Mehmet Oz, the celebrity heart surgeon who announced he will run for Pennsylvania’s open U.S. Senate seat, is among the best-known doctors in the country.

But on his popular television program, The Dr. Oz Show, the 61-year-old often offers misleading — or downright untrue — medical advice.

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Though he has used his platform to promote well-accepted health advice — for instance, hosting a renowned scientist to debunk the myth that the mRNA COVID-19 vaccines alter our DNA — he’s been widely criticized by doctors, scientists, and lawmakers for peddling pseudoscience.

Here are some of his more questionable claims that have earned the Penn-educated, NY Presbyterian-Columbia Medical Center cardiothoracic surgeon such notoriety:

Hydroxychloroquine as a COVID-19 treatment

Oz was among the medical experts to tout the benefits of hydroxychloroquine, the malaria drug pushed by former President Donald Trump as a treatment for COVID-19, despite insufficient evidence. After studies found the drug did not provide any benefit for treating COVID-19, Oz dialed back his endorsement, saying people should wait for more substantial evidence from trials.

Risk of sending children back to school

Oz has used his national platform to give credence to COVID-19 misinformation and fuel politicization of the pandemic.

In April 2020 he faced backlash after arguing that schools should reopen because doing so “may only cost us 2% to 3% in terms of total mortality” of the population. He apologized on Twitter and said he misspoke.

Yet in a candidacy announcement posted to his campaign website, Oz again suggested the government had overblown the severity of COVID-19, unjustly limiting personal freedom.

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He says Americans were “patronized and misled instead of empowered” and “told to docilely lock down and let those in charge take care of the rest.”

“Elites with yards told those without yards to stay inside — where the virus was more likely to spread. And the arrogant, closed-minded people in charge closed our schools, shut down our businesses and took away our freedom,” he says on his website.

In the candidacy announcement, Oz says that COVID-19 critics, including unnamed Nobel laureates, were “canceled,” that doctors were prohibited from prescribing legal medications “for the first time in history,” and that his own efforts to fund clinical trials for drugs that could help treat COVID-19 were “banned.”

His campaign did not respond to a request for additional details about the Nobel laureates, restricted medications, and clinical trials.

Green coffee as a ‘magic bean’ for weight loss

Oz has featured several products on his show designed to “melt belly fat” with little evidence that they work. In 2014, he was hauled into a U.S. Senate committee hearing to address his claims that green coffee extract was a “miracle” weight-loss supplement.

Oz told senators he promoted such products because he felt his job was “to be a cheerleader for the audience.”

“When they don’t think they have hope, when they don’t think they can make it happen, I look everywhere, including in alternative healing traditions, for any evidence that might be supportive to them,” he said.

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A small study in India had found the extract helped people lose weight quickly, but it was later retracted after a Federal Trade Commission complaint that the green coffee manufacturer Applied Food Sciences had paid researchers to conduct the study and that data had been manipulated.

Companies that advertised green coffee’s weight-loss benefits based on the flawed study agreed to a $9 million settlement with the FTC to refund 200,000 consumers who had bought the products based on false advertising.

The companies used their spots on Oz’s show to further promote their products, according to the FTC.

Garcinia cambogia extract as weight-loss miracle

Oz also helped popularize a supplement made from garcinia cambogia, a tropical fruit that resembles a small, yellow pumpkin. The hydroxycitric acid found in the fruit’s rind is supposed to slow fat buildup and increase serotonin, making people feel less hungry. But studies have not found the extract to have any significant effect on weight loss.

Regardless, Oz promoted the product on his show as a “revolutionary fat buster” that could help people lose weight without diet or exercise.

Critics have speculated that Oz has financial ties to the supplements he peddles on his show. In a 2015 letter urging Columbia University to rescind Oz’s faculty appointment, a group of doctors accused him of “an egregious lack of integrity by promoting quack treatments and cures in the interest of personal financial gain.” The letter did not offer any evidence that Oz accepted money in exchange for promoting a product, and the television host has said he does not earn commission from any product featured on his show.

Philadelphia’s opioid crisis is ‘hell’

Oz came to Philadelphia in 2017 to film a segment on the city’s El Campamento, a former heroin camp along a Conrail-owned strip of land in Kensington. He called the camp the “festering epicenter of the heroin crisis,” drawing national attention and outrage. Later that summer, Philadelphia officials dismantled the encampment — but residents and advocates have criticized the clearance, saying the city didn’t offer people with addiction adequate treatment or housing options, and contending the clearance contributed to larger, more visible encampments throughout the neighborhood.