Is green coffee bean extract a miracle cure for obesity? Are raspberry ketones or saffron extract magic weight loss ingredients? Regardless of the veracity of these claims, the celebrity physician Dr. Mehmet Oz has endorsed those and many products to the viewers of The Dr. Oz Show. This has created “the Oz effect” of increased interest—and may perhaps have boosted sales.

Zijun Shi of HKUST and colleagues investigated the effect of Dr. Oz’s recommendations on coverage of the hyped ingredients in the main consumer information channels. They also examined the market response to Dr. Oz’s “hype news,” a phenomenon defined as “information that is taken out of context, exaggerated, and overgeneralized,” but which is based on a grain of truth to become “a pernicious form of information distortion.”

To assess the effects of hype news on information about over-the-counter (OTC) health products containing the ingredients promoted by Dr. Oz, the researchers used “machine-learning based text analyses and causal identification strategies to present empirical evidence of the media hype” following his endorsement. They analyzed the responses of reputable news media; research by experts; reviews on e-commerce websites; and online discussions on sites such as Quora and Facebook.

These channels all have credibility issues, the scientists note. Journalists “may not have access to the necessary rigorous data or research expertise,” and must compete for views online, an incentive to hype an ingredient. Medical researchers have the required expertise, but “peer-reviewed journals usually have long publishing cycles,” the authors write, “and researchers might not be able to get the necessary data.” Consumers lack expertise, so it is unclear whether they “amplify or mitigate the misinformation from Dr. Oz” in their reviews and discussions––a criticism the researchers also level at the news media.

The writers set out their findings for intensity––essentially the volume of coverage generated by Dr. Oz mentioning the ingredient––and whether it amplified or mitigated the hype. They looked for bias correction, emotion, and sentiment.

The news media responded to Dr. Oz’s claims by providing more coverage of the ingredient, adding higher sentiment, and failing to correct the bias in his hyped language. “A troubling and noteworthy aspect is that news articles from reputable sources act as an amplifier rather than a rectifier of the original information,” the researchers note. Dr. Oz’s endorsements did not change the intensity of coverage on other channels, but they had a “significant negative effect” on bias correction in reviews and discussions. Consumer sentiment regarding the ingredients improved.

Using search engine data for garcinia cambogia, green coffee beans, raspberry ketones, and other ingredients endorsed in The Dr. Oz Show, the writers also found that consumer interest in the ingredients mentioned rose, a factor mirrored in greater supply. “The number of products with the ingredient increased from almost zero to several hundred listings on Amazon,” they note.

The researchers conclude that consumers can be misled by online health information, adding that “effective regulation of these OTC products––and, more importantly, endorsements––remains the most effective near-term prescription.” They call for greater scrutiny, “not only for OTC products but also––and more critically––for the sources that amplify the benefits and raise the specter of damage to health.”