Some Marketplace reports about vitamins and supplements published in November contained incorrect information, CBC has learned.

Last fall, Marketplace commissioned lab testing for samples of fish oil, vitamin C and protein powder supplements to see if consumers are actually getting what they pay for.

Based on those test results, Marketplace reported that Emergen-C and two protein powders: GNC Lean Shake 25 and Cytosport Muscle Milk failed to live up to label claims.

  • Watch the full behind-the-scenes investigation on this story on CBC's Marketplace Friday at 8 p.m., 8:30 p.m. NT.

However, subsequent re-testing of the samples has found that the lab results and analysis provided to Marketplace were incorrect, and that there is no evidence of problems with those products.

The original lab tests were performed by an independent lab in Michigan, which is ISO-17025 accredited,  registered with the U.S. Food and Drug Administration, and used by the supplement industry.

The lab was recommended by Neil Thanedar, co-founder and CEO of LabDoor, a company that has products tested and makes those results public to help guide consumers about vitamins and supplements.

LabDoor's investors and partners include Rock Health, a San Francisco-based venture fund that invests in health-care research, and the Mayo Clinic.

Thanedar agreed to analyze the test results for Marketplace.

The supplement companies strongly disputed those results.

When Marketplace learned there might be a problem with one of the tests, CBC re-tested some of the products at other independent, accredited labs. None of them found problems with the samples.

Emergen-C, protein powders cleared

In his original analysis, Thanedar concluded that the popular vitamin C supplement Emergen-C, made by Pfizer, contained only one third of the 1,000 mg of the vitamin that the package promised.

However, the re-testing concluded that there is no issue with the amount of vitamin C in that sample of Emergen-C.

Marketplace also tested popular brands of protein powder for evidence of "spiking," in which manufacturers use filler because it is cheaper.

Two brands in the initial testing and analysis — Cytosport's Muscle Milk and GNC's Lean Shake 25 — appeared to have evidence of spiking. The GNC product appeared to be more than half spiked.

Subsequent re-testing of both brands of protein powder found no evidence of spiking.

Re-testing of fish oil confirmed the initial result that some fish oil was rancid.  

Re-testing shows no problems

Thanedar admits some of the lab results were wrong.  

Neil Thanedar

“We’re apologizing to your audience. And we’re promising to improve ourselves,” Neil Thanedar told Marketplace’s Erica Johnson. (CBC)

"We're apologizing to your audience. And we're promising to improve ourselves," Thanedar told Marketplace's Erica Johnson.

"We've done this test (of protein powder) more than a hundred times. And we haven't seen an issue like this. And it's incredibly frustrating for us because this is all the work we do," he says.

"We're constantly testing products, this is our day-to-day job. And there's no one we can put that blame on other than us."

While Thanedar admits some of the lab results he provided to Marketplace were flawed, he was still unable to explain how the mistakes were made.    

Stuart Phillips, a scientist at McMaster University who studies the effects of protein supplements on humans, says: "There are all kinds of reasons why things can go wrong.

"Like anything else in life, I think when a lab gets something wrong, human error, contaminated dirty glassware, machine malfunction."

Phillips hopes this error doesn't undermine public trust in lab testing, "because it undermines everybody else, industry and scientists, researchers alike, who do this sort of thing on a day-to-day basis."

Marketplace evaluating testing protocols

In response to the discovery, Marketplace is evaluating its protocols around the use of lab testing.

In a report to be broadcast on Marketplace on Friday at 8 p.m., (8:30 p.m. NT), host Erica Johnson says, "We regret giving you incorrect information and any harm it may have caused the companies in our report. We're sharing this story with you because your trust is important to us. We work hard to make sure we deliver the kind of journalism you've come to expect."