Coffee

Studies in people

• Open question

  Heart health³

  Moderate coffee drinking is linked to lower risk of heart problems, though unfiltered coffee may raise cholesterol.

• Benefit

  Brain and mood effects⁴

  Coffee can boost alertness, concentration and mood, and may lower risk of stroke and Parkinson's disease.

• Benefit

  Kidney stones⁵

  In genetic studies, higher coffee and caffeine consumption may cause a lower risk of kidney stones.

• Benefit

  Belly fat and body weight⁶

  Studies in people link drinking more coffee to slightly less body fat, especially in men.

• Benefit

  Dementia risk and memory⁷

  In adults, drinking caffeinated coffee was linked to lower dementia risk and slightly better cognitive test scores.

• Benefit

  Morning drinking and survival⁸

  In adults, drinking coffee mainly in the morning was linked to a lower risk of death than not drinking coffee.

• Concern

  Heart rhythm⁹

  In people, drinking caffeinated coffee was linked to more extra heartbeats and less sleep.

• Benefit

  Heart and liver health¹¹

  Drinking coffee is linked to lower risks of heart disease, liver disease and some cancers, but most studies only observe people.

• Open question

  Blood fats¹²

  In people, coffee changed some blood fats called LPCs, but what this means for health is not yet known.

• Benefit

  Kidney disease risk¹³

  People who drank more coffee were less likely to have chronic kidney disease, though this link isn't proof of cause.

• Open question

  Breast density in women¹⁴

  In premenopausal women, drinking coffee daily was not linked to breast density overall, though one measure rose in Black women.

• No harm found

  Epilepsy risk¹⁵

  Genetically predicted coffee intake was not related to epilepsy risk, the study found.

• Benefit

  Thinking and memory in illness¹⁶

  In people with HIV and hepatitis C, drinking three or more cups of coffee a day was linked to better thinking skills.

• Open question

  Blood cholesterol levels¹⁷

  People who drank more coffee tended to have higher cholesterol, though diet may explain the link.

• Benefit

  Hearing loss risk¹⁸

  In men, drinking coffee was linked to a lower risk of hearing loss, but not in women.

• No harm found

  Upset stomach and indigestion¹⁹

  In 3,362 Iranian adults, coffee and caffeine intake was not linked to indigestion or its symptoms.

• Benefit

  Bowel cancer risk²⁰

  People who drank the most coffee were less likely to develop colorectal cancer, though scientists say more research is needed.

• Benefit

  Disability in older adults²¹

  In older Japanese adults, those who drank more coffee were less likely to become disabled or die.

Animal and lab studies only

• Open question

  Gut and brain health²⁷

  In lab studies, coffee affected the gut lining, gut movement, and the gut-brain connection, but much is still unknown.

Study type not stated

• Benefit

  Heart and brain health²²

  Coffee's natural compounds may help protect against heart, brain and liver problems, though scientists are still learning how.

• Benefit

  Heart and diabetes risk²⁴

  Coffee's chlorogenic acids are linked to lower risk of heart disease and type 2 diabetes.

• Benefit

  Fat storage and obesity²⁵

  Coffee and its plant molecules may help reduce fat storage, though scientists do not yet know the full picture.

• Open question

  Brewing transfer of contaminants²⁶

  Coffee beans and powder contain mineral oil hydrocarbons, but less than 5% gets into your brewed cup.

Found in some samples or products

These come from where it was grown, how it was processed or cooked, or what it was made into. They are not about the ingredient itself, so the signal does not count them.

• Chemicals formed by roasting²³

  Roasting coffee can form acrylamide, furan and other chemicals, and scientists do not yet know the real risk to people.

How it’s made and used

• Appetite and food intake²

  In studies, coffee before a meal had little effect on how much people ate, but caffeine may lower it.

• Gut bacteria¹⁰

  Coffee feeds a specific gut germ called Lawsonibacter asaccharolyticus, and scientists found this same link in thousands of people.

• Bitter taste receptors²⁸

  Mozambioside, cafestol and kahweol in coffee switch on two human bitter taste sensors.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.

Expert panels that weigh all the research. Shown for context: the signal at the top does not count them. IARC rates whether something can cause cancer at all, not how likely it is at the amounts in food.

• WHO cancer agency (IARC), 2016

  For drinking coffee: not enough evidence to say whether it causes cancer in people (Group 3).