Confused over coffee

I had always been an enthusiastic tea drinker. So when I was forced to give up tea for medical reasons, it was only natural that coffee became my hot brew. “Coffee?” asked my tea-drinking friend, P, who needed some convincing that I wasn’t doing it for the snob value of coffee over tea. “Thought you knew coffee causes bladder cancer,” he pronounced sagely.

Well, I know P to be a conscientious eater and a bit of a know-all when it comes to these sorts of things. To give you an example, once when I was mulling over Atkins diet, this is what he told me, “Eating six eggs a week is fine, but if you go for the seventh one, your heart attack risks go up by 23 per cent.” Oh no, he wasn’t making it up. He was quoting from a Harvard study! Check the Net if you don’t believe.

Naturally, I decided to do some research on coffee and came to the conclusion that caffeine was indeed thought to induce colon bladder cancer. But the latest studies were more heartening: a coffee drinker enjoyed some protection against liver damage, Parkinson’s, diabetes, Alzheimer's, gallstones, depression and maybe even some forms of cancer.

In fact a Time magazine article titled Measuring IQ Points by the Cupful said coffee heightened one’s mental performance.
I sent the link to P, who commented, “hogwash!
But just when I was thinking I was getting brainier and smarter thanks to two cups of coffee per day, came the new research finding last week that it was indeed all myth—coffee doesn’t even make you alert.
"Although caffeine consumers feel alerted by caffeine, the effect is actually only bringing you back from caffeine withdrawal-induced, low-level alertness,” said a widely reported study originally published in the reputed Neuropsychopharmacology journal.
More galling was the fact that P laid his hands on the report before me and promptly sent an sms…

I’ve decided to stop trying to keep abreast of these so-called research and studies about food, nutrition and health are making us more confused. Hardly a day goes by without us reading about some breakthrough study which is contradictory to the previous ones. Consider these samples:
* Vitamin supplements are extremely beneficial/
It’s a waste to consume vitamin supplements.
* Eggs are bad coz they have cholesterol/Eggs are ok coz they have good or neutral cholesterol.
* Milk is excellent for health and helps fight osteoporosis / The combination of calcium and protein might set off osteoporosis.
* Moderate drinking, esp wine, is good for heart/Even low to moderate drinking is bad for heart.

All these studies have been conducted by reputed institutions and published in prominent health journals. Is it just me, or you guys are confused too? Is some lobbyism at work here? Or are the researchers looking at things through a narrow prism?
The best guide in these matters, I think, is good ol’ common sense, wot say?