Flatulence
Too much coffee is considered to cause gas
Diabetes mellitus / insulin resistance
There is some evidence that caffeine may affect insulin sensitivity in the short term. However, this effect could not be confirmed for the consumption of coffee. The risk of developed type 2 diabetes mellitus even decreases with moderate consumption. It is still unclear whether other drink ingredients are decisive or whether habituation effects affect.
Lipid metabolism disorders
Only the cafestol in coffee can slightly increase the LDL blood concentrations [ Dam 2020 ]. Cafestol is found in significant quantities in unfiltered coffee beverages. However, there is no information on the extent to which the substance affects the LDL particle size. However, the LDL molecules' size and density affect the cardiovascular risk, not the LDL cholesterol level itself.
Gallstones
Coffee affects several processes related to gallstone formation. It promoted cholecystokinin's release and the gallbladder's contraction and suppressed the formation of cholesterol stones in animal experiments.
In the Nurses' Health Study and the Health Professionals Follow-Up Study, gallstones were less common in regular coffee drinkers than in abstainers. According to the scientists' calculations, consuming two or more coffee cups a day reduced the gallstone risk in men by 40 to 45% and in women by 22 to 28%. Decaffeinated coffee showed no effect, so that the protective effect may be due to the alkaloid caffeine. When evaluating such retrospective studies, however, the possibility must also be taken into account that people with symptomatic gallstones may have avoided coffee because of symptoms. The low coffee consumption was not associated with the occurrence of gallstones.
Gastritis and gastroesophageal reflux disease
Coffee beans can increase acid production in the stomach and thus the symptoms of gastritis and gastroesophageal reflux disease.
Cardiovascular diseases
Consumption of up to 6 cups a day has negatively affected existing cardiovascular diseases. Instead, study evaluations show that moderate consumption can positively affect the cardiovascular system.
Three cups of the hot drink also protect against stroke, as a Swedish study shows. Accordingly, little or no coffee consumption is associated with an increased risk of stroke in women.
Hypertension (high blood pressure)
Contrary to previous opinions, regular coffee consumption does not significantly affect blood pressure. In long-term observations, regular consumption did not act.
However, this discovery does not apply to all beverages or drugs containing caffeine. Pure caffeine (e.g., tablet form) can cause a moderate increase in blood pressure. Presumably, other coffee ingredients, such as chlorogenic acid, prevent an increase in blood pressure.
Hyperuricemia and gout
The consumption of coffee, regardless of whether in conventional or decaffeinated form, lowers the uric acid level and reduces gout risk. The exact mechanism is not yet known. Caffeine, which is assigned to the substance group of xanthines, may have an inhibitory effect on the enzyme xanthine oxidase. Thus, it has a similar impact on uric acid production as the uricostatic allopurinol.
However, the fact that decaffeinated coffee also had a slight uric acid-lowering effect, whereas tea did not, suggests that ingredients other than caffeine are responsible for this effect. Regular coffee consumption (contrary to the short-term insulin-increasing effect) is associated with a lower insulin level, which reduces the insulin-mediated inhibition of uric acid excretion.
Headache migraine
In the treatment of migraine attacks, drugs containing caffeine are often used, which have been shown to improve the effect. Genetic polymorphisms of the adenosine A2A receptors can influence the susceptibility to caffeine's side effects, such as insomnia or anxiety. Caffeine inhibits a specific amino acid transporter (EAAT3), which leads to an increase in glutamate levels, which cause the pain receptors to be sensitized.
However, it is also known that an irregular caffeine intake can cause headaches - not only for migraineurs. The so-called caffeine withdrawal headache develops within 24 hours if the regular information of 200 mg caffeine per day is interrupted for at least two weeks. As a rule, the headache resolves within an hour if at least 100 mg of caffeine is consumed, or it subsides spontaneously within seven days if there is no caffeine intake. The comparatively lower caffeine intake on non-working days has already been discussed as a trigger for "weekend migraines."
About 6-14% of migraine sufferers see caffeinated beverages as triggers for migraine attacks. There are different results on the relationship between migraines and caffeine consumption. Most studies have reported a higher prevalence of headaches, migraines, and chronic headaches due to increased caffeine consumption, but other studies did not confirm this connection. Therefore, a causal relationship between caffeine consumption and headache cannot be derived.
According to the epidemiological study results, caffeinated drugs and drinks can moderately increase the risk of developing a chronic headache. Other studies showed that after a gradual reduction in caffeine consumption, headaches no longer occurred, or the effectiveness of acute medication was improved
Cancers
Coffee consumption does not affect the risk of cancer. This has been proven for both cancer incidence and survival rate. Even some evidence shows that moderate consumption slightly reduces melanoma risk, non-melanotic skin tumors, breast and prostate cancer.
Liver disease
Regular coffee consumption seems to positively affect non-alcoholic fatty liver disease (decrease in fibrosis and inflammation). With cirrhosis, the mortality and liver carcinoma rates decreased. The effects occurred regardless of the caffeine content.
Kidney stones
Due to the sometimes high oxalic acid content, large amounts of coffee can promote kidney stones in predisposed people or under certain conditions. The effect is very different from person to person.
osteoporosis
Coffee in large quantities can increase calcium excretion. However, a negative influence is only to be expected - if at all - if the supply of calcium, vitamin, and vitamin D is insufficient at the same time and other risk factors are present. Corresponding studies also lack the distinction between coffee and caffeinated drinks and individual coffee drinks quality. The influence is classified as not very relevant.
Irritable bowel syndrome
Caffeinated drinks are among the foods that patients often describe as promoting symptoms. Presumably, an intestinal peristalsis-stimulating effect is responsible for this.
Urolithiasis (urinary stones)
The current guideline on urolithiasis recommends a limited intake of coffee. Like black tea, it contains significant amounts of oxalic acid.
However, the study situation on this is contradictory.
According to Medix Switzerland, it is unnecessary to avoid these drinks with
moderate consumption. These could even have a stone prophylactic effect