Dr. Chris van Tulleken is an infectious diseases doctor at UCLH, one of the BBC's leading science presenters, and a New York Times bestselling author.

In 2023, Chris published "Ultra Processed People," an exposé on the food industry, which became an international bestseller.

In the summer of 2021, Chris and Xand launched their first podcast, "A Thorough Examination with Drs Chris and Xand," which reached the top spot across a variety of podcast charts. The audio series follows Chris sending Xand on a journey to explore his relationship with ultra-processed food. Xand meets the world's leading experts on food, weight, taste, and addiction while going on a UPF binge in a bid to see if he can learn to hate it. Series 2 was launched in 2022 and focused on whether people can change and how they do it.

In 2019, Chris, alongside his twin brother Xand, put competing health theories to the test with the help of 30 other pairs of identical twins in 'Twinsitute' for BBC Two. The pair also hosted 'Planet Child,' a 'landmark perspective on global childhood development,' for ITV.

Chris' concerns about antibiotic resistance and over-reliance on prescription drugs led him to create a campaigning series for BBC One in 2017 called 'The Dr Who Gave up Drugs,' which generated a huge volume of letters and emails, striking a chord with the nation. In 2018, he turned the focus of the topic to children with the second series, which received rave reviews.

Following the success of 'The Doctor Who Gave Up Drugs,' Chris investigated the impact ultra-processed foods have on our children in 'What Are We Feeding Our Kids?' for BBC One.

Another highlight of 2017 was Chris' BBC1 film "The Truth About...HIV," a program supported by HRH Prince Harry and Sir Elton John.

"Operation Ouch," Chris and Xand's double BAFTA & Broadcast award-winning series for CBBC, continues to delight audiences around the world, with Series 12 being filmed in 2023. Throughout the series, the twins create fun and often disgusting experiments to help kids learn how the human body works.

Chris and Xand's programs are often shaped by their readiness and ability to self-experiment and test out theories on one another (as clones, they are the ideal test and control). Whether changing their diets, exposing themselves to environmental extremes of heat, cold, sleeplessness, or pain (sticking spikes through their faces and sticking cameras down their noses), Chris learns and informs his audience by becoming a patient himself.

Chris and Xand grew up in London and trained in medicine at Oxford University, specializing in infectious disease and tropical medicine.