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.