After Oprah delivered her epic Golden Globes speech on Sunday, #Oprah2020 was suddenly a thing.

Everyone from Ivanka Trump to Ron Howard praised her inspiring oratory, and celebrities like Lady Gaga said they’d vote for her if she were to run for president. Even hard-nosed political observers, including Nate Cohn and Nate Silver, pointed out she would be a real contender.

Oprah has reportedly denied any interest in the White House, but that hasn’t stopped people from wondering what an Oprah presidency could look like — and what scrutiny she’d face if she really harbors political ambitions.

Since people are clamoring for her to run as a solution to our country’s problems, we wanted to highlight one area in which the broadcaster, billionaire, and philanthropist has a pretty dubious record: science.

During her 25-year reign as host of The Oprah Winfrey Show, from 1986 to 2011, Oprah repeatedly showed a weakness for crackpots and quack medical theories. One could even argue that she’s one of the most powerful enablers of cranks on the planet. Here’s a quick rundown of some of her worst assaults on reason and scientific thinking.

Oprah made Dr. Oz a celebrity

In 2004, Dr. Oz made his first appearance on The Oprah Winfrey Show, where he was referred to as “America’s Doctor” (a moniker he trademarked). As a regular medical expert on Oprah, he used the platform to back a range of questionable health practices, including lending credibility to the Brazilian spirit medium and well-known huckster ”John of God.”

The Oprah seal of approval helped Oz get his own show by 2009. Her instincts about his potential were good, in a sense: Oz is immensely popular, and his media empire now extends to books, magazines, radio, websites, and, of course, TV. But on The Dr. Oz Show, the cardiothoracic surgeon has regularly promoted bad science and bogus health advice.

In 2014, Oz was called before a Senate subcommittee on consumer protection. He was asked by the senator in charge, Claire McCaskill, to explain his use of “flowery” language to champion weight loss fixes that don’t actually work. She then admonished him for endorsing a rainbow of supplements as potential “belly blasters” and “mega metabolism boosters.” As McCaskill put it, “The scientific community is almost monolithic against you in terms of the efficacy of the three products you called ‘miracles.’”

In 2015, the Federal Trade Commission found that Oz’s producers did the scantest research on the show’s guests, which allowed modern-day snake oil salesmen to appear on air hawking bogus products. That same year, a group of professors, scientists, and doctors argued that the show was so misleading that Oz’s professor position was incompatible with his on-air work.

Oz has also shared the stage with vaccine deniers, and activists like “Food Babe” Vani Hari (known to scientists as “the Jenny McCarthy of food”). At the height of the Ebola panic last year, Oz suggested the virus could go airborne — even though there was universal agreement among virologists that the pathogens have never behaved that way.

All this didn’t turn Oprah off of Oz. He remains a regular contributor to her widely read O magazine and her website, and she still appears on his show.

Oprah created “Dr.” Phil

Despite his medical shenanigans, Dr. Oz has an actual medical degree to his name. Dr. Phil, on the other hand, doesn’t (he holds a doctorate in psychology and is not a licensed psychologist). But that minor detail didn’t stop Oprah from using the “Dr.” moniker at the front of his name.

McGraw also got his start on Oprah’s show, after meeting the TV star while working with her as a consultant when she was being (unsuccessfully) sued for making negative statements about the beef industry in 1995. By the late 1990s, Dr. Phil started appearing on her show as a life coach, and in 2002 he launched his own eponymous show.

Like Dr. Oz, McGraw has been censured for using his celebrity and his show for ethically dubious practices. In 2016, he was criticized for peddling diabetes pharmaceuticals through paid sponsorships that were masquerading as friendly advice about a disease from a trusted source.

And last December, a Stat investigation uncovered some unethical behind-the-scenes practices on the show, including giving vodka to a guest who was battling alcoholism and asking other guests with severe drug addictions to buy drugs on the street — all for the purposes of entertainment.

“It’s a callous and inexcusable exploitation,” Dr. Jeff Sugar, an assistant professor of clinical psychiatry at the University of Southern California, told Stat. “These people are barely hanging on. It’s like if one of them was drowning and approaching a lifeboat, and instead of throwing them an inflatable doughnut, you throw them an anchor.”

Like Dr. Oz, McGraw is still a regular contributor to O magazine, and the Dr. Phil show still airs on the Oprah Winfrey Network.

Oprah gave Jenny McCarthy a platform to spread hogwash about vaccines

Actress, Playboy model, and pseudoscience peddler Jenny McCarthy has been an ardent anti-vaccine advocate. She helped propel the discredited British doctor Andrew Wakefield, who has argued that vaccines cause autism based on his own fraudulent research, to fame. (McCarthy even co-authored an anti-vax book in 2011 with Wakefield, titled Callous Disregard.) In the media, she’s claimed that vaccines gave her son Evan autism, and that she was able to “cure” him through a special diet and supplements.

Of course, the notion that vaccines cause autism has never been supported by science. But Oprah gave McCarthy a vast audience via her TV show in 2007. Science journalist Seth Mnookin, who covered this meeting of the minds in his book The Panic Virus, reported that Winfrey “praised McCarthy’s unwillingness to bow to authority, her faith in herself, and her use of the Internet as a tool for bypassing society’s traditional gatekeepers.” Here’s an excerpt from the interview transcript:

MCCARTHY: First thing I did — Google. I put in autism. And I started my research. WINFREY: Thank God for Google. MCCARTHY: I’m telling you. WINFREY: Thank God for Google. MCCARTHY: The University of Google is where I got my degree from. ... And I put in autism and something came up that changed my life, that led me on this road to recovery, which said autism — it was in the corner of the screen — is reversible and treatable. And I said, What?! That has to be an ad for a hocus-pocus thing, because if autism is reversible and treatable, well, then it would be on Oprah.

Days after that Oprah appearance, McCarthy was invited on Larry King Live and Good Morning America to spread her anti-vaccine message even further. Between the three shows, she reached between 15 million and 20 million viewers with her anti-vaccine message, Mnookin estimated.

To this day, the episode featuring McCarthy, “Mothers Battle Autism,” is featured on Oprah’s website, without any correction or acknowledgment of the problems with McCarthy’s claims.

For more about Oprah’s relationship with junk science, read David Gorski’s great rundown on his blog Respectful Insolence. You can also read my explainer about Andrew Wakefield and my feature about Dr. Oz’s rise to fame.