to die.
In particular, people were less likely to die from circulatory and digestive diseases. Heavy coffee drinkers also had healthier livers.
Another study of 185,855 multi-ethnic Americans confirmed that result. People who drank one cup per day were 12% less likely to die. A coffee intake of two to three cups was associated with an 18% decrease in risk for early death. (Decaf had the same benefits.)
Recently, yet another study of 500,000 people in the UK found that those who drank two to five cups of coffee in a day were about 12% less likely to die than non-coffee-drinkers over the 10-year time period in the study. People who drank six to seven cups were 16% less likely to die, and people who drank eight or more cups were about 14% less likely to die. That study also confirmed that people whose genetics make them slow to process caffeine still get the same benefits.