The health effects of coffee include various 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] An association of coffee drinking with reduced risk for death from various sources was confirmed by a widely cited prospective cohort study of ten European countries in 2017. [14]
Moderate coffee consumption is not a risk factor for coronary heart disease. [15] 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. [16] 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. [17] A 2016 meta-analysis showed that coffee consumption was associated with a reduced risk of death in patients who have had a myocardial infarction. [18]
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, [19] 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. [20] 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. [21] 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 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]
The Women's Health Study showed an increased risk of atrial fibrillation with 2–3 cups/day of caffeinated coffee, [24] but other studies found either no effect or a protective effect. [25]
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. [26]
Research on the effects of coffee consumption on cancer risk generally has indicated no effect [27] [28] or a slightly lower risk of cancer, particularly in the liver. [29] [30]
Preliminary evidence indicates that coffee consumption may be protective against the progression of liver disease, although the possible mechanisms for such an effect remain unclear. [31]
The UK National Health Service advises that avoiding coffee may reduce anxiety. [32] In chronic psychiatric patients, caffeine, the major active ingredient in coffee, is associated with anxiety. [33] [34] At high doses, typically greater than 300 mg, caffeine can both cause and worsen anxiety. [35] For some people, discontinuing caffeine use can significantly reduce anxiety. [36] Caffeine-induced anxiety disorder is a subclass of substance- or medication-induced anxiety disorder. [37] Populations that may be most impacted by caffeine consumption are adolescents and those already suffering anxiety disorders. [38] Preliminary research indicated the possibility of a beneficial relationship between coffee intake and reduced depression. [2] [39] [40] 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] [41]
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used as a eugeroic (wakefulness promoter) or as a mild cognitive enhancer to increase alertness and attentional performance. Caffeine acts by blocking binding of adenosine to the adenosine A1 receptor, which enhances release of the neurotransmitter 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.
Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitamin E, can cause nerve problems. Vitamin E is a fat-soluble antioxidant which may help protect cell membranes from reactive oxygen species. Worldwide, government organizations recommend adults consume in the range of 3 to 15 mg per day. As of 2016, consumption was below recommendations according to a worldwide summary of more than one hundred studies that reported a median dietary intake of 6.2 mg per day for alpha-tocopherol.
The health effects of long-term alcohol consumption on health vary depending on the amount of ethanol consumed. Even light drinking poses health risks, but small amounts of alcohol may also have health benefits. Chronic heavy drinking causes severe health consequences which outweigh any potential benefits.
The Mediterranean diet is a diet inspired by the eating habits and traditional food typical of southern Spain, southern Italy, and Crete, and formulated in the early 1960s. It is distinct from Mediterranean cuisine, which covers the actual cuisines of the Mediterranean countries. 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, 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.
Although health benefits have been assumed throughout the history of using Camellia sinensis as a common beverage, there is no high-quality evidence that consuming tea confers significant benefits other than possibly increasing alertness, an effect caused by caffeine in the tea leaves. 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 indicate that consuming tea affects any disease or improves health.
A plant-based diet is a diet consisting mostly or entirely of plant-based foods. Plant-based diets encompass 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 and seeds. They do not need to be vegan or vegetarian but are defined in terms of low frequency of animal food consumption.
Weight cycling, also known as yo-yo dieting, is the repeated loss and gain of weight, resembling the up-down motion of a yo-yo. The purpose of the temporary weight loss the yo-yo diet delivers is to lure the dieting into the illusion of success, but due to the nature of the diet, they are impossible to sustain, therefore the dieter gives up, often due to hunger or discomfort, and gain the weight back. The dieter then seeks to lose the regained weight, and the cycle begins again. Other individuals cycle weight deliberately in service of bodybuilding or athletic goals. Weight cycling contributes to increased risk of later obesity, due to repeated signals being sent to the body signalling that it's in starvation mode; therefore it learns to be better and better at storing fat, and increases the strain on vital organs, likely promoting cardiometabolic disease.
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 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.
In gastronomy, red meat is commonly red when raw, in contrast to white meat, which is pale in color before cooking. In culinary terms, only flesh from mammals or fowl is classified as red or white. In nutritional science, red meat is defined as any meat that has more of the protein myoglobin than white meat. White meat is defined as non-dark meat from fish or chicken.
Excessive alcohol intake is associated with an elevated risk of alcoholic liver disease (ALD), heart failure, some cancers, and accidental injury, and is a leading cause of preventable death in industrialized countries. Some studies have suggested that one drink per day may have cardiovascular benefits. However, these studies are controversial, and the common view is that no level of alcohol consumption improves health. There is far more evidence for the harmful effects of alcohol than for any beneficial effects. It is also recognized that the alcohol industry may promote the unsubstantiated benefits of moderate drinking.
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.
The health effects of wine are mainly determined by its active ingredient – alcohol. Preliminary studies found that drinking small quantities of wine, particularly of red wine, may be associated with a decreased risk of cardiovascular diseases, cognitive decline, stroke, diabetes mellitus, metabolic syndrome, and early death. Other studies found no such effects.
Megavitamin therapy is the use of large doses of vitamins, often many times greater than the recommended dietary allowance (RDA) in the attempt to prevent or treat diseases. Megavitamin therapy is typically used in alternative medicine by practitioners who call their approach orthomolecular medicine. Vitamins are useful in preventing and treating illnesses specifically associated with dietary vitamin shortfalls, but the conclusions of medical research are that the broad claims of disease treatment by advocates of megavitamin therapy are unsubstantiated by the available evidence. It is generally accepted that doses of any vitamin greatly in excess of nutritional requirements will result either in toxicity or in the excess simply being metabolised; thus evidence in favour of vitamin supplementation supports only doses in the normal range. Critics have described some aspects of orthomolecular medicine as food faddism or even quackery. Research on nutrient supplementation in general suggests that some nutritional supplements might be beneficial, and that others might be harmful; several specific nutritional therapies are associated with an increased likelihood of the condition they are meant to prevent.
Dietary factors are recognized as having a significant effect on the risk of cancers, with different dietary elements both increasing and reducing risk. Diet and obesity may be related to up to 30–35% of cancer deaths, while physical inactivity appears to be related to 7% risk of cancer occurrence.
Caffeine-induced sleep disorder is a psychiatric disorder that results from overconsumption of the stimulant caffeine. Caffeine is one of the most widely consumed psychoactive drugs: almost 90% of Americans in a survey consume some type of caffeine each day. "When caffeine is consumed immediately before bedtime or .... throughout the day, sleep onset may be delayed, total sleep time reduced, normal stages of sleep altered, and the quality of sleep decreased." Caffeine reduces slow-wave sleep in the early part of the sleep cycle and can reduce rapid eye movement sleep later in the cycle. Caffeine increases episodes of wakefulness, and high doses in the late evening can increase sleep onset latency. In elderly people, there is an association between use of medication containing caffeine and difficulty in falling asleep.
Humans and their hominid ancestors have consumed eggs for millions of years. The most widely consumed eggs are those of fowl, especially chickens. People in Southeast Asia began harvesting chicken eggs for food by 1500 BCE. Eggs of other birds, such as ducks and ostriches, are eaten regularly but much less commonly than those of chickens. People may also eat the eggs of reptiles, amphibians, and fish. Fish eggs consumed as food are known as roe or caviar.
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.
A non-pharmaceutical intervention or non-pharmacological intervention (NPI) is any type of health intervention which is not primarily based on medication. Some examples include exercise, sleep improvement, or dietary habits.