This week the BMJ published a study with the title ‘’Consumption of ultra-processed foods and cancer risk”
You may have seen the study or at least parts of it which have been cherry-picked to make the headlines. Sadly, most articles in the media failed to highlight the flaws in the study which has left people feeling slightly confused and terrified around food.
What were the results?
A 10% increase in the proportion of ultra-processed foods in the diet was associated with a significant increased of greater than 10% in risks overall and breast cancer”
The biggest red flag question for me is how did they define “Ultra-processed food”? Essentially it is a huge and very vague category including foods prepared by a variety of methods containing various nutrients and additives. The definition is rather arbitrary with little scientific basis – for example, mass-produced bread is included by artisan bread is excluded.
The researchers used data from a large cohort study that tracks the eating habits and health of thousands of French people. People were included in the current study if they had been part of the cohort for two to six years. Their dietary intake on joining the study was assumed to have been their standard eating pattern for life. I know that my diet now is certainly not the same as it was in my 20s – and I suspect that’s true for most people.
Thirdly, it is an observational study (not our gold standard) and so all confounders or variables can’t really be excluded. The authors also found that smoking and low physical activity were more common in those who consumed the greatest proportion of processed foods. Also we can only infer association not causality from an observational study.
Where do we go from here?
Cancer is a complex, multifactorial disease caused by the interaction between genes and the environment. A single study does not prove anything and it certainly does not show that any foods cause cancer. It does suggest that there may be a link between processed food and cancer – but whether it is directly from the food, or indirectly from lifestyle factors or low SES is not clear. I know journalists have to earn a living too but sensationalist headlines and documentaries lead to scare-mongering around food (example: What the health documentary) *eye roll*
Cook when you can and focus your diet around fruit and vegetables, whole grains, legumes, nuts + seeds, +/- meat/fish/dairy and consume packaged or processed foods as and when you need to.
Reduce the booze