Skeptics with a K

Episode #453

February 26, 2026

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  • The central discussion in this segment of Skeptics with a K, Episode #453, critically examines recent media reports linking ultra-processed foods (UPFs) to rising early-onset bowel cancer by analyzing the underlying study, which actually found a correlation between high UPF intake and the presence of conventional adenomas (benign polyps) in a specific cohort of US nurses. 
  • The hosts express significant skepticism regarding the media's sensationalized reporting, arguing that the term 'may' is misused to imply causation where only correlation exists, especially given the vague and inconsistent definition of UPFs (using the NOVA classification) and the study's reliance on self-reported dietary data from a non-diverse cohort. 
  • The episode highlights that the incidence of bowel cancer in those under 50 has increased by 62% since the early 1990s (from 7.4 to 11.7 cases per 100,000), but stresses that this increase is from a very small baseline number, and the study specifically found a link only to polyps, most of which are benign and do not develop into cancer. 

Segments

Sponsor Reads and Intro
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(00:00:00)
  • Key Takeaway: Aura offers comprehensive digital protection including VPN, antivirus, and identity theft insurance, while Instacart allows users to specify grocery preferences like banana ripeness.
  • Summary: Data brokers are highlighted as selling personal information, prompting the introduction of Aura as a service that removes data and offers security features. Instacart is promoted for its new preference picker feature allowing users to dictate specific ripeness levels for produce like bananas. The podcast officially begins by stating the date and its dedication to science and critical thinking.
Host Voice Recording Issues
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(00:01:35)
  • Key Takeaway: One host lost their voice after spending six hours shouting into a microphone to pre-record nine or ten episodes of Skeptics with a K.
  • Summary: A host explains their current croaky voice is due to an extreme effort to pre-record a large volume of voice-overs for future episodes. This marathon recording session lasted six hours, resulting in vocal strain that will affect their voice for several upcoming episodes. The hosts also briefly mention the difficulty of reading very long articles for voice-over segments.
UPF and Bowel Cancer Study
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(00:04:25)
  • Key Takeaway: Media headlines link UPFs to rising bowel cancer in under-50s based on a study showing a correlation with conventional adenomas (polyps) in US nurses.
  • Summary: News headlines from The Guardian, Good Housekeeping, and The Mirror suggest UPFs are linked to increased risk of bowel cancer precursors in younger individuals. The study analyzed data from the Nurses Health Study 2, focusing on early-onset colorectal neoplasia (abnormal cell growth). The authors noted the incidence of early-onset colorectal cancer is increasing globally in parallel with UPF consumption, though the role remains unexplored.
Critique of UPF Definition
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(00:13:06)
  • Key Takeaway: The NOVA classification defines UPFs by the presence of ingredients rarely used in culinary settings, such as high-fructose corn syrup and protein isolates, alongside industrial processing techniques.
  • Summary: The NOVA classification categorizes UPFs as industrially manufactured products containing specific additives and food substances with ’no or rare culinary use.’ These substances include various sugars, modified starches, and protein isolates. The inclusion of factors like sophisticated packaging and emphatic branding in the definition complicates isolating specific physiological causes of health effects.
Study Methodology and Findings
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(00:20:00)
  • Key Takeaway: The study found that participants in the highest quintile of UPF intake had a higher risk of developing conventional adenomas, but not serrated lesions, after adjusting for numerous confounding factors.
  • Summary: Researchers reviewed pathology reports from 29,105 nurses who had undergone endoscopies before age 50, blinding reviewers to dietary data. High UPF intake correlated with factors like higher BMI, lower physical activity, and less screening endoscopy use. The key finding was an increased risk for conventional adenomas, but not serrated lesions, when comparing the highest versus lowest UPF consumption groups.
Media Reporting Critique
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(00:30:09)
  • Key Takeaway: The primary issue with the reporting is the use of the word ‘may’ to imply causation between UPFs and cancer risk, when the study only showed correlation with usually benign polyps in a specific demographic.
  • Summary: The actual finding is that American women reporting high UPF intake had more growths in the bowel that are generally benign and take years to potentially become cancerous. Banning the word ‘may’ in science journalism is advocated because it allows reporters to imply causation without scientific backing, leading to fear-mongering and health anxiety. Specific, measurable advice, like that given for processed meat intake, is needed rather than broad categories like UPFs.
Personal Updates and Events
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(00:35:14)
  • Key Takeaway: One host saw a production of Tom Stoppard’s Arcadia at the Old Vic, which was staged ‘in the round,’ while another host is preparing a talk for the sold-out State of the Browser conference in London.
  • Summary: The production of Arcadia was praised for its staging in the round, effectively handling the play’s dual timelines set in 1809 and the present day. The play itself explores themes of historical uncertainty and entropy, which one host found appealing due to their interest in history and science tensions. Upcoming events include the Liverpool Skeptics in the Pub social on March 5th and a Mega Mix event two weeks later at Fredericks.