Enjoy that cup of joe without guilt, science says coffee is good for you!

Did you know that people drink around 2 billion cups of coffee every single day? Caffeine is the most popular psychoactive substance on earth, consumed by 80% of humans in the form of coffee or tea.

Given the mind-boggling use of coffee, scientists have been seriously investigating its health effects for decades. Here's what they say.

Back in the 1980s, coffee was commonly viewed as harmful to your health. But, in retrospect, scientists suggest that was because it was often associated with smoking or drinking alcohol.

Now, mounds of research suggest that not only is coffee safe for most people, it has some seriously powerful health benefits.

A 2017 review published in the British Medical Journal (BMJ) looked at 200 different studies and concluded that coffee consumption is safe at normal levels in all cases except for pregnancy.

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The BMJ says between three to four cups a day is the ideal amount to reduce your risk for several diseases.

The same review found the strongest evidence around claims that coffee benefits the liver. The scientists even suggest conducting clinical trials examining coffee as a low-risk treatment for diseases like liver fibrosis, cirrhosis, chronic liver disease, and liver cancer.

Coffee consumption was associated with greater longevity, particularly for those over 54, according to a study that followed 20,000 Spanish volunteers over 10 years and was published in the American Journal of Clinical Nutrition.

The same Spanish study found that more coffee equaled lower mortality, with a 22% lower risk of all-cause mortality for each additional two cups of coffee.

That doesn't mean you should chug it all day, however. "The anti-inflammatory properties of polyphenols together with the inflammatory origins of a wide array of chronic diseases strengthen the biological plausibility of our findings," said the study.

While most health professionals don't recommend sugar, a 2022 Chinese study published in 'Annals of Internal Medicine' found that moderate consumption of both unsweetened and sugar-sweetened coffee was associated with a lower risk of death. However, that wasn't the case for those who drank their cafe with artificial sweeteners.

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Habitual coffee consumption has been associated with a lower risk of type 2 diabetes and cardiovascular diseases, according to a 2019 paper in the European Journal of Nutrition. Those factors can impair agility and diabetics, women and those with obesity who drank at least two cups a day were found to have lower rates of disability.

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Although coffee can temporarily increase blood pressure, the same study found that, contrary to some medical advice, regular coffee drinking may be beneficial for those with hypertension. Another 2021 publication found that 1-3 cups a day does not adversely affect blood pressure in most people.

A study out of the Univerisity of Toronto's Krembil Brain Institute found that coffee could protect you against developing Alzheimer's and Parkinson's disease.

The University of Toronto study, published in 'Frontiers in Neuroscience,' suggests that phenylindanes, which are formed during the roasting of coffee beans, could be what's offering protection against neurological diseases. If that is true, it means dark-roasted coffee offers better protection against Alzheimer's and Parkinson's.

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In contrast, a 2017 Korean study published in 'Journal of Medicinal Food' found that the more coffee beans were roasted, the more they lost their antioxidant and anti-inflammatory effects, which could be beneficial for health.

Roasted coffee contains over 1,000 bioactive compounds that may have beneficial effects, including antioxidants, anti-inflammatories, antifibrotics, and anticancer properties. Some of the main active ingredients in coffee are caffeine, chlorogenic acids, and the diterpenes cafestol and kahweol.

Image: A coffee farmer harvesting coffee berries

If caffeine makes you feel jittery or disrupts your sleep, there's good news: Decaf coffee also has similar health benefits, according to several scientific studies. One Australian study, however, found it helps with overall mortality but didn't reduce the risk of arrhythmia like regular coffee did.

Back in the day, the World Health Organization considered coffee "possibly carcinogenic" due to preliminary evidence linking it to bladder cancer. However, a 2016 paper in The Lancet Oncology concluded that there was "no consistent evidence of a link to coffee consumption" for any cancer.

According to cancer.org, a study looking at data from 1.2 million men and women found that coffee drinkers who didn't smoke had a lower risk of developing colorectal cancer than coffee abstainers.

A 2021 study looked at data from older 365,000 older adults and found that people who drank two to three cups of coffee or tea daily had a 32% lower risk of stroke than people who drank neither beverage. While correlation isn't causation, both coffee and tea contain a range of plant-based compounds called polyphenols, thought to promote healthy blood vessels and dampen inflammation, according to Harvard Health Publishing.

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Do you find yourself reaching for a cup of coffee to boost alertness and mental performance? Well, your body knows what it's doing. A 2016 study found that drinking coffee boosted mental performance in young adults… but only during "non-optimal" times a day — early morning in particular. Another study found that caffeine may boost thinking in the long term.

Photo: European Space Agency ESA/Twitter: Samantha Cristoforetti enjoying the first cup of coffee to be brewed on the Space Station (2015)

Studies have found significant links between coffee consumption and reduced risk of developing depression. However, drinking too much caffeinated coffee can also increase anxiety and even induce panic attacks in people with panic disorder.

The American Pediatric Academy says children under 12 should not drink caffeinated coffee. The US Department of Health says pregnant women should limit consumption to two cups per day, although even moderate consumption has been linked to lower birth size.

A growing amount of scientific evidence also points towards the vital importance of a good night's sleep for health. Caffeine can interfere with sleep, especially when consumed in the evening (if you sleep at night), but not so much when drunk in the morning and afternoon, according to a 2021 review published in Nature.