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Supplements, including herbal remedies and vitamins, are frequently approved for sale in Canada with only minimal review and based on what Health Canada acknowledges is "weak evidence," a fifth estate investigation shows.

The investigation, which examined the safety and risk of dietary supplements, also found that government oversight has been eroded under pressure from the supplements industry, which has been anxious to cash in on the latest health-care trends.

Health Canada statistics show that it now approves more than 90 per cent of applications to sell new natural health products. And under updated rules, products can be approved in as little as 10 days.

Watch "Magic pills" on CBC TV the fifth estate Friday at 9 p.m., 9:30 NT

However, several recent studies have raised concerns about the quality and safety of many supplements.

For example, research in New Zealand published earlier this year found that 83 per cent of fish oil supplements tested exceeded maximum industry standards for rancidity. And recent tests by CBC's Marketplace showed that four of seven fish oil supplements tested showed signs of rancidity.

Some leading researchers also say there is mounting evidence that many of the most popular supplements don't live up to their claims and could even be dangerous.

"It you take a megavitamin you actually can hurt yourself," said author and University of Pennsylvania infectious disease specialist Dr. Paul Offit. "You actually can increase your risk of cancer, increase your risk of heart disease."

Failing consumers

Michael Kruse, chairman of the advocacy group Bad Science Watch, said that by pushing natural health products through the approvals process, Health Canada is failing Canadian consumers.

"People are spending millions of dollars on these products every year and most of them have no evidence of efficacy," he said.

"They're being duped by a manufacturing lobby that really is focused on profit and not on the person's health."

Michael Kruse is chairman of the advocacy group Bad Science Watch and says Health Canada is failing Canadian consumers by pushing natural health products through the approvals process too quickly. (CBC)

About three-quarters of Canadians regularly take natural health products such as vitamins, minerals, fish oil and herbal remedies, a 2010 Ipsos-Reid survey found.

Annual sales in Canada total about $1.4 billion, and supplements must be approved by Health Canada's Natural and Non-Prescription Health Products directorate before they go on sale.

The rules were established in 2004 in response to concerns about the potential dangers of unregulated products and to consumer demand for greater choice.

Industry spokesperson Helen Long, president of the Canadian Health Foods Association, describes Canadian oversight of supplements as "one of the strongest regulatory frameworks in the world."

"Before a product even goes to sale you must provide proof that your product works, that it has quality ingredients, that it's effective, that it does what it says it will do on the bottle," said Long.

But the fifth estate's investigation raises questions about how Health Canada enforces those rules.

Health Canada's 'new approach'

In the early days of the directorate, Health Canada statistics show it was difficult to get products approved. Bureaucrats rejected more than half of the applications they received.

Valerie Assinewe, a former scientific evaluator and head of monograph development with Health Canada's Natural Health Products Directorate, said many applicants could not provide the evidence Health Canada required, and that bureaucrats engaged in lengthy negotiations to help manufacturers get their products approved and into stores.

"I found often that the Natural Health Products Directorate seemed to be an advocate for the manufacturer," said Assinewe, who retired because of budget cuts in 2013.

Valerie Assinewe, a former scientific evaluator and head of monograph development with Health Canada's Natural Health Products Directorate, says many applicants could not provide the evidence Health Canada required. (CBC)

Lengthy reviews created a backlog, and in the fall of 2012 Health Canada went on a cross-country "road show" to consult with the industry.

Briefing documents presented at those meetings and obtained by the fifth estate show that Health Canada was aware of significant problems with the quality of natural health products.

One document says that 40 per cent of complaints to inspectors responsible for enforcing the regulations were about natural health products, and that 40 per cent of those were about poor quality of the products.

Common complaints included contamination, purposeful adulteration, incorrect strength and incorrect identity, the document says.

Even so, Health Canada proposed a "new approach" to approving natural health products that would be "quicker and clearer," and which left it up to manufacturers to ensure quality.

Health Canada also said that for products that made general health claims it would accept "a totality of weak evidence" showing they were safe and effective.

The document says the criteria would be applied to products meant for "self-diagnosable, self-treatable, self-resolving conditions." It does not define what is meant by weak evidence, but says text books, epidemiological studies and observational studies could be used.

Many could also be approved in as little as 10 days, the document said.

Kruse, who attended one of the sessions in Toronto, described the 10-day timetable as "indicative of the manufacturer-focused, lobbyist-focused process that Health Canada has implemented."

He said some manufacturers argued that products should be approved even more quickly.

"There was a small manufacturer who stood up and said 10 days is too long. We want to be able to respond to what's called the Dr. Oz effect, where Dr. Oz has raspberry ketones for example on his show and says 'these are the new miracle product.'

"We want to have those products on our shelves within a couple days, because that's when people come to our store to buy them after the product."

New York takes action

The new proposals were implemented in early 2013. Since then, Health Canada has approved more than 90 per cent of applications for natural health products.

At the same time, Health Canada has decided not to take action on independent evidence that shows problems with contamination and adulteration of herbal supplements.

University of Guelph botanist Steven Newmaster and his team conducted DNA tests on 44 herbal supplements bought in Canada and the U.S.

Health supplements are a $1.4-billion industry in Canada, but product testing is questionable. (CBC)

Their study, published in the journal BMC Medicine in October 2013, found that nearly 60 per cent of the supplements contained ingredients not listed on the label and 32 per cent were outright frauds.

Alarmed by Newmaster's results, New York Attorney General Eric Schneiderman commissioned his own DNA tests of supplements sold by four major chains in the U.S.

His study produced even more disturbing results, and Schneiderman ordered the retailers to stop selling the supplements.

However, Newmaster said Health Canada has never contacted him about his study.

In an email statement, a Health Canada spokesperson said it reviewed Newmaster's work, but, because he didn't list the ingredients and brands tested, decided no action was necessary.

Newmaster said he did not identify the products tested because his study was a double-blind study in which the investigators weren't told which brands they were working on.