According to statistics from the International Coffee Organization, 400 billion cups of coffee are consumed worldwide each year, and 14,000 cups are drunk every second. As more and more coffee drinks and coffee shops appear in daily life, Chinese people's enthusiasm for coffee seems to be slowly rising, but many people still feel that "caffeine" is a threat, and they always think that drinks that suddenly make people energetic must be bad for the body. Is coffee harmful to health? How to drink it to get more health benefits? Recently, a new study published in the Journal of the International Society of Sports Nutrition gave answers to the questions that everyone is concerned about.
Dehydration refers to a symptom of metabolic disorders caused by the human body consuming a lot of water due to pathological changes, and cannot be replenished immediately. In severe cases, it can cause collapse and even life-threatening. The judgment of dehydration is not only based on urine volume, but also needs to consider multiple factors such as the body's water intake, sweating, and ambient temperature. Many people think that drinking coffee is a diuretic and will cause dehydration. The caffeine in coffee does have a certain diuretic effect, which means that drinking coffee may increase urine volume and cause the body to excrete more water. However, whether this diuretic effect is sufficient to cause dehydration needs to be considered in combination with specific circumstances. Studies have shown that only excessive coffee intake can lead to a sharp increase in urine volume, and drinking coffee in moderation will not be a problem.
Compared with simply consuming a moderate amount of coffee, factors such as sweating and genetics have a greater impact on whether dehydration occurs during exercise. Studies have found that compared with drinking a placebo, consuming a moderate amount of coffee did not significantly differ in terms of fluid retention, urine volume, and percentage of dehydration. Therefore, dehydration during exercise has nothing to do with drinking coffee.
The effect of coffee on weight loss is affected by many variables: one is the dietary intake standard, and the other is whether the subject has drunk coffee before participating in the study. In addition, the dose of coffee, the weight of the participant itself, etc. may also affect the final conclusion. Therefore, current evidence does not support the use of coffee to assist weight loss.
Although moderate coffee intake can temporarily relieve some depressive symptoms and even improve mood, excessive drinking can increase anxiety, disrupt sleep, and have adverse effects on mental health. Therefore, people with depression should control their coffee intake and seek professional guidance when necessary.
Excessive intake of caffeine can be fatal. The median lethal dose (LD50) of caffeine depends on body weight and personal sensitivity, usually 150 to 200 mg per kilogram of body weight. This means that an average adult needs to consume a large amount of coffee (such as 140 to 180 cups) in a limited time to reach this lethal dose, but healthy people will not reach a lethal dose through caffeine intake through coffee, which is almost impossible in daily life, so there is no need to worry.
Drinking coffee has many benefits for cardiovascular health, such as improving endothelial function and reducing the risk of atherosclerosis; it is negatively correlated with the incidence of stroke and heart failure; it helps reduce the risk of type 2 diabetes (a major risk factor for cardiovascular disease). Therefore, although there is an association between excessive caffeine intake and adverse cardiovascular outcomes, there is no evidence that moderate coffee intake has an adverse effect on heart health.
The evidence is not clear. Caffeine inhibits vitamin D function and changes the expression of vitamin D receptors. However, some studies have shown that coffee intake is positively correlated with bone mass, which may be related to the high antioxidant and anti-inflammatory properties of coffee. Therefore, more clinical studies are needed to prove the relationship between the two.
Epidemiological studies have shown that caffeine intake during pregnancy is associated with adverse pregnancy outcomes, but the underlying mechanism is still unclear. The American College of Obstetrics and Gynecology, the American Pregnancy and Childbirth Association and other institutions have claimed that consuming less than 300 mg of caffeine (about 3 cups of coffee) per day during pregnancy is unlikely to harm pregnancy health. Ruan Guangfeng, deputy director of the Kexin Food and Health Information Exchange Center, also said in an interview with the "Global Times Health Client" reporter that for pregnant women, less than 300 mg is a safe dose.
Many people shared on social media that you should not drink coffee immediately after getting up in the morning. It is best to drink it one or two hours after waking up to avoid its effect in the afternoon. But this statement is not supported by scientific evidence and should not be followed.
Ruan Guangfeng said that the US Food and Drug Administration, the European Food Safety Authority, the Canadian Ministry of Health and other authoritative organizations all recommend that healthy adults should not consume more than 210-400 mg of caffeine per day (equivalent to 3-5 cups of coffee). Coffee lovers should pay attention to controlling the amount of drinking, and it is best to choose pure coffee without additives. The popular instant three-in-one coffee or other fancy coffees on the market may contain a lot of sugar and non-dairy creamer, which is not good for health. If you think black coffee is too bitter, you can add milk or milk powder in moderation.
Ruan Guangfeng especially reminded that the following eight groups of people should pay attention to controlling their coffee intake: those with sleep disorders, those with panic anxiety, those with arrhythmia, patients with iron deficiency anemia, patients with gastric acid reflux, patients with irritable bowel syndrome, and patients with hypertension.
In addition, because individual tolerance to caffeine varies greatly, if symptoms such as insomnia, anxiety, trembling, stomach discomfort, increased heart rate, headache, nausea or irritability occur, it may be caused by excessive caffeine intake, and timely adjustments should be made. People who are used to drinking coffee should drink less other caffeinated beverages, such as cola, tea, milk tea, etc., to avoid excessive caffeine intake and affect health.
