The health effects of coffee include various possible health benefits and health risks. [1]
A 2017 umbrella review of meta-analyses found that drinking coffee is generally safe within usual levels of intake and is more likely to improve health outcomes than to cause harm at doses of 3 or 4 cups of coffee daily. Exceptions include possible increased risk in women having bone fractures, and a possible increased risk in fetal loss or decreased birth weight during pregnancy. [2] Results were complicated by poor study quality, and differences in age, gender, health status, and serving size. [2]
A 1999 review found that coffee does not cause indigestion, but may promote gastrointestinal reflux. [3] Two reviews of clinical studies on people recovering from abdominal, colorectal, and gynecological surgery found that coffee consumption was safe and effective for enhancing postoperative gastrointestinal function. [4] [5]
In some people, coffee induces defecation within minutes of consumption. [5] [6] [7] [8] However, the specific mechanism of action and chemical constituents responsible are still unknown. [9]
A 2014 meta-analysis found that coffee consumption (4 cups/day) was inversely associated with all-cause mortality (a 16% lower risk), as well as cardiovascular disease mortality specifically (a 21% lower risk from drinking 3 cups/day), but not with cancer mortality [10] with exception being oral cancer mortality. [11]
Additional meta-analyses corroborated these findings, showing that higher coffee consumption (2–4 cups per day) was associated with a reduced risk of death by all disease causes. [12] [13]
Moderate coffee consumption is not a risk factor for coronary heart disease. [14]
A 2012 meta-analysis concluded that people who drank moderate amounts of coffee had a lower rate of heart failure, with the biggest effect found for those who drank more than four cups a day. [15] A 2014 meta-analysis concluded that cardiovascular disease, such as coronary artery disease and stroke, is less likely with three to five cups of non-decaffeinated coffee per day, but more likely with over five cups per day. [16] A 2016 meta-analysis showed that coffee consumption was associated with a reduced risk of death in patients who have had a myocardial infarction. [17] The effect of no or moderate daily consumption of coffee on risk for developing hypertension has been assessed in several reviews during the 21st century. A 2019 review found that one to two cups consumed per day had no effect on hypertension risk, whereas drinking three or more cups per day reduced the risk, [18] a finding in agreement with a 2017 analysis which showed a 9% lower risk of hypertension with long-term consumption of up to seven cups of coffee per day. [19] Another review in 2018 found that the risk of hypertension was reduced by 2% with each one cup per day increment of coffee consumption up to 8 cups per day, compared with people who did not consume any coffee. [20]
A large 2024 study, [21] involving close to two hundred thousand participants using the UK Biobank, indicated that a habitual caffeine intake, at moderate levels of 200 mg - 300 mg of caffeine per day "was associated with a lower risk of new-onset CM [Cardiometabolic multimorbidity] and could play important roles in almost all transition phases of CM development." In particular, the study found that metabolites related to very low-density lipoproteins were reduced with higher metabolites related to high-density lipoproteins. The study found any caffeine intake in general reduced risks of CM, although did not find strong evidence that tea reduced the risk of stroke and Type 2 Diabetes.
By contrast, a 2011 review had found that drinking one to three cups of coffee per day may pose a slightly increased risk of developing hypertension. [22]
The 2021 European Society of Cardiology Guidelines on Cardiovascular Disease Prevention in Clinical Practice state: "Non-filtered coffee contains LDL-C-raising cafestol and kahweol, and may be associated with an up to 25% increased risk of atherosclerosis (ASCVD) mortality by consumption of nine or more drinks a day. Non-filtered coffee includes boiled, Greek, and Turkish coffee and some espresso coffees. Moderate coffee consumption (3–4 cups per day) is probably not harmful, perhaps even moderately beneficial". [23]
Meta-analyses have consistently found that long-term coffee consumption is associated with a lower risk of Parkinson's disease. [2]
In a systematic review and meta-analysis of 28 prospective observational studies, representing over one million participants, every additional cup of caffeinated and decaffeinated coffee consumed in a day was associated, respectively, with a 9% and 6% lower risk of type 2 diabetes. [24]
Meta-analyses on the effects of coffee consumption on cancer risk are inconclusive. [25] [26] [27]
The World Health Organization's 2016 IARC Monograph "found no conclusive evidence for a carcinogenic effect of drinking coffee" but found that drinking very hot beverages probably causes cancer of the oesophagus. [28]
According to The British Liver Trust, regular consumption of coffee may support liver health and reduce the risk of some liver diseases. [29]
The UK National Health Service advises that avoiding coffee may reduce anxiety. [30] In chronic psychiatric patients, caffeine, the major active ingredient in coffee, is associated with anxiety. [31] [32] At high doses, typically greater than 300 mg, caffeine can both cause and worsen anxiety. [33] For some people, discontinuing caffeine use can significantly reduce anxiety. [34] Caffeine-induced anxiety disorder is a subclass of substance- or medication-induced anxiety disorder. [35] Populations that may be most impacted by caffeine consumption are adolescents and people with anxiety disorders. [36] Preliminary research indicated the possibility of a beneficial relationship between coffee intake and reduced depression. [2] [37] [38] Long-term preliminary research, including assessment of symptoms for dementia and cognitive impairment, was inconclusive for coffee having an effect in the elderly, mainly due to the poor quality of the studies. [2] [39]
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class and is the most commonly consumed psychoactive substance globally. It is mainly used for its eugeroic, ergogenic, or nootropic (cognitive-enhancing) properties. Caffeine acts by blocking binding of adenosine at a number of adenosine receptor types, inhibiting the centrally depressant effects of adenosine and enhancing the release of acetylcholine. Caffeine has a three-dimensional structure similar to that of adenosine, which allows it to bind and block its receptors. Caffeine also increases cyclic AMP levels through nonselective inhibition of phosphodiesterase, increases calcium release from intracellular stores, and antagonizes GABA receptors, although these mechanisms typically occur at concentrations beyond usual human consumption.
Stimulants are a class of drugs that increase alertness. They are used for various purposes, such as enhancing attention, motivation, cognition, mood, and physical performance. Some stimulants are naturally-occuring while others only occur synthetic. Some of the most common stimulants are caffeine, nicotine, amphetamines, cocaine, methylphenidate, and modafinil. Stimulants may be subject to varying forms of regulation, or outright prohibition, depending on jurisdiction.
Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, vision loss, chronic kidney disease, and dementia. Hypertension is a major cause of premature death worldwide.
Type 2 diabetes (T2D), formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, fatigue and unexplained weight loss. Other symptoms include increased hunger, having a sensation of pins and needles, and sores (wounds) that heal slowly. Symptoms often develop slowly. Long-term complications from high blood sugar include heart disease, stroke, diabetic retinopathy, which can result in blindness, kidney failure, and poor blood flow in the lower-limbs, which may lead to amputations. The sudden onset of hyperosmolar hyperglycemic state may occur; however, ketoacidosis is uncommon.
The long-term effects of alcohol have been extensively researched. The health effects of long-term alcohol consumption on health vary depending on the amount consumed. Even light drinking poses health risks, but atypically small amounts of alcohol may have health benefits. Alcoholism causes severe health consequences which outweigh any potential benefits.
The Mediterranean diet is a concept first invented in 1975 by the American biologist Ancel Keys and chemist Margaret Keys. The diet took inspiration from the eating habits and traditional food typical of Crete, much of the rest of Greece, and southern Italy, and formulated in the early 1960s. It is distinct from Mediterranean cuisine, which covers the actual cuisines of the Mediterranean countries, and from the Atlantic diet of northwestern Spain and Portugal. While inspired by a specific time and place, the "Mediterranean diet" was later refined based on the results of multiple scientific studies.
Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, arrhythmia, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis.
A multivitamin is a preparation intended to serve as a dietary supplement with vitamins, dietary minerals, and other nutritional elements. Such preparations are available in the form of tablets, capsules, pastilles, powders, liquids, gummies, or injectable formulations. Other than injectable formulations, which are only available and administered under medical supervision, multivitamins are recognized by the Codex Alimentarius Commission as a category of food.
The health effects of tea have been studied throughout human history. In clinical research conducted over the early 21st century, tea has been studied extensively for its potential to lower the risk of human diseases, but there is no good scientific evidence to support any therapeutic uses other than possibly increasing alertness, an effect caused by caffeine in the tea leaves.
A plant-based diet is a diet consisting mostly or entirely of plant-based foods. It encompasses a wide range of dietary patterns that contain low amounts of animal products and high amounts of fiber-rich plant products such as vegetables, fruits, whole grains, legumes, nuts, seeds, herbs, and spices. Plant-based diets may also be vegan or vegetarian but do not have to be, as they are defined in terms of high frequency of plants and low frequency of animal food consumption.
Recurrent miscarriage or recurrent pregnancy loss (RPL) is the spontaneous loss of 2-3 pregnancies that is estimated to affect up to 5% of women. The exact number of pregnancy losses and gestational weeks used to define RPL differs among medical societies. In the majority of cases, the exact cause of pregnancy loss is unexplained despite genetic testing and a thorough evaluation. When a cause for RPL is identified, almost half are attributed to a chromosomal abnormality. RPL has been associated with several risk factors including parental and genetic factors, congenital and acquired anatomical conditions, lifestyle factors, endocrine disorders, thrombophila, immunological factors, and infections. The American Society of Reproductive Medicine recommends a thorough evaluation after 2 consecutive pregnancy losses; however, this can differ from recommendations by other medical societies. RPL evaluation can be evaluated by numerous tests and imaging studies depending on the risk factors. These range from cytogenetic studies, blood tests for clotting disorders, hormone levels, diabetes screening, thyroid function tests, sperm analysis, antibody testing, and imaging studies. Treatment is typically tailored to the relevant risk factors and test findings. RPL can have a significant impact on the psychological well-being of couples and has been associated with higher levels of depression, anxiety, and stress. Therefore, it is recommended that appropriate screening and management be considered by medical providers.
Caffeine dependence is a condition characterized by a set of criteria, including tolerance, withdrawal symptoms, persistent desire or unsuccessful efforts to control use, and continued use despite knowledge of adverse consequences attributed to caffeine. It can appear in physical dependence or psychological dependence, or both. Caffeine is one of the most common additives in many consumer products, including pills and beverages such as caffeinated alcoholic beverages, energy drinks, pain reliever medications, and colas. Caffeine is found naturally in various plants such as coffee and tea. Studies have found that 89 percent of adults in the U.S. consume on average 200 mg of caffeine daily. One area of concern that has been presented is the relationship between pregnancy and caffeine consumption. Repeated caffeine doses of 100 mg appeared to result in smaller size at birth in newborns. When looking at birth weight however, caffeine consumption did not appear to make an impact.
In a 2018 study on 599,912 drinkers, a roughly linear association was found with alcohol consumption and a higher risk of stroke, coronary artery disease excluding myocardial infarction, heart failure, fatal hypertensive disease, and fatal aortic aneurysm, even for moderate drinkers. Alcohol abuse may also cause occupational cardiovascular disease. The American Heart Association states that people who are currently non-drinkers should not start drinking alcohol.
Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension and diabetes throughout life.
Alcohol has a number of effects on health. Short-term effects of alcohol consumption include intoxication and dehydration. Long-term effects of alcohol include changes in the metabolism of the liver and brain, with increased risk of several types of cancer and alcohol use disorder. Alcohol intoxication affects the brain, causing slurred speech, clumsiness, and delayed reflexes. There is an increased risk of developing an alcohol use disorder for teenagers while their brain is still developing. Adolescents who drink have a higher probability of injury including death.
Perindopril is a medication used to treat high blood pressure, heart failure, or stable coronary artery disease. As a long-acting ACE inhibitor, it works by relaxing blood vessels and decreasing blood volume. As a prodrug, perindopril is hydrolyzed in the liver to its active metabolite, perindoprilat. It was patented in 1980 and approved for medical use in 1988.
Many dietary recommendations have been proposed to reduce the risk of cancer, few have significant supporting scientific evidence. Obesity and drinking alcohol have been correlated with the incidence and progression of some cancers. Lowering the consumption of sweetened beverages is recommended as a measure to address obesity.
Caffeine-induced sleep disorder was a psychiatric disorder identified as resulting from overconsumption of the stimulant caffeine.
Sugar-sweetened beverages (SSB) are beverages with added sugar. They have been described as "liquid candy". Added sugars include brown sugar, corn sweetener, corn syrup, dextrose, fructose, high fructose corn syrup, honey, invert sugar, lactose, malt syrup, maltose, molasses, raw sugar, sucrose, trehalose, and turbinado sugar. Naturally occurring sugars, such as those in fruit or milk, are not considered to be added sugars. Free sugars include monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.
Frank B. Hu is a Chinese American nutrition and diabetes researcher. He is Chair of the Department of Nutrition and the Fredrick J. Stare Professor of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, and Professor of Medicine at the Harvard Medical School.