Testing by Vega, previously known as Sequel Naturals, showed the antibiotic chloramphenicol present in its Vega One Vanilla Chai (437 g and 874 g formats) and Vega Sport Performance Chocolate products.
The drug, found in the enzymes used to make the shakes, is a naturally-occurring antibiotic, but has been linked to a risk of aplastic anemia, a rare blood disorder which can be fatal.
In an online response to Health Canada, Vega President Charles Chang claims the levels of chloramphenicol present in the nutritional shakes are too low to have any effect.
"The enzyme blend in Vega One is less than one per cent of our formula, so the trace amounts of chloramphenicol are so minute, they pose no risk to consumers," says Chang in the video.
Chang also claims there has never been a case of the disorder resulting from less than a therapeutic oral dose of the drug.
"You would have to take over 100 million servings of Vega One to get a single therapeutic dose of chloramphenicol. That's 100 million servings a day.
"We stand by our belief that Vega products are completely safe...and we continue to work with Health Canada to revise their advisory as the science supporting the safety of consuming chloramphenicol at these trace levels is indisputable."
Risk not related to dose
Health Canada said it is impossible to predict who will develop aplastic anemia after taking the antibiotic and the risk does not seem to relate to the dose taken.
Other side effects that can be associated with chloramphenicol include allergic reactions in people who have sensitivity to the medication, and effects on the bone marrow leading to decreased blood cells.
Chloramphenicol should not be used by pregnant or lactating women.
Health Canada says it works with the health-product industry to ensure hazardous products are pulled from the marketplace, but recalls are initiated by importers and manufacturers themselves.
Problems for Vega products
Vega products have been subject to recalls before. The Canadian Food Inspection Agency issued two recalls of Vega-brand snack bars earlier this year, saying the bars might contain milk — which was not declared on the label.
In February, Vega voluntarily recalled Vega One French Vanilla nutritional shake, after tests by Health Canada showed bacteria that could be risky to people with weakened immune systems
However, Chang told the CBC that Vega will not be recalling the nutritional shakes in question this time around and says the company is being unduly persecuted.
"That's the worst thing that could possibly happen because whether it's a real issue or not — look what happens. It's like blackballing us without having the information."
In his online video, Chang says it has sourced a new supplier of enzymes free of chloramphenicol and has stopped distributing any products containing the drug.
The company is also offering a full refund to any customers wishing to return the shakes in question.