The UK media recently featured the potential health risks of consuming ultra-processed foods (UPFs). These reports stemmed from two short presentations at the European Society of Cardiology Congress 2023.
Ultra-processed foods, categorized using the NOVA system, include items like carbonated drinks, packaged snacks, and mass-produced bread. They are highly processed and these products make up a substantial portion of the British diet, accounting for more than half of the calories consumed by the average person.
Two studies were presented during this session, sparking media interest:
Study 1, conducted by Yang Qu from the Fourth Military Medical University in China, involved a meta-analysis of 10 studies encompassing over 325,000 individuals. It found that those who consumed the most UPFs had a 24% higher risk of experiencing heart attacks and strokes.
Study 2, led by Anushriya Pant from the University of Sydney, Australia, focused on the impact of UPFs on women's heart health. Over a 15-year period, the study tracked 10,000 Australian women aged 46 to 55. Those with the highest proportion of UPFs in their diets were 39% more likely to develop high blood pressure.
While these findings attracted media attention, a number of important points need to be considered:
- Causation vs. Association: Both studies were population-based and established associations, not causation. The media coverage implied that UPFs directly cause harm, but this is by no means proven.
- Relative vs. Absolute Risk: The risk percentages (24% and 39%) reported in the studies may sound substantial, but the absolute risk remains very low. For example, even if the 39% higher risk mentioned in Study 2 were applied to heart events instead of blood pressure, it would make a difference of a fraction of 1 in 1,000.
- Healthy Person Confounder: Population studies struggle to account for various factors that affect health, such as smoking, sedentary lifestyle, and low income. These confounding variables can make it challenging to attribute health outcomes solely to UPF consumption.
- Lack of Peer Review: The studies presented at the conference have not undergone peer review, raising questions about the robustness of their methodologies and findings.
We've looked at UPFs before in newsletters and the evidence has been poor quite frankly. The relative risks observed in these studies fall well short of the criteria required to even start considering causation. While it's wise to avoid processed foods for overall well-being, claims that consuming processed food is a serious health hazard are not supported by the available data.