Shopping for yogurt, bread, and granola bars might seem like a healthy decision. Yogurt appears to be a calcium-boosting choice for kids, whole-grain bread seems better than white bread, and granola bars appear to be a healthier snack compared to chips or gummy bears. While these foods might seem nutritious, a growing number of grocery-store items are what scientists call “ultra-processed.” These include fruit-flavored yogurts loaded with sugars, flavorings, and thickeners like guar and carob bean gum, or packaged bread with ingredients like soy lecithin and monoglycerides.
These industrially formulated products, often high in fats, starches, sugars, and additives, now make up 73% of the US food supply. Research increasingly links ultra-processed foods (UPFs) to numerous health issues, including diabetes, obesity, cancer, and depression. Despite these risks, the average American derives more than 60% of their daily calories from ultra-processed foods—more than any other country in the world.
A New Way of Thinking About Nutrition
The term “ultra-processed foods” first appeared in 2009, when Brazilian nutritionist Carlos Augusto Monteiro published a paper making a bold argument: “The issue is not food, nor nutrients, so much as processing.”
Most food undergoes some level of processing, whether it’s an apple that’s been waxed to shine or milk that’s been pasteurized for safety. Processing itself isn’t inherently bad. Techniques like vitamin enrichment and food preservation (such as canning and fermenting) have made the food supply safer and have helped eliminate hunger by making nutritious, shelf-stable foods available year-round.
However, Monteiro identified a new type of processing that emerged in the 1980s and 90s—ultra-processed foods. These include items like many breakfast cereals, packaged snacks, and sugary beverages, which are industrially formulated to be “edible, palatable, and habit-forming.”
The Problem with Ultra-processed Foods
For years, nutritionists focused on the nutrients in food—potassium and fiber were good, while sugar, salt, and saturated fat were concerning in high amounts. But in the early 2000s, Monteiro and his colleagues at the University of São Paulo noticed rising rates of diet-related diseases like obesity and type 2 diabetes, even though Brazilians were consuming less sugar.
They posited that while consuming large amounts of sugar wasn’t good, there was more to it. Fruits like mangoes and bananas are high in sugar, but no one eats a dozen of them in one sitting. Ultra-processed foods, such as candy bars and packaged cookies, however, make it difficult to stop at just one. Scientists later suggested this might be due to the “food matrix” or the chemical and molecular structure of food. The sugars in whole foods like fruit are packaged alongside dietary fiber and vitamins that make them more recognizable and satisfying to our bodies.
A Growing Body of Evidence
Since Monteiro and his colleagues first defined ultra-processed foods, or UPFs, dozens of researchers have explored their effects on the human body. The most convincing evidence came in 2019 when Kevin Hall, a senior investigator with the National Institute of Diabetes and Digestive and Kidney Diseases, published the first randomized, controlled study on ultra-processed foods.
Over four weeks, 20 healthy adult volunteers ate either an ultra-processed or a minimally processed diet for two weeks and then switched to the other diet. Importantly, the diets were matched nutrient for nutrient—those on the ultra-processed diet consumed just as much sugar, fiber, fat, salt, and carbohydrates as those on the minimally processed diet. Both groups were encouraged to eat as much or as little as they wanted.
By the end of the study, Hall found that participants consumed 500 more calories each day during the ultra-processed diet weeks and gained more weight. This indicated that something about ultra-processed foods left people hungrier and wanting more.
Significant Health Impacts
Since Hall’s study, evidence of the negative health impacts of ultra-processed foods has continued to grow. A 2022 study in the British Medical Journal found that men who consumed a large amount of UPFs had a 29% greater risk of colorectal cancer, findings particularly relevant as the rate of colorectal cancer rises among young adults. At the European Society of Cardiology Congress in Amsterdam in August 2023, research showed a 10% rise in daily UPF intake was linked to a 6% increase in heart disease risk. In September, a Harvard study found that women who consumed the most UPFs were 50% more likely to develop depression than those who ate the least.
Researchers from Deakin University in Australia, Johns Hopkins University, the Sorbonne, and others published an umbrella review earlier this year. They found that UPFs were directly linked to 32 harmful health impacts, including hypertension and anxiety. The review suggests that UPFs are most strongly associated with cardiometabolic diseases, common mental health conditions, and higher mortality rates.
Understanding the Mechanisms
Ultra-processed foods have been a helpful lens for scientists to evaluate the impacts of industrially manufactured products. However, researchers are now distinguishing among types of UPFs. Last year, a Harvard study noted that refined breads, sauces, condiments, artificially and sugar-sweetened beverages, animal-based products, and ready-to-eat meals were most closely linked to a higher risk of developing type 2 diabetes. Another Harvard study found that eating UPFs, particularly artificially sweetened food and beverages, was associated with a higher risk of depression.
Future Research and Policy Implications
As evidence mounts on the adverse effects of UPFs, researchers like Leigh Frame from George Washington University emphasize that stronger data could shape US nutrition policy. However, conducting further randomized controlled trials may become unethical given the known health risks of UPFs. Instead, existing studies could pave the way for changes in dietary guidelines and public health strategies.
While researchers are cautious about recommending any food as completely off-limits, they suggest that focusing on overall dietary patterns is more important than eliminating individual foods. Increasing the consumption of whole, minimally processed foods compared to UPFs is a positive step towards better health.
Conclusion
Ultra-processed foods are a major part of the American diet but come with significant health risks. Understanding what qualifies as ultra-processed and being mindful of food choices can help mitigate these risks. By emphasizing whole, minimally processed foods, individuals can improve their diet quality and overall health.