From sugary cereal to many burgers, supermarkets nowadays are chock full of ultraprocessed foods. In fact, in countries like the US or the UK, ultraprocessed foods make up to 50% of the calories people eat. By now, hopefully, it should be clear to everyone that this type of food is usually (if not always) unhealthy. But here’s the thing: it’s not just the poor nutritional quality of the foods — something else is wrong.

It’s not hard to understand why ultraprocessed foods are appealing. It’s not just the fact that they’re easy to buy and palatable, often without having to cook — but these are essentially foods custom-made for the human taste. They’re sweet or meaty or whatever because we like that type of food. But there’s a few problems with that.

For starters, the processing these foods undergo strips away many of the nutritional benefits of foods. A large part of the fiber, vitamins, and minerals in these products is destroyed through processing. That alone is enough to warrant staying clear of ultraprocessed foods, but there’s more to it.

Two recent studies, one carried out in Italy and the other in the US looked at the effect of ultraprocessed food on health. The first study tracked over 20,000 healthy Italian adults and unsurprisingly found that participants who consumed the most ultraprocessed foods had an increased risk of dying prematurely from any cause. The second study, which looked at over 50,000 US male health professionals, found that higher consumption of ultraprocessed foods is linked with a greater risk of colon cancer.

So far, nothing really surprising. But these effects persisted even after the poor nutritional quality was accounted for. So what gives?

Ultra-bad

These studies suggest that there’s something else in ultraprocessed foods that is bad for you. In other words, even if you’d get your vitamins and fibers from someplace else, or if ultraprocessed foods would be artificially fortified with nutrients, they’d still be bad.

A key clue may come from the Italian study. The study found that people who consumed more ultraprocessed foods had more markers of inflammation. Inflammation is a common process in our body, it happens when you catch a cold or when you get hurt in whatever way. Normally, it comes and goes away quickly. Ultraprocessed foods often contain products like emulsifiers that can trigger inflammation in the body, and if you eat a lot of ultraprocessed food, then the inflammation may remain constant.

Chronic inflammation has been linked to conditions ranging from diabetes and heart problems to dementia and cancer — it’s particularly linked to a higher risk of colon cancer. While the US study did not clarify whether there was an inflammation link, it seems plausible. At any rate, ultraprocessed foods seem to cause inflammation in the body, and this inflammation can be very problematic in the long run.

There are other potential explanations. Some studies have found a link between ultraprocessed foods and impaired kidney function. Toxins in food packaging or other additives in the food themselves can cause mild adverse reactions — but these reactions, over a long period of time, can make you more prone to disease.

Of course, giving up on ultraprocessed food is not an easy thing to do. After all, it’s made in a way that makes it specifically appealing to our taste, and many of these foods are pretty addictive and convenient to purchase. We’re also constantly bombarded by clever and aggressive marketing.

Recognizing ultraprocessed foods can also be tough. It’s not like it’s specifically mentioned on the packaging (though that could be a good idea), and the best way to see how much a product is processed is to check the nutritional facts label. Products with many ingredients, and especially ingredients like emulsifiers, flavorings, and artificial sweeteners, are a good hint that the food is heavily processed.

If you want to eat healthier without adhering to a diet, the best thing to do is to eat things that have been cooked from scratch in the last 24 hours. Look for plant-rich foods, foods low in saturated fats, and foods that contain fiber. Your body will thank you for it.