Exactly how bad is salt?

The words being hurled are strong: Toxic. Poison. Forgotten killer. Public Enemy No. 1. They are fierce battle cries against salt — and they are getting louder and stronger.

The Centre for Science in the Public Interest, one of the not-for-profit movers and shakers in the growing anti-salt movement, says as many as 15,000 Canadians a year are dying prematurely because of “excessive sodium consumption."

Similarly staggering numbers in the United States prompted the American Medical Association to recommend this summer that the Food and Drug Administration strip salt of its “generally recognized as safe" status and strongly regulate it as a food additive, a category that includes food dyes and monosodium glutamate (MSG).

Just this month, a group of about 200 health experts from universities across the globe launched a similar campaign called World Action on Salt and Health, whose aim is to reduce dietary intake to less than five grams daily in an effort to lower blood pressure globally. And the World Health Organization met in Paris last week to discuss a series of recommendations it will release in November as it, too, throws down the gauntlet.

One of Canada's anti-salt activists, Bill Jeffrey of the Centre for Science in the Public Interest in Ottawa, said that “if 15,000 Canadians are dying prematurely every year because they're consuming too much salt, I don't think there's any pejorative word strong enough to describe it."

In fact, one of the country's leading experts in hypertension has gone so far as to say that if salt were introduced as a new substance today, it would not be deemed safe for human consumption.

“It would be very closely regulated," said Norm Campbell, professor of medicine at the University of Calgary and the Canadian Institutes of Health Research chair in hypertension prevention and control.

These salt critics argue that high-sodium diets are directly linked to high blood pressure. And high blood pressure greatly increases the risk of heart attack and stroke.

More than 80 per cent of the sodium ingested by North Americans comes from processed foods, critics say, because pinches and dashes of it are everywhere — breads, cheeses, breakfast cereals, even salads.

Health Canada's dietary guidelines say that the average adult should eat less than 2,300 milligrams of sodium a day, but the limit could be as low as 1,300 for people with high blood pressure, those at higher risk for high blood pressure such as blacks and those over 50. Yet on average, Canadians eat more than 3,500 milligrams of sodium a day, with less than 10 per cent of it added at the table. (By weight, salt is composed of 40-per-cent sodium and 60-per-cent chloride. So a teaspoon of table salt contains 2,300 milligrams of sodium.) There is disagreement, however, between the warring sides.

The debate isn't so much over the link between salt and blood pressure, but rather to what degree they are linked — and whether other factors may play a more significant role in high blood pressure. There simply isn't enough science that links high-salt diets directly to heart attacks and strokes to call for a blanket recommendation for the general population.

“They're arguing to change the dietary habits of 99 per cent of the Canadian population based upon changes in blood pressure and the extrapolation that a reduction in blood pressure will make me healthier," said Alexander Logan, a professor of medicine at the University of Toronto and an expert in kidney disease and hypertension.

“But if I switch to a low-salt diet, will I live a day longer? Will I feel better? Will the quality of my life improve? Those answers aren't available yet, so why are we rushing to implement public policy on it?" asked Dr. Logan, who says he consults for the salt industry but does not get paid for his services.

His views are echoed by the head of the Salt Institute, the trade group that speaks on behalf of salt producers. Richard Hanneman argues that salt-intake levels by North Americans have remained relatively unchanged for 100 years, so having more low-sodium products available won't mean people will stick to eating them.

“There's a human physiology here. Humans have a natural intake level for salt and it's partly cultural but it is hard to change," Mr. Hanneman said, adding that's why even though some companies have come out with low-sodium products, they have ended up pulling them off grocery shelves because of poor sales. As far as he's concerned, “the science is on our side, not theirs."

But one of the world's leading experts on the issue, Stephen Havas of the American Medical Association, sees it differently. The global movement against salt “is the single most concentrated focus ever given to an issue in the nutrition arena," he said.

As the vice-president for science, quality and public health at the AMA, he has been putting pressure on the U.S. Food and Drug Administration to take a second look at salt and the health problems associated with it.

“There is a huge amount of literature indicating that excess sodium is killing and disabling huge numbers of people worldwide," he said, adding that humans need “almost no salt" to survive, because all the salt we need is found naturally in food before it's processed.

In fact, he continued, Canadians and Americans are probably consuming 10 times as much salt as is necessary without knowing it because most of the salt in processed foods cannot be tasted. People could reduce their sodium intake by 50 per cent and get used to it “within weeks."

The salt industry argues this would compromise taste. But Dr. Havas says it has more to do with profits. By having saltier foods, people consume more liquids — usually in the form of soda or alcohol at restaurants — and the food industry cashes in on this.

“That's why when you go into most bars, they'll have salted peanuts and pretzels there. I don't think that's an accident," he said. “On some level, they know people are going to drink more when they have more salt in their products. It's deliberate."

This debate has been boiling in the United States and certain European countries for years. But it's only this year that it's coming to a head in Canada.

While Health Canada's Bureau of Nutritional Sciences says it has not been lobbied to regulate the amount of sodium in processed and restaurant foods here, it says it “recognizes that sodium is a very significant issue and will indeed provide advice regarding consuming food with little or no added salt," spokesman Paul Duchesne said. Health Canada will be putting out a new food guide early next year with the recommendations, but it is not currently considering changing the way salt is regulated as an ingredient and changing it to an additive.

That could very likely change, and soon, said Prof. Campbell, the hypertension expert in Calgary.

Different political climates, smaller budgets and no real leaders on the issue are all reasons Canada is “late into the game," he said. But the movement has finally arrived north of the 49th parallel.

So who's in charge? “Well, I guess I am," Prof. Campbell said.

He will be heading the Canadian initiative, which aims to examine what has been successful in other countries, to determine how many Canadians are affected by high sodium intake and at what cost to the government, and to ensure that scientific information is available to counter the “misinformation that some companies are promoting."

But Canada will need to go beyond recommendations now that it has its own cast of key players. It needs to deal with salt just like it did trans fats, argued Stephen Samis, director of health policy at the Heart and Stroke Foundation of Canada.

“We need to incorporate health organizations, consumer organizations, government reps, industry and really try to work toward a practical and evidence-based solution that would help protect the health of Canadians." It would take time to put together a task force and write up a report, Mr. Samis said, but the outcome could be “tremendous."