When you open a bag of nacho-flavoured chips or cheese puffs, you probably know that you鈥檙e about to indulge in an unhealthy snack.
The dead giveaway? It鈥檚 the yummy, spicy, cheesy, neon-orange dust that coats each morsel and gets all over your fingers. Ditto for a frozen pizza and chicken nuggets.
But what about a granola bar? An applesauce pouch? String cheese? Flavoured yogurt? Surely these foods 鈥 snacks that millions of children and adults eat every day 鈥 are not bad, right?
Well, it turns out that many fall under the category of ultraprocessed foods 鈥 depending on their exact ingredients. This type of food has been studied a lot lately, and the results aren鈥檛 great.
Ultraprocessed foods represent a relatively new way of categorizing foods. Proposed in 2009 by researchers at the University of São Paulo in Brazil, the system, called , is based not on what kind of food it is 鈥 meat, grains, vegetables, etc. 鈥 but rather on how processed it is.
NOVA separates foods into four groups, starting with natural and minimally processed foods in the first category to , which use industrial formulations and manufacturing techniques, in the fourth.
鈥淢y operating definition for ultraprocessed (foods) is you can鈥檛 make it in your home kitchen because you don鈥檛 have the machinery and you don鈥檛 have the ingredients,鈥 food policy expert Dr. Marion Nestle told CNN Medical Correspondent Meg Tirrell on the Chasing Life podcast recently. Nestle is the Paulette Goddard Professor of nutrition, food studies and public health, emerita, at New York University.
Ultraprocessed foods contain additives such as flavour enhancers, colours and thickeners 鈥 basically ingredients you wouldn鈥檛 usually use in your cooking. It makes them shelf-stable, easy to prepare (just heat and serve) and in many cases hard to resist. (The food industry pushes back on the NOVA system, saying there is no agreed-upon scientific consensus on the definition of ultraprocessed.)
Due to a confluence of historical, regulatory and economic factors, Nestle said, food companies in the 1980s 鈥渄id a lot of work on trying to figure out what flavour and texture and colour combinations would be most attractive to people and started producing foods that would make them lots of money.鈥
She said tens of thousands of new products have hit store shelves since then. 鈥淢ost of them fail, but the ones that win, win big,鈥 Nestle said.
Before you reach for that can of soda, bag of chips or frozen dinner, why not learn more about what you鈥檙e eating? Here are five things to know about ultraprocessed foods:
Ultraprocessed foods are linked to bad health outcomes
Eating a lot of ultraprocessed foods isn鈥檛 healthy.
鈥淣ow there have been more than 1,500 observational studies 鈥 all of them demonstrating a consistent finding, which is that eating ultraprocessed foods is linked to obesity, type 2 diabetes, heart disease, certain cancers, bad outcome from COVID-19, overall mortality,鈥 Nestle said. 鈥淎ny bad health problem you can think of that鈥檚 related to diet is related specifically to ultraprocessed foods.鈥
The most recent study, published Wednesday in The BMJ journal, analyzed more than 30 years鈥 worth of data and found that eating ultraprocessed foods was associated with a 4% higher by any cause, including a 9% increased risk of neurodegenerative deaths. Other studies have linked ultraprocessed foods to heart disease, Type 2 diabetes, cancer and mental health disorders such as anxiety and depression.
Nestle pointed out that these studies have been observational and not designed to prove causation 鈥 that ultraprocessed foods caused these bad health outcomes.
鈥淵ou can do that when you have a controlled clinical trial,鈥 she said. 鈥淎nd guess what? We have one.鈥
Ultraprocessed foods cause weight gain
That one randomized, controlled clinical trial showed that ultraprocessed foods actually caused people to .
These types of studies are not easy or cheap to undertake, which is why they are not done more often. To conduct this one, Dr. Kevin Hall, a senior investigator at the National Institute of Diabetes and Digestive and Kidney Diseases, had 20 volunteers spend four weeks living at the National Institutes of Health Clinical Center in Bethesda, Maryland.
For two weeks, they ate a diet made up of 80% healthy ultraprocessed foods (think yogurt and whole wheat bread, not chips and soda). For the other two weeks, they ate a diet that contained no ultraprocessed foods. The diets were matched, among other things, for calories, sugar, fat, fibre and macronutrients. Participants did not know what exactly the study was measuring.
鈥淲e basically just asked people, you know, just eat as much or as little of the food that you鈥檇 like,鈥 Hall told Tirrell. 鈥淵ou shouldn鈥檛 be trying to change your weight, (you) shouldn鈥檛 be trying to gain weight or lose weight. Just eat to the same level of appetite as you normally would.鈥
Researchers found that when the participants were on the ultraprocessed diet, they ate about 500 calories more per day than when they were on the minimally processed one. This difference in calories translated quickly to the scale. Participants gained on average 2 pounds during the two weeks on the ultraprocessed diet and lost 2 pounds on the minimally processed one. And their blood work showed lower markers of inflammation when they were on the latter.
鈥淚f you鈥檙e not familiar with nutrition research, you have no idea what an important finding this is,鈥 said Nestle, who was not involved in the study. 鈥淔ive hundred calories is huge.鈥
Hall said it鈥檚 unclear what drives people to consume more calories when they are on an ultraprocessed diet. 鈥淥ne of the things that we鈥檙e really interested in now,鈥 he said, 鈥渋s to figure out what the mechanisms were.鈥
Ultraprocessed foods are hard to avoid
Ultraprocessed foods are everywhere, and most of us consume them without even realizing it 鈥 even when you think you are eating something relatively healthy, such as baked potato chips or a peanut butter and jelly sandwich.
Using data from the National Health and Nutrition Examination Survey, researchers found that ultraprocessed foods make up more than half of American adults鈥 diets. For U.S. children, that percentage is even higher, at 67%.
Ultraprocessed foods are cheap and convenient
Yup, that鈥檚 right: Truly eating 鈥渃lean鈥 costs more.
鈥淭o actually create the minimally processed menu, it was about 40% more expensive than the ultraprocessed menu,鈥 Hall said. 鈥淭hat doesn鈥檛 even account for the time that it takes to make the foods, right? So, all those factors probably play a huge role in 鈥 the foods that we choose to eat in the real world.鈥
Not all ultraprocessed foods are bad
Some ultraprocessed foods can provide important nutrients, such as whole wheat bread and yogurt. And others, in Hall鈥檚 study, were shown not to increase caloric intake.
鈥淭he snacks were neutral in terms of how many calories (the participants) ate,鈥 Hall said. 鈥淲hich goes to show that not all ultraprocessed foods necessarily drive this effect.鈥
Hall鈥檚 team is conducting a new study to tease out which ultraprocessed foods are harmful and which are neutral, or even healthy.
Americans may soon get more help sorting through the health effects of ultraprocessed foods. The US Department of Agriculture and the US Food and Drug Administration will soon issue new Dietary Guidelines, which are updated every five years. Nestle said that the scientific advisory committee guiding this process has been asked to consider the connection between ultraprocessed foods and poor health outcomes.
