Core tip: Among all beverages, coffee has probably been the most researched. One day a scientist says coffee can prevent cancer, the next day another says it can harm the stomach, leaving people truly "not knowing who to listen to". If we look at all the various studies together, is drinking coffee ultimately good or bad for you?
Coffee is a completely foreign beverage. As international exchanges gradually increase, more and more Chinese people are developing a taste for it. Among all beverages, coffee has probably been the most researched. One day a scientist says coffee can prevent cancer, the next day another says it can harm the stomach, leaving people truly "not knowing who to listen to". If we look at all the various studies together, is drinking coffee ultimately good or bad for you?
Coffee is an extract from coffee beans, containing no fewer than several hundred components. Among them, caffeine is undoubtedly the most important. Although there is "decaffeinated" coffee, for most coffee lovers, it doesn't count as "real" coffee. Caffeine stimulates the nervous system, so coffee's primary effect is to "refresh". Caffeine combined with glucose can mutually enhance this refreshing effect. Many sports drinks also add caffeine as a legal "stimulant".
Whether caffeine has other "health benefits" has also attracted a great deal of scientific attention. There are many such studies, and overall, some show "it might be effective". For example, some elderly people experience dizziness after meals due to low blood pressure; drinking a caffeinated beverage might alleviate this symptom. By "caffeinated beverage," we mean not just coffee, but also tea or cocoa. Parkinson's disease is a common ailment in the elderly, and surveys show that caffeine is quite effective in reducing the risk of its occurrence. For men, the maximum effect is achieved with three to four cups a day, while one or two cups also have a significant effect. For women, the effect is less related to the amount consumed, with the maximum effect achieved with one to three cups a day. Interestingly, this effect does not exist in smokers. Furthermore, caffeine also helps in reducing the risk of gallstones; an effect can be seen with 400 mg of caffeine per day (roughly three to four cups of coffee). Interestingly, the relationship between caffeine intake and the risk of type 2 diabetes is more closely related to ethnicity than to the amount consumed. In European and American populations, drinking six cups of coffee a day can reduce the risk for men by over 50% and for women by around 30%. In the Japanese population, drinking three cups a day can reduce the risk by 42%.
Besides caffeine, coffee also contains many other "active components," such as antioxidants. The content of antioxidants is particularly high in roasted coffee beans. Antioxidants are beneficial for cardiovascular health, but coffee also contains "harmful substances," such as diterpenes, which increase the risk of cardiovascular disease. In this "tug-of-war," it depends on which side dominates. Fortunately, diterpenes can be filtered out by a paper coffee filter, so unfiltered coffee or coffee filtered with a metal mesh is not recommended. A similar situation exists with the "anti-cancer" effect; some studies suggest that drinking three cups of coffee a day may reduce the risk of colorectal cancer. However, while roasting increases the content of antioxidants, it also produces acrylamide, and high doses of acrylamide have shown carcinogenicity in animal experiments.
Coffee's "negative effects" are not limited to these. If you drink too much coffee per day (for example, more than six cups), it can lead to addiction, a decreased sensitivity to caffeine, which in turn leads to consuming even more. Drinking too much can cause symptoms like insomnia, nervousness, stomach discomfort, nausea, vomiting, increased heart rate and breathing, headaches, and tinnitus. For people with heart conditions, five cups a day is considered an "unsafe" amount.
Many people are concerned about whether pregnant and breastfeeding women can drink coffee. Based on current scientific evidence, it is generally considered acceptable to drink no more than two cups a day (about 200 mg of caffeine). If pregnant women exceed this amount, it increases the risk of miscarriage, premature birth, or low birth weight. For breastfeeding mothers, exceeding this amount might irritate the baby's digestive system and affect the baby's sleep.
Generally speaking, children are more sensitive to caffeine than adults. Considering that avoiding side effects is more important for children, it is recommended that children最好不要喝咖啡.
Although some survey data shows that coffee can reduce the risk of type 2 diabetes, research on the effects of caffeine on blood sugar shows both increases and decreases. Therefore, for diabetics, if they choose to drink coffee, they must pay close attention to their blood sugar levels and make adjustments in a timely manner.
In addition, coffee can also increase calcium loss. If you have symptoms of osteoporosis, your daily caffeine intake should not exceed 300 mg (equivalent to two to three cups of coffee). Elderly women are very prone to osteoporosis and therefore need to be even more careful.
When it comes to drinking coffee, more attention should be paid to its interaction with medications. The one that requires the most caution is ephedrine, which has a stimulating effect on the nervous system. When combined with coffee, its effect is greatly enhanced, leading to symptoms of "overdose." Ephedrine is commonly found in cold medicines, such as Contac and Baijiahei.
In addition, the metabolism of many drugs can interact with the metabolism of caffeine. These interactions can either increase the effects of caffeine (including its side effects), increase the effects of the drug, or decrease the effects of the drug. Drug dosages are designed based on their normal effects; either enhancement or reduction will affect the treatment. Too many drugs can interact with caffeine for an ordinary person to remember, so the simplest approach is: do not drink coffee while taking any medication.
As a complex natural extract with different components having different effects, it is not surprising that different experiments yield different results. As a beverage, coffee may have dazzling "health benefits," but it may also have worrying "side effects." Most of these research findings are from epidemiological studies, and the conclusions are by no means final. Synthesizing these pro and con studies, the currently more widely accepted recommendation is: for healthy adults, drinking two to three cups of coffee a day, the "benefits" outweigh the "risks"; for pregnant and breastfeeding women, no more than two cups is also acceptable. For other populations, it is necessary to weigh the specific circumstances.