What's in that glass?

Are unsavoury - and unlabelled - additives in beer and wine to blame for that Christmas hangover?

'Tis the season to be merry - but a night of festive spirit may leave partygoers suffering unduly because of the unexpected additives in alcoholic beverages.

Tis the season to get in the, er, spirit

Because Europe's labelling laws do not cover alcohol, producers do not have to list the ingredients used.

Yet these could include dried bull's blood, sulphur or fish bladders.

The directive forbids listing the ingredients, a regulation Co-op flouts by printing a complete list of ingredients on some varieties of its own-brand wine.

Some New World wines, with labels spelling out what is inside the bottle, are altered when imported into the UK.

Chris Huhne, a Liberal Democrat MEP, has called on the government to push for a comprehensive labelling system to protect revellers from what he called "dodgy booze".

Colourless drinks are less likely to trigger headaches

There is no reason why alcohol should not be subject to the same rules as other food and drinks, Mr Huhne said on Friday.

"And there is nothing to stop Britain implementing such a scheme on public health grounds," he added.

The Consumers Association supports the push for an EU-wide alcohol labelling system.

Yet member states with a long tradition of winemaking have been reluctant to push the issue, a spokeswoman says.

"France has been very protective of its wine industry."

What it doesn't say on the bottle

So what might be in that festive tipple?

In 1997, in the wake of the BSE scare, the French banned the centuries-old practice of using dried bull's blood in red wine.

"The grape and nothing but the grape - NOT"

Yet 18 months ago, the authorities seized 100,000 suspect bottles after investigating 14 vineyards in the Cotes du Rhone area. The region exports millions of bottles of table wine to the UK each year.

The blood is used as a clarifying agent, which captures particles that occur naturally during the winemaking process. Alternatives include fish bladders, egg white, gelatine and clay.

Then there is the preservative sulphur dioxide, which can cause headaches and asthmatic reactions.

Other drinkers find they react badly to congeners, which add flavour and colour and are found in cognac, brandy, whisky and red wine.

Purity laws

Yet beer drinkers need not look so smug.

Many brewers use chemical additives to improve the ''head'', increase shelf-life or alter the colour or flavour.

"No hangover? You cannot be serious"

However, microbrewers the world over look to Germany's purity laws of 1516, or Reinheitsgebot, which stipulate that beer should be made only of water, malt, hops and yeast.

Thomas Lange, of the beer and brewing website Breworld, says the purity laws were overridden by the EU about a decade ago.

Until then, Germany's borders were closed to "adulterated" brews such as the fruit beers of Belgium.

"But we continue to adhere to the Reinheitsgebot. It is now still illegal to brew beers with preservatives for German markets - only for export into very hot countries."

Instead of chemical additives, some German brewers use heat pasteurisation to "nuke" any lurking bacteria and extend the shelf-life of their product, Mr Lange says.

So what of the claims that drinking such a brew means no hangover?

"I subscribe to the theory that if you drink better beer, you don't suffer as badly. Maybe that's because if you drink a quality brew, you don't often drink eight pints."