Ageing lotharios and sexually-frustrated wives and girlfriends are breathing a sigh of relief today, with the news that a daily German sausage can increase male potency by up to 63 percent.

German scientists at the Bad Kissingen Institute for Sexual Behaviour say that the effect on the male libido is virtually the same as taking Viagra.

In clinical tests carried out over five years, the researchers found that eating a daily Bratwurst increased potency and sex drive in males over 50 by over 63 percent in most cases.

The secret, so the scientists say, lies in the distinct mixture of herbs and spices in the German national dish and has an extraordinary effect on male sexual behaviour if eaten over a long period. Bratwurst is a traditional German pork and veal sausage, seasoned with a secret mix of herbs and spices including ginger, marjoram, caraway and coriander.

Putting a tiger back in their tank

Over 1,000 males over 50 from all over the country underwent the field trials, which saw them chomping on a different type of German sausage every week.

One of the volunteers, Reinhard Schmidt, (52) spent five years being force-fed the German national dish by his wife in a bid to revive their flagging sex life.

"At first, I was unsure, as I'm not really a big fan of sausages, but my wife convinced me that it might put a tiger back in my tank! I didn't like the idea of medicines and this seemed like a natural alternative," Schmidt said, admitting that life between the sheets was now the "best it had ever been" in their 30- year marriage.

Another, Thomas Schmatzer (60), was also over the moon. "My girlfriend is a bit younger than me and I was getting slightly concerned about, well, you know what," he admitted shyly. "But this Bratwurst trick has got me feeling like a spring chicken again." Schmatzer said his girlfriend stocked up on sausages three times a week to make sure they would now never run out of the natural love drug.

But the researchers cautioned that the effects did vary according to the male's natural sex drive. "We're not saying this a miracle cure, but it definitely does, er, boost things. It certainly seems like a good old sausage is the answer that many men of a certain age have been looking for," Matthius Raubtier, the scientist leading the trials, said.

The head of the German Sausage Makers Association (VWH), Gunther Riecken, said: "This is great news for sausage makers all over Germany."