​Popular “detox” cleanses, including one promoted by Dr. Mehmet Oz on his popular TV show, are unproven and ineffective, a CBC Marketplace investigation reveals.

Marketplace teamed up with some sorority sisters at Western University to test Dr. Oz’s 48-hour cleanse, which he promotes on his website and his much-watched television show. The show also investigated two other trendy treatments that claim to “detoxify” the body.

Watch The Marketplace episode Detox Challenge airs Friday at 8 p.m. (8:30 p.m. in N.L.).

Despite bold promises that the treatments would purify, detoxify and boost energy and optimize organ function, the cleanses lacked any scientific evidence of efficacy, or clear idea of what toxins they would actually diminish.

Consumers are inundated by headlines that say our bodies absorb a wide variety of environmental toxins on a daily basis, from mercury in fish to carpet off-gases to chemicals in our drinking water. Detox programs are often advertised as a remedy for this.

Detox cleanses are the darlings of celebrities including Gwyneth Paltrow, who publishes cleanse diet recipes on her website Goop, as well as Demi Moore, who actively promotes the use of leeches as a detoxifying treatment.

“In looking at the medical literature on these things, there has never been a properly conducted scientific investigation of any of these treatments that I’ve been able to find,” Dr. George Dresser, a toxicologist, pharmacologist and an internal medicine specialist at London Health Sciences Centre, told Marketplace co-host Tom Harrington. “It’s an intensely popular topic. And it’s popular because people are interested in a quick fix to health ”

In addition to Dr. Oz’s cleanse diet, the show also looked at two other detox programs and examined the science behind the treatments. The full investigation, Detox Challenge, airs tonight at 8pm (8:30pm NT) on CBC Television.

Dr. Oz advice controversy

Dr. Oz -- who is the vice-chair and professor of surgery at Columbia University, as well as the host of the popular Dr. Oz Show -- markets his 48-hour cleanse as “the ultimate detox solution,” which promises to “revitalize you from the inside out“ and boost liver and kidney function. Dr. Oz does not charge money for the cleanse recipes; they are based on ingredients you can buy at the grocery store.

CBC Marketplace teamed up with sorority sisters from Western University to test the effects of Dr. Oz's cleanse. (CBC)

A group of sorority sisters from Western University volunteered to help Marketplace test the cleanse. Half of the group participated in the Dr. Oz cleanse, which required that the students observe a strict diet and refrain from alcohol and caffeine, and not eat any food after 7 p.m. They also drank detoxifying teas and took soothing baths as prescribed by the diet, while the other students ate and drank normally.

To test the efficacy of the cleanse, all students had their liver and kidney functions tested both before and after the 48-hour period. At the end of the 48-hour period, however, Dr. Dresser was unable to detect any physiological benefit at all, or even tell which students had participated in the cleanse.

Dr. Dresser told Marketplace that he doubted that any detox cleanse would have a real benefit, regardless of the duration.

Despite a CV that boasts degrees from Harvard and the University of Pennsylvania medical school, Dr. Oz has been the target of growing criticism from fellow medical and science professionals for his promotion of products and methods that lack evidence. “Given his education and influence,” wrote Erin May on the Harvard University science research blog Policylab, “there’s no excuse for the unsubstantiated claims and sensational language that is so pervasive on his show.”

In response to some of these criticisms, a spokesperson for Dr. Oz told one newspaper: “Our audience are not scientists, and the show needs to be more lively than a dry scientific discussion.” Dr. Oz declined to be interviewed for the Marketplace story.

Cleanses lack evidence

Detox cleanses, programs, supplements and scrubs line the shelves of health food and drug stores and fuel a multi-billion dollar industry.

Dr. Dresser, who is also a professor of toxicology and pharmacology at Western University, worked with Marketplace to test Dr. Oz’s cleanse and says that many detox treatments on the market are vague about what they do or how they work.

“It’s sometimes difficult to know exactly what toxins they’re talking about,” he says.

He says that hype about detoxifying “superfoods” is not supported by science. “There is no evidence that I can see that there are specific foods that are better at detoxifying than others. I think that the value of food is its nutrient value. And I think that we should all be consuming good-quality food. But in terms of one food being able to detoxify or enhance elimination of noxious substances in your body, I don’t think there’s any evidence for that.”

While the Dr. Oz cleanse had no medical benefit, Dr. Dresser says that it is not dangerous. “The good news, I suppose, is that the detox treatment didn’t result in a negative change in health status. But there was also no improvement.”

Dr. Dresser says that the detox trend is fuelled by our desire for a quick-fix solution to health.

On the topic of popular detox cleanses, Dr. George Dresser says, "there has never been a properly conducted scientific investigation of any of these treatments that I’ve been able to find." (CBC)

“From a health-behavior standpoint,” he says, “I think that if you read any claim that says, in two days or seven days, or thirty days, ‘I can substantially change your health status,’ I think you should be skeptical.”

“I think that there’s a lot of these things, like the detox treatments, where there isn’t substantial evidence for benefits,” he says. “And yet people are using them. And, in a way, that’s an indictment of us in the medical system for not communicating better what we know.”

In 2009, the UK group Voice of Young Scientists published The Detox Dossier, a report on popular detox treatments.

The group found companies that market detox products were unable to point to evidence that supported their claims, or even come up with a coherent definition of what “detox” means. In addition: “many of the claims about how the body works were wrong and some were even dangerous.”

As one of the report’s authors, biologist Harriet Ball, wrote: “Detox is marketed as the idea that modern living fills us with invisible nasties that our bodies can’t cope with unless we buy the latest jargon-filled remedy.”

Dr. Dresser says that our bodies already cleanse and detoxify our bodies quite effectively.

“The liver is incredibly efficient at getting rid of those noxious substances. The kidneys do a great job at eliminating many toxins that are soluble in water,” he says.

“We have everything we need inside of us right now.”