How bad is ultra-processed food, and what does it do to you?
Eating a lot of ultra-processed food is consistently associated with higher risks of cardiovascular disease, diabetes, depression and premature death. The evidence is observational and not always of high quality, but the associations are broad enough to make limiting intake a sensible choice.
People who eat a lot of ultra-processed food have a 21% higher chance of dying from any cause, and a 50% higher chance of dying from cardiovascular disease. Those are substantial numbers, although the underlying studies vary in quality and the findings reflect associations, not proven causal relationships.
The strongest finding concerns type 2 diabetes: both a dose-response relationship and a direct risk analysis point in the same direction. Eating more ultra-processed food is associated with a 12% higher risk per step up in consumption, and with a 40% higher risk in a separate analysis. This is the only outcome in the entire analysis rated as having 'moderate' evidence quality, which makes it relatively well supported. Obesity follows a similar pattern: a 55% higher chance, including in children.
Particularly striking are the associations with mental health. People who eat a lot of ultra-processed food have a 48% higher chance of anxiety complaints and a 44% higher chance of depressive symptoms. In addition, follow-up studies show that they are also more likely to develop depression later on. That goes beyond a snapshot in time, but a direct cause has not yet been established. Most studies in this area are cross-sectional, so caution in interpretation is warranted.
For cancer, the figures are worrying but the evidence is more limited. A 10 percentage point higher share of ultra-processed food in the diet is associated with 13% more cancer overall, 30% more colorectal cancer and 49% more pancreatic cancer. Much of this cancer research looks back in time, which makes it less reliable. No association was found for prostate cancer.
Exactly how ultra-processed food causes harm has not yet been fully clarified. Three mechanisms are being investigated: it displaces more nutritious products, it has an unfavourable profile of salt, sugar and fat, and the industrial processing itself, with additives such as emulsifiers and sweeteners, appears capable of damaging the gut microbiome and gut wall. That last point has so far been observed mainly in laboratory and animal research, and has not been robustly demonstrated in humans.
All claims are based on observational studies and meta-analyses (PMID 38418082, 35807749, 37866398, 37087831, 38388570, 35658669, 36542406). Causal relationships have not been proven for most outcomes. GRADE quality ranges from 'low' to 'moderate'.
How much does ultra-processed food increase your risk of dying?
A high intake of ultra-processed food is associated with a higher risk of dying, but estimates vary widely (2% to 21%) and cause and effect has not been established. The greatest reduction in risk comes from improving your overall diet and limiting processed meat products.
Are ultra-processed products bad for your longevity?
Eating a lot of ultra-processed products is associated with a shorter lifespan and more chronic disease, but the effect varies considerably by product type and largely disappears when your overall diet is good. Eating less processed meat and improving your overall eating pattern gives you the greatest benefit.
How much sugar is too much?
There is no universal threshold, but for tooth decay, getting less than 10% of your daily calories from free sugars is the evidence-based guideline. Sugar-sweetened drinks deserve the most attention: they raise the risk of diabetes more clearly than sugar from solid food.
Are diet soft drinks and sweeteners bad for you, and if so, why?
Studies where people were assigned to a sweetener or comparison drink show that diet soft drinks at moderate consumption are not demonstrably more harmful than water, and are probably more favourable than sugary soft drinks when you swap one for the other. Open questions remain about gut bacteria, so drinking less soft drink overall remains the most defensible goal.
Does eating spicy food help you live longer?
Eating spicy food regularly is linked to a lower chance of dying early, but whether it is the cause is not yet known. With stomach cancer, a little may be beneficial while a lot could actually be harmful, so moderation is key.
Is eating organic food really healthier?
Eating organic probably does not give you better nutritional value, but it does lower your exposure to pesticide residues and to antibiotic-resistant bacteria via meat. For pregnant women and young children, that is the most concrete and well-supported argument.