At the CNBC debate, Ben Carson tried to argue that he never had anything to do with an extraordinarily shady supplement company.

That is nonsense. The truth is that Carson had a years-long relationship with Mannatech—a company that pimps pseudoscience and allegedly engaged in unethical marketing practices.

Jim Geraghty broke this story months ago at National Review. Mannatech is a supplement company that sells so-called glyconutrients. Its representatives have suggested the product can treat autism, cancer, AIDS, and multiple sclerosis. Spoiler: “Glyconutrients” do not cure cancer, and no credible researcher or doctor says they do.

In fact, if Carson had glanced at the company’s Wikipedia page, he would have seen that one top glycobologist said these “glyconutrients” have no identifiable impact on the human body besides making you pass more gas. Seriously.

The state of Texas sued the company, which settled in 2009 by paying $4 million to Texas customers, promising that its representatives would stop saying its products could “cure, treat, mitigate or prevent any disease.” The company didn’t admit to any wrongdoing.

When Geraghty reached out to Mannatech about their relationship with Carson, spokesman Mike Crouch said this: “We appreciate his support and value his positive feedback as a satisfied customer.”

But Mannatech doesn’t just sell bad medicine. At least one lawsuit alleged it uses astonishingly unethical marketing practices to do so. In 2004, a mother sued after trying to use the company’s products to help her 3-year-old son, who suffered from Tay-Sachs disease. The suit alleged that the company showed naked pictures of the boy—which his mother said she shared with representatives of the company in confidence—to suggest to hundreds of seminar attendees as evidence that its products worked. The worst part? The son died while using Mannatech supplements, according to the suit. The company confidentially settled that suit in 2005 for $750,000.

Anyway, Carson addressed at least three of the company’s annual conferences, according to National Review. His image appeared on its website’s homepage. He praised its fart-inducing glyconutrients on PBS. And as recently as last year, he suggested the company had tapped into God’s secrets for good health.

“The wonderful thing about a company like Mannatech is that they recognize that when God made us, He gave us the right fuel,” Carson said in a video touting the company’s products.

“Many of the natural things are not included in our diet,” he continued. “Basically what the company is doing is trying to find a way to restore natural diet as a medicine or as a mechanism for maintaining health.”

As part of his characteristically lackluster debate performance, Carson tried to distance himself from Mannatech on Wednesday night when a CNBC moderator pressed him on that relationship.

“I didn’t have an involvement with them, that’s total propaganda,” he said, betraying a total misunderstanding of what the word “propaganda” means. “What happens in our society, total propaganda. I did a couple of speeches for them, just for other people, they were paid speeches. It is absolutely absurd to say that I had any kind of relationship with them. Do I take the product? Yes. I think it’s a good product.”

To be fair, it is a good product—if you like to fart.

By the way, this isn’t the first time Carson has touted pseudoscientific nonsense on the presidential debate stage. At the last debate, he touted the debunked idea that parents should disregard the Centers for Disease Control’s recommended vaccine schedule and “space out” their children’s vaccinations. As The Daily Beast detailed, that suggestion is a species of anti-vax trutherism. It’s less pernicious than full-on vaccines-cause-autism trutherism, but it is trutherism nonetheless. “Spacing out” your kids’ vaccines has one effect, and one effect only: increasing the amount of time your kids are vulnerable to the diseases from which those vaccines inoculate them.