Heart disease, cancer, diabetes — these and other concerning health effects have been tied to "ultraprocessed foods," which make up more than half of the calories consumed in the U.S. Eating large amounts of these foods, which are high in salt, sugars and additives, may even increase a person's risk of early death.
There's growing awareness around the potential harms of these products, but which foods count as "ultraprocessed" is not always clear.
So what, exactly, are ultraprocessed foods?
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Define 'ultraprocessed'
Almost all foods are processed in some way, but classification systems distinguish the types of processing they undergo. One commonly used system is the NOVA classification system, which categorizes food into four groups, Adrian Brown, a senior research fellow at University College London, told Live Science in an email. These include unprocessed and minimally processed foods, processed culinary ingredients, processed foods and ultraprocessed foods.
Unprocessed foods include the edible parts of plants or parts from animals as they're found in nature — for example, fresh, whole heads of broccoli; unsalted seeds; mushrooms; and eggs. Minimally processed foods are slightly altered to make them more suitable or safe to consume, meaning they may be frozen, roasted or dried. Nothing is added to these foods, so they're free of salt, sugar or oil. Examples include frozen peas and roasted coffee beans.
Next you have processed culinary ingredients, used to season and cook foods and obtained by slightly processing foods from the first group. For instance, vegetable oils can be derived from crushed seeds.
Processed foods include smoked meats, canned vegetables, tofu and fresh breads. They contain multiple ingredients and increase a food's shelf life, generally by adding processed culinary ingredients, like salt. They're still considered versions of the original foods — for instance, packaged applesauce is made from whole apples.
Ultraprocessing, on the other hand, dramatically transforms ingredients through intensive, industrial methods.
NOVA defines ultraprocessed foods as "formulations of ingredients, mostly of exclusive industrial use, typically created by series of industrial techniques and processes." Examples of ingredients used only in industrial settings include specific sugars, such as dextrose, and protein sources, such as casein.
Ultraprocessing involves breaking down foods into their component parts, such as starches and oils. These are then chemically modified — to break bonds between their molecules, for instance — and combined with techniques like extrusion, which forces soft substances together into a desired shape. Colors, flavors, emulsifiers and other additives are also used to enhance a food's taste and shelf life.
Ultraprocessed foods include soft drinks, candies, breakfast cereals, chicken nuggets, hot dogs and instant soup powders. They are meant to be convenient to prepare and tasty to consume.
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Dangers of ultraprocessed foods
There are several reasons ultraprocessed foods are bad to eat in excess, Dr. Jennifer Hankenson, who practices physical medicine and rehabilitation at Yale Medicine, told Live Science in an email.
"One is because they have additives that are dangerous to our health and increase the risk of developing chronic health conditions such as diabetes, cancer, heart disease, and high blood pressure," Hankenson told Live Science. Ultraprocessed foods often have an excess of certain ingredients, such as sugar and salt, that make them highly palatable, making it harder for consumers to stop eating at suggested serving sizes, she said.
The products are also low in fiber, so they're absorbed quickly in the gastrointestinal tract and don't adequately nourish the gut microbiome. In addition, evidence suggests they don't set off the same satiety signals as unprocessed foods do, leaving people feeling hungrier.
Hankenson said eating small amounts of ultraprocessed foods likely isn't bad for you. However, she noted that no amount would be considered "healthy" or "recommended," per se, especially for people with chronic health conditions.
Erikka Loftfield, an investigator at the National Cancer Institute, said the organization recently conducted a study of more than 500,000 people that linked high ultraprocessed-food intake to a higher risk of all-cause mortality. The research, which has yet to be published, also found a link to death caused by either heart disease or diabetes.
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Ultraprocessed meats and soft drinks were the products most strongly associated with mortality risk, Loftfield told Live Science in an email.
Importantly, though, "there are a wide range of foods and beverages classified as ultraprocessed foods according to the NOVA system, and it is unclear how each of these foods impacts human health," Loftfield noted.
Brown added that, although these classifications can be helpful, it may sometimes be tricky to tell if a food is ultraprocessed. Food labels, such as those that say "all natural," can be deceptive and are not regulated by the Food and Drug Administration.
If you're interested in getting professional help to better navigate food choices, a dietitian or nutritionist may be able to guide you toward the healthiest choices for you.
This article is for informational purposes only and is not meant to offer medical advice.
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