There are many studies mentioning the health benefits of drinking coffee, such as refreshing the mind, relieving fatigue, preventing type 2 diabetes, and preventing certain cancers. A recent study by a team of researchers from Soochow University shows that coffee consumption can even offset the harm caused by sedentary behavior – the risk of death for people who sit for ≥6 hours a day without coffee is 1.58 times higher than that of people who sit for <6 hours a day and drink coffee; in the group of people who don’t drink coffee, the longer the time of sedentary behavior, the higher the risk of all-cause mortality.
Even so, coffee is not suitable for everyone, there are 9 categories of people can not blindly drink coffee, must pay special attention.
People who do not sleep well
Coffee contains high levels of caffeine, which has a certain refreshing effect. Caffeine and the body’s energy supply material adenosine triphosphate (ATP) metabolite adenosine structure is similar to the competition can be combined to cause fatigue and sleep signal receptors, play to promote arousal, improve fatigue biological activity.
Because of this, many office workers rely on coffee to get energized and work hard.
Studies have shown that caffeine is rapidly absorbed in the human body, generally reaching its peak in 15 minutes to 2 hours after drinking, spreading throughout the body and crossing the blood-brain barrier. The half-life of caffeine in adults is generally 2.5 to 4.5 hours. Therefore, under normal circumstances in the plan to go to bed before 5 hours to drink coffee, the normal sleep will not have a great impact, such as 22:00 bedtime, then drink coffee before 5:00 p.m..
However, the tolerance level of caffeine varies among different groups of people. For people who have poor sleep, insomnia or sleep disorders, they should try to drink less or no coffee.
People with arrhythmia
Although it is normal for the heart to beat faster after drinking coffee, it still needs to be taken seriously, especially for people who have arrhythmia themselves.
Arrhythmias are irregular, fast or slow heartbeats caused by abnormal electrical conduction in the heart. More than 80% of U.S. doctors recommend that patients with palpitations or arrhythmias quit or reduce their caffeine intake.
There is also some research that suggests that for most people, even patients with arrhythmias or people at high risk for arrhythmias, a caffeine intake of less than 400 mg per day appears to be safe, and may even be protective against arrhythmias, although there is no clearly defined threshold for caffeine harm; however, for people with malignant arrhythmias and people at high risk for caffeine-sensitized arrhythmias, it is still important to avoid caffeine as much as possible.
400 mg of caffeine is equivalent to no more than 4 cups of plain coffee (150 ml/cup). If the coffee is bought, you can calculate the number of cups by comparing the amount of caffeine per cup on the label of the package; if it is a small packet of 1.8~2 grams of instant coffee, it is generally limited to a maximum of 5 sachets per day.
People with stomach problems
Coffee will stimulate the gastrointestinal tract and increase the secretion of stomach acid.
This will not affect the health of people with normal stomach function. However, for people who have stomach problems themselves, such as those suffering from gastric ulcers, excessive acid secretion, or gastroesophageal reflux disease, regular or excessive coffee consumption may lead to nausea, vomiting, acid reflux, heartburn, and other symptoms.
People with irritable bowel syndrome
Irritable bowel syndrome is a very common functional bowel disease, patients may have frequent diarrhea, constipation.
Caffeine in the digestive system can stimulate the secretion of gastric acid and cholecystokinin, which can promote the movement of the colon and cause diarrhea and other symptoms. In general, patients with irritable bowel syndrome are more sensitive to caffeine and may experience increased gastrointestinal discomfort and diarrhea after consumption. Reducing caffeine intake can reduce the occurrence of symptoms associated with irritable bowel syndrome.
People with severe anemia
The polyphenols and tannins in coffee have no effect on the absorption and utilization of heme iron. In general, we mainly rely on heme iron in our meals to replenish iron and blood, such as lean meat, pork liver, duck blood, razor clams, etc., and the effect of coffee on the iron in a meal is only about 6%. Therefore, healthy people do not need to worry about drinking a few cups of coffee will lead to anemia.
However, the polyphenols, caffeine, phytic acid and other botanicals in coffee will combine with iron, snatch the position of iron ions and reduce the rate of iron absorption, thus affecting the absorption of non-heme iron. Therefore, for people who are already severely anemic, it is advisable to reduce coffee intake appropriately to avoid affecting the body’s iron storage level.
People with osteoporosis
Caffeine and ellagic acid in coffee do affect calcium absorption, and caffeine diuretics increase calcium loss, but this is not a significant effect on healthy people. Some studies have mentioned that the negative effect of caffeine on calcium absorption is so small that it only takes 1~2 tablespoons of milk to completely counteract it.
Based on a large amount of population data, food safety regulators such as the European Food Safety Authority, the U.S. Food and Drug Administration, Health Canada, and the Food Standards Agency of Australia and New Zealand have concluded that a daily caffeine intake of 400 mg or less in healthy adults will not adversely affect cardiovascular function, behavior, reproduction and development, bone health, and there is no risk of acute toxicity. Therefore, healthy people do not need to worry about osteoporosis caused by drinking coffee.
Glaucoma patients
Studies have shown that the caffeine contained in coffee can cause an abnormal increase in intraocular pressure in glaucoma patients, which is a risk factor for the development of glaucoma. Elevated intraocular pressure can cause damage to the optic nerve and visual function, which can lead to serious blindness.
Therefore, glaucoma patients should avoid drinking coffee, which is high in caffeine, in their daily life to avoid further damage to the eyes caused by elevated and fluctuating intraocular pressure.
Children and adolescents
The internationally recommended safe intake of caffeine for children and adolescents is not more than 2.5-3 mg per kilogram of body weight. That means, for example, for a child or adolescent weighing 40 kilograms, the amount of caffeine intake is 100-120 mg, which is about 1 cup of coffee. Of course, it is better not to drink it.
This is because children who are growing and developing have a weaker ability to metabolize caffeine than adults, which can affect not only sleep but also physical development.
Pregnant and lactating women
The Scientific Consensus Related to Coffee and Health states that coffee is not recommended for pregnant women and, if consumed, should not exceed 2 cups per day. Although Health Canada, the American College of Obstetricians and Gynecologists, the American Pregnancy and Childbirth Association and other organizations believe that coffee can be consumed in small amounts during pregnancy (no more than 150-300mg of caffeine per day, or about 2 cups), pregnant women should not be encouraged to drink coffee.
Therefore, for women who have never had the habit of drinking coffee, it is recommended not to drink coffee during pregnancy and breastfeeding; while for women who have always had the habit of drinking coffee, it is best to limit the consumption of coffee.
Summarize
Although drinking coffee is good for health, it should be limited. The Scientific Consensus on Coffee and Health recommends that caffeine intake for the average adult should be limited to 400mg per day.
Different people have different levels of tolerance to caffeine, and it is recommended that the nine groups of people mentioned in the article, as well as those who are sensitive to caffeine, should limit or avoid caffeine intake according to their own circumstances.