Red wine - what's behind its healthy reputation?

What is in red grapes that gives red wine such a good press?

In recent years, red wine has received some pretty good press. When we think of a healthy form of alcohol, red wine tends to be the top choice.

But why - and does it deserve all the attention?

Scientists agree that there is something in red wine that, when drunk in moderation, can help to protect the heart, reduce 'bad' cholesterol and prevent blood clots.

But there is little agreement of what is causing those beneficial effects.

Recently, Uruguayan chemists went to such great lengths to discover the secret of their healthy home-grown red wine that they sequenced the genome of the Tannat grape from which it is made.

That was prompted by the discovery that those wines contained high levels of procyanidins - a class of flavanols found in plants, fruit and cocoa beans.

Roger Corder, professor of experimental therapeutics at Queen Mary University of London and author of The Red Wine Diet, made the discovery and confirms that the Tannat wines contain three to four times more procyanidins than Cabernet Sauvignon.

He says they - alongside the high concentration of tannins, which combat the ageing of cells - are likely to be behind its health-giving properties.

Other scientists are excited about a compound found in the skin of red grapes called resveratrol.

For many years, it has been hailed as a kind of wonder drug - an anti-ageing compound, which could extend life, combat obesity and cure cancer.

But, so far, studies on resveratrol have taken place in the lab - as yet there is no evidence that it can be effective in humans.

Cancer connection

Dr Emma Smith, science communications officer at Cancer Research UK, says it is a mistake to drink red wine and believe it is doing good.

Not all red wines are made the same way

"Red wine only contains very small amounts of resveratrol and people shouldn't drink wine in an attempt to get any health benefits.

"It's important to remember that, even in moderate amounts, alcohol increases the risk of several cancers and has been estimated to cause around 12,500 cases of cancer a year in the UK."

Researchers at the University of Leicester are, however, looking at whether resveratrol, on its own and not in red wine, could one day be developed into a cancer-preventing drug.

Experimenting on mice in the lab, they have found that a daily amount of resveratrol equivalent to two glasses of wine can halve the rate of bowel tumours.

They now want to take their findings further and find out how the compound might work in humans by carrying out clinical trials.

Prof Karen Brown, from the department of cancer studies and molecular medicine at Leicester, says her research must not be misconstrued.

"We're not saying red wine can prevent cancer - we are looking at the pure compound.

"Alcohol is not good for cancer - but it just so happens that red wine contains resveratrol."

Good pips

Even in red wine, Prof Roger Corder says there is little evidence that resveratrol is an important ingredient.

"It's a myth that resveratrol has anything to do with the health benefits of red wine.

"Most red wines contain only negligible amounts of resveratrol and those that do contain some have too little to have any effects."

Instead he says it's the pips, and not the grape skin, which are key.

When the grapes are fermented for several weeks or more, that is when flavanols can be released from the pips and these evolve into more complex molecules.

But the bad news is that doesn't always happen with all wines, he says.

"Most modern style wines don't take that approach to wine-making."

What people should focus on, he says, is drinking wine in a healthy way.

"It's very hard to say wine is a healthy drink when people consume too much alcohol, at the wrong time of day and without food."

The best way to drink wine is in moderation with food, Prof Corder says.

Taken in this way, wine is more likely to have a beneficial effect on our health - not an adverse one.