Every other week, new studies appear that either demonize or eulogize the mighty roasted bean. Are there grounds for concern under the aromatic froth?

Pros

Diabetes:A study of 14,000 people in Finland (the world's greatest per-capita consumer of coffee) found that women who drank three to four cups a day cut their risk of developing diabetes by 29 percent. For men, it was 27 percent. Researchers aren't sure why, but suspect that the antioxidants in coffee help deliver insulin to the body's tissues.

Cancer:In Japan, a study of 90,000 people revealed those who drank coffee every day for ten years were half as likely to get liver cancer. Meanwhile, German scientists have identified an active compound in coffee called methylpyridinium that boosts enzymes thought to prevent colon cancer.

Parkinson's Disease:Researchers in Hawaii monitored the health of more than 8,000 Japanese-American men for 30 years and discovered that those who drank a cup of coffee a day had less than half the incidence of Parkinson's disease. A possible clue as to why: caffeine promotes the release of dopamine, a substance involved with movement and usually depleted in Parkinson's sufferers.

Gallstones:A US study of 46,000 men who drank two to three cups of coffee a day over a ten-year period revealed they had a 40 percent lower risk of developing gallstones. Researchers believe it is because caffeine stimulates the gall bladder, flushing out substances that could turn into gallstones.
Cons

Heart Attack and Stroke:There's hot debate on whether drinking coffee is a cardiac risk. A Greek study of more than 3,000 people found coffee drinkers had higher levels of inflammatory substances (which have been associated with increased rates of stroke and heart attack) in their blood than non-drinkers. But Harvard researchers looking at the health of coffee drinkers over 20 years could not pinpoint any extra coronary problems. Nevertheless, a study of 2028 Costa Ricans found those with a gene variant that processes caffeine four times slower than average, and who also drank two to three cups of coffee a day, upped their heart-attack risk by 36 percent. As this group metabolises caffeine slower, it remains in the body for longer—possibly pushing up blood pressure.

Rheumatoid Arthritis:A Finnish study of 19,000 people revealed those who drank four or more cups of coffee a day were twice as likely to develop rheumatoid arthritis. Researchers believe some as-yet-unidentified ingredient (particularly in unfiltered coffee) could trigger the disease.

Osteoporosis:A Californian study of 980 post-menopausal women found that those who drank two cups of coffee a day suffered a greater loss in bone density than those who didn't. How come? Because caffeine acts as a diuretic, increasing the amount of calcium excreted in urine.

The Verdict

For most of us, the humble cup of coffee is simply a harmless and enjoyable way to kick-start the day or give us an excuse for some time out. No more, no less. However, it is important to remember that different people exhibit different tolerance levels to caffeine—it is, after all, a drug.

So, while a mid-morning cappuccino will give one person a pleasant buzz, it could make another person edgy and irritable. To play it safe, it's best to err on the side of caution. Whatever your choice—espresso or latte—keep a watch on your consumption for the sake of both your short-term and long-term health.

每周都会出来些新的研究反对这种万能烤豆子，下一周又会有研究出来赞美它。这些隐藏在香浓的泡沫之下的担心，有没有确凿的证据呢？

支持：

糖尿病：芬兰（世界人均消费咖啡最高的国家）一项有14000人参加的研究发现，每天喝三到四杯咖啡，女性罹患糖尿病的可能要减少29%，对与男性来说，要减少27%。研究人员不确定原因，不过他们推测咖啡中的抗氧化物质可以帮助胰岛素传到到身体的各部分组织中。

癌症：在日本，一项有90000人参加的研究发现，那些十年来每天喝一杯咖啡的人，罹患肝癌的可能性要降低一半。德国的科学家也确认了咖啡中一种名叫methylpyridinium的活跃成分可以提升酶，这被认为可以预防结肠癌。

帕金森症：夏威夷的研究者们通过三十多年对于8000多名日裔美籍男性的健康监测发现，那些每天喝一杯咖啡的人罹患帕金森症的情况不到那些不每天喝咖啡的人的一半。一种可能的原因是：咖啡因促进了多巴胺的分泌，这种物质和运动有关，在帕金森患者中它的分泌通常被消耗掉了。

胆结石：美国一项研究，研究了46000名每天喝2-3杯咖啡超过10年的男性，他们发现这些人出现胆结石的危险要低40%。研究人员们相信，这是因为咖啡因刺激了胆管，排出了那些可能会转化成结石的物质。

反对：

突发心脏病和中风：关于喝咖啡是否对心血管有危害的争论十分激烈。一项超过3000人参加的希腊研究发现，喝咖啡的人血液中的炎症物质（与中风和突发心脏病有关）比不喝咖啡的人要高。但是哈弗大学的研究者通过20多年跟踪喝咖啡的人的健康情况，他们没有发现更高的冠心病发病率。另外，一项关于2028位哥斯达黎加人的研究发现，那些基因决定消化咖啡因的速度比常人慢4倍的人，如果他们每天喝2-3杯咖啡，他们突发心脏病的危险要高36%。对于这些代谢咖啡因慢的人，咖啡因在体内时间更长，这可能会提高血压。

类风湿关节炎：一项关于19000人的芬兰研究发现，那些每天喝超过4杯咖啡的人，罹患类风湿关节炎的可能要高出一倍。研究人员相信，一些还没有被确认的物质（尤其是未过滤的咖啡中），可能会引发这种疾病。

骨质疏松症：加利福尼亚州的研究者，研究了980名更年期之后的女性，他们发现那些每天喝两杯咖啡的女性骨密度的流失要更高。为什么？因为咖啡因有利尿的作用，这使得通过尿排出的钙质更多。

最终决议

对于我们中的大多数人来说，一杯暖和的咖啡，仅仅是一种无害而享受的方式，来开启一天的工作或者找借口休息一下。不多也不少。不过，要谨记这一点，不同的人对于咖啡因的耐受性并不相同——毕竟，咖啡因是一种药。

所以，上午的一杯卡布奇诺可能给你带来的是愉快的好心情，但对有些人来说，可能就是烦躁和坏脾气。安全起见，最好小心行事。不论你如何选择——浓缩咖啡还是拿铁——注意你喝的量，不论是对你短期还是长期的健康，都有好处。