每天喝多少咖啡合适？How much coffee is suitable to drink every day?

参考消息网7月5日报道德国《法兰克福汇报》网站4月20日刊登题为《我能喝多少咖啡？》的文章，内容编译如下：

咖啡中含有咖啡因和大量生物活性物质。研究表明，定期饮用咖啡能降低罹患2型糖尿病和某些癌症的风险，例如子宫癌、肝癌、肠癌、口腔癌、喉癌、转移性前列腺癌和黑色素瘤。另外，它似乎还能预防帕金森症和阿尔茨海默病等疾病。据推测，咖啡中的抗氧化物能保护细胞，避免其受损，具有抗炎效果。此外，这些抗氧化物还能增强血脑屏障，对心血管系统发挥积极作用。研究进一步发现，适量饮用咖啡能降低冠心病、心衰以及中风的风险。

欧洲食品安全局认为，健康成年人的每日咖啡因安全摄入量为400毫克，大约相当于3到4杯普通咖啡或5到6杯意式浓缩咖啡。孕妇应减半，即每天最多200毫克。

咖啡本身热量很低，加上糖、糖浆、冰激凌、牛奶或奶油才会成为热量炸弹：一杯加牛奶的甜拿铁玛奇朵热量约为228千卡，而不加糖的黑咖啡热量仅有2千卡。

黑咖啡的提神作用大约能维持4小时。加入少许脂肪，例如少量牛奶，可能延长这种效果。饮用咖啡后，血压会在短期内升高，但会立即回落。定期饮用咖啡的人不会因此脱水，因为身体会适应咖啡因的利尿作用。咖啡还能轻微抑制食欲，提高基础代谢，从而有助于维持体重。

适量饮用咖啡显然也对骨骼有益。长期以来，人们认为咖啡会夺走钙质，因为咖啡因会增加钙的排出。然而，在适量饮用并保证其他途径摄入足够钙的情况下，咖啡的这一形象已经不再成立。

孕期应避免大量饮用咖啡，因为咖啡因可能增大流产、早产和低出生体重的风险。有趣的是，有些孕妇会自发地对咖啡产生厌恶。

无论是否含有咖啡因，咖啡都是可溶性纤维素的宝贵来源。有时，两杯咖啡所含的纤维素就和一小根香蕉相当。为了健康长寿，我们每日膳食的目标应该是至少摄入30克纤维素。因此，咖啡可以被列入有益植物性食物的清单。

除咖啡因以外，咖啡还含有咖啡醇和咖啡豆醇等二萜类化合物。这类物质可能具有抗癌特性，但如果摄入量过大，会轻微升高低密度脂蛋白胆固醇的水平。真正提高胆固醇水平的主要是饱和脂肪酸和反式脂肪；糖、精制面粉和果糖也会通过扰乱人体代谢，间接产生负面影响。餐后来一杯双份浓缩咖啡，对胆固醇水平的影响不大。

咖啡中有问题的物质是丙烯酰胺，它可能会致癌。丙烯酰胺是在烘焙过程中由糖和蛋白质反应生成的，在人体内会转化成能够破坏DNA的环氧丙酰胺。深烘焙咖啡的丙烯酰胺含量较低，因为如果烘焙时间延长，丙烯酰胺就会重新分解。此外，深烘焙咖啡通常更容易吸收，因为它们酸度较低。速溶咖啡和咖啡替代品(例如谷物咖啡)由于加工过程更为复杂，丙烯酰胺含量可能更高。（编译/王自强）

On July 5th, Reference News Network reported that the website of the German "Frankfurter Allgemeine Zeitung" published an article titled "How much coffee can I drink?" on April 20th. The content is compiled as follows:

Coffee contains caffeine and a large amount of bioactive substances. Studies have shown that regular coffee consumption can reduce the risk of type 2 diabetes and certain cancers, such as uterine cancer, liver cancer, intestinal cancer, oral cancer, laryngeal cancer, metastatic prostate cancer and melanoma. In addition, it seems to be able to prevent diseases such as Parkinson's and Alzheimer's disease. It is speculated that the antioxidants in coffee can protect cells from damage and have anti-inflammatory effects. In addition, these antioxidants can enhance the blood-brain barrier and have a positive effect on the cardiovascular system. Further research has found that moderate consumption of coffee can reduce the risk of coronary heart disease, heart failure, and stroke.

The European Food Safety Authority believes that the safe daily intake of caffeine for healthy adults is 400 milligrams, which is approximately equivalent to 3 to 4 cups of regular coffee or 5 to 6 cups of Italian espresso. Pregnant women should reduce their intake by half, with a maximum of 200 milligrams per day.

Coffee itself has very low calories, and adding sugar, syrup, ice cream, milk or cream makes it a calorie bomb: a cup of sweet latte macchiato with milk has about 228 calories, while unsweetened black coffee has only 2 calories.

The refreshing effect of black coffee can last for about 4 hours. Adding a small amount of fat, such as a small amount of milk, may prolong this effect. After drinking coffee, blood pressure will rise in the short term but immediately fall back. People who regularly drink coffee will not become dehydrated because their bodies will adapt to the diuretic effect of caffeine. Coffee can also slightly suppress appetite, improve basal metabolism, and help maintain weight.

Moderate consumption of coffee is clearly beneficial for bones as well. For a long time, people have believed that coffee takes away calcium because caffeine increases calcium excretion. However, with moderate consumption and sufficient intake of calcium through other means, the image of coffee is no longer valid.

During pregnancy, excessive consumption of coffee should be avoided as caffeine may increase the risk of miscarriage, premature birth, and low birth weight. Interestingly, some pregnant women may spontaneously develop a dislike for coffee.

Regardless of whether it contains caffeine or not, coffee is a valuable source of soluble cellulose. Sometimes, two cups of coffee contain as much fiber as a small banana. For health and longevity, our daily dietary goal should be to consume at least 30 grams of fiber. Therefore, coffee can be included in the list of beneficial plant-based foods.

In addition to caffeine, coffee also contains diterpenoid compounds such as caffeic acid and caffeic acid. These substances may have anti-cancer properties, but if consumed in large amounts, they can slightly increase levels of low-density lipoprotein cholesterol. The main factors that truly increase cholesterol levels are saturated fatty acids and trans fats; Sugar, refined flour, and fructose can also indirectly have negative effects by disrupting human metabolism. A double cup of espresso after a meal has little effect on cholesterol levels.

The problematic substance in coffee is acrylamide, which may cause cancer. Acrylamide is generated by the reaction of sugar and protein during the baking process, and is converted into glycinamide in the human body, which can damage DNA. Deep roasted coffee has a lower acrylamide content because if the roasting time is prolonged, acrylamide will decompose again. In addition, deep roasted coffee is usually easier to absorb because they have lower acidity. Instant coffee and coffee substitutes (such as grain coffee) may have higher levels of acrylamide due to their more complex processing. (Compiled by Wang Ziqiang)