The cocktail of additives and preservatives in upf harm people in ways both known and unknown.
It seems to affect the gut microbiome, the trillions of bacteria that contribute to health in a range of ways.
Calorie-rich but usually nutrient-poor, upf contributes to obesity in part because its palatability and soft texture foster overconsumption, overriding satiety signals from the brain.
Because this frankenfood is cheap to produce and buy, upf displaces healthier alternatives, particularly for poor people.
Extra weight was once a sign of wealth, but among British and American women today, obesity rates are higher at lower-income levels.
(Curiously, rates do not vary for men, even though a greater share of American men than women are obese.)
The reasons why upf can be harmful are not always clear, even to scientists.
Additives that may be safe in isolation or small quantities may be harmful in combination with other chemicals or when consumed regularly.
If we are what we eat, considering the impact of upf is essential, but too often Mr van Tulleken’s case for clean food is accompanied by anti-capitalist preening: for instance, he nonsensically calls corporate-tax minimisation “part of ultra-processing”.
Environment matters, too.
People who live in what the author calls “food swamps”, where “upf is everywhere but real food is harder to reach”, could spend large amounts of time and money seeking out fresh food, but that is not how most people live.
There is nothing wrong with the odd fast-food trip, but anyone who can afford to eat less upf probably should.