Mountain springs, pure water, the finest hops and barley. What more could there be to beer?

More than 100 things, actually.

Additives in beer is not a new idea. In the 15th century brew masters threw a live chicken into the beer kettle and called the result cock's ale. Today, no chickens, but the Candian government still allows as many as 108 ingredients in beer.

They make tiny bubbles tinier, foamy head foamier, liquid more transparent. But which of those 108 actually end up in your brew? You'll never know by looking at the label, because when it comes to listing what's inside, Health Canada makes an exception for beer.

Sharon McDiarmid of Health Canada

"There are all kinds of ingredients that could go in there, certainly," says Sharon McDiarmid of Health Canada. "That doesn't mean everybody uses them. They're optional. These are ingredients that are approved for use by Health Canada."

But what's in beer doesn't end with the original recipe, she added.

"The ingredients you start with change so much through the distillation or fermentation process. So what you end up with is not what you start with. So it's somewhat misleading to say these ingredients are present when they have undergone this transformation."

When asked if that was another way of saying we don't know what's in beer, McDiarmid said "No, not at all."

Rob McCaig is Molson's brewmaster. He says listing all the ingredients in a bottle of beer would be virtually impossible.

Rob McCaig

"A lot of them are not identifiable because they cross over with other ones," he says.

"We put malts, hops together with yeast. It's transformed, up to a thousand different flavour compounds. So ideally if you get a list of ingredients you should have to go through and list all of those. We won't have room on the label or the case to label individual bottles."

Liam McKenna is a brewmaster and beer making expert -- part chemist and part chef-- who left Toronto to set up his own brewery in a city famous for its pubs, Dublin.

Liam McKenna

"They're not doing it to try and poison the consumer," he says, adding, "There's really never been a case of ... of a beer killing a person, with very, very few exceptions."

One of those exceptions happened in 1964, when a Quebec brewery, Dow, put cobalt sulfate into its beer. 16 men die and millions of gallons were flushed down the sewer.

"They died of cobalt sulfate poisoning," said McKenna "Now, cobalt at the time, heavy metal, was used as a head retention agent."

Today, Canadian beer is recognized as one of the safest in the world. But for critics at home and abroad, that's not good enough.

"Whether you view beer as a ... a drug or as a food product or merely as a recreational libation, there is no other product, whether it be Coca-Cola or ice cream, bread, pharmaceuticals, they have to list the ingredients on them to protect the consumer, to allow the consumer to make an informed decision about what they're applying to their body or putting into their body," McKenna said.

Liam McKenna has made beer labels a national issue here, lobbying parliament to make Ireland the first country in Europe to require mandatory ingredient lists. After all, visit any pub and you discover drinking beer is a national passion. This country of five million consumes a million pints a day. Germany comes the closest to identifying what's in the brew. The Act of Purity dictates only the basic four ingredients. It's the oldest consumer law in the world still on the books, written to protect beer drinkers of the16th century from additives.

Four centuries later, the New World is still trying to figure it out. In Washington, the issue has made to the floor of Congress. But not in Canada, much to the chagrin of aficionados like Jamie McKinnon, well-known author and beer critic.

Jamie McKinnon

"Beer is not meant to be a widget or an industrial product, which it's increasingly resembling in its mass market guise, McKinnon says. "Beer is a food. It's a gentle food."

And because it's also a highly prized food, worth billions of dollars a year in Canada, the recipes for making the most popular brands remain hush-hush.

According to Labatt spokesman Bob Chant, his company -- like rival Molson -- sticks to a handful of ingredients. Just don't ask for the recipe.