By Densie Webb, PhD, RD
Vol. 25 No. 4 P. 30
A Primer on What They Are and Their Potential Health Effects
The term “processed foods” tends to have a negative connotation among many consumers and reducing the intake of processed foods is often high on the to-do list of those trying to improve their diets. But processed foods exist on a continuum and can be divided into different categories depending on the degree to which a food has been processed. However, foods that fall into the ultraprocessed category are what consumers need to be most concerned about.
According to Robert H. Lustig, MD, a professor of pediatrics in the division of endocrinology and director of the Weight Assessment for Teen and Child Health Program at the University of California at San Francisco, “Most people can’t immediately distinguish between ‘food’ and ‘ultraprocessed food [UPF].’” Yet, that distinction is more important than ever. According to a recent study on the topic, the global food system has undergone a “profound transformation” in terms of technology and food processing and has significantly shifted in favor of highly processed foods for convenience, competition, and consumer appeal.1
What Exactly Is a UPF?
According to Amy Kimberlain, RDN, LDN, CDCES, a spokesperson for the Academy of Nutrition and Dietetics, “In recent years there has been more awareness brought to this very topic; however, I think there is still quite a bit of misunderstanding and misuse of the term and what constitutes a ‘processed’ food, let alone an ‘ultraprocessed food.’”
The USDA defines a processed food as any food that has undergone any change from its natural state, including washing, cleaning, milling, cutting, chopping, heating, pasteurizing, blanching, cooking, canning, freezing, drying, dehydrating, mixing, or packaging.2 This definition encompasses almost every food consumers purchase. Prepackaged green beans, Brussels sprouts, or broccoli, with no additives or preservatives, are considered to be minimally processed. Processed foods are products in which oil, sugar, or salt are added before being packaged, like canned corn, tuna, or beans. UPFs are foods that go through multiple processes such as extrusion, molding, or milling; contain many added ingredients and few nutrients; and are high in sugar, fat, and/or sodium. The list is long, but foods that fall into the ultraprocessed category include soft drinks, chips, candy, ice cream, sweetened breakfast cereals, packaged soups, rice mixes, chicken nuggets, hot dogs, and french fries.3
UPFs are further defined by a classification system called NOVA (not an acronym), which assigns food to one of four groups based on the extent and purpose of industrial processing.4 NOVA was developed in 2009 by a group of Brazilian researchers to better categorize the level of processing among food products. The NOVA classification system is important because it’s the one most researched on UPFs to identify the diets of populations.5 But the classification system isn’t without controversy. Some critics have labeled the NOVA classification system as ambiguous at best and invalid at worst.6 The NOVA classification system doesn’t include any references to the nutrient content of foods, and critics say this classification system labels 60% of the American food supply as “unhealthy” and ultraprocessed, including foods many dietitians may consider nutritious, such as some high-fiber breakfast cereals, infant formulas, canned pasta sauce, soymilk, and plant-based burgers.7 Moreover, some foods conceivably could fall into more than one category, making a clear classification difficult.
NOVA separates different levels of processed foods into four groups: 1) Unprocessed or minimally processed foods (MPFs) that include edible parts of plants, animals, or fungi without any processes applied to them or natural foods altered by minimal processing designed to preserve natural foods to make them suitable for storage, or make them safe, edible, or more palatable; 2) Processed culinary ingredients, which are substances extracted from MPFs, not intended for consumption on their own; 3) Processed foods, which are industrial products made by adding processed culinary ingredients to MPFs, such as canned vegetables in brine, fruit in syrup, and cheese; and 4) UPFs are defined as a formulation of ingredients, mostly of exclusive industrial use, that result from a series of industrial processes, many requiring sophisticated equipment and technology, such as sweet and savory snacks, reconstituted meats, pizza dishes, and confectionary. Ingredients characteristic of UPFs include food substances that make the final product more palatable, such as sugar, protein, oil derivatives (eg, high-fructose corn syrup, maltodextrin, protein isolates, hydrogenated oil), and cosmetic additives (eg, colors, flavor, flavor enhancers, emulsifiers, thickeners, and artificial sweeteners).4
Michael Pollan, author of several books on healthful eating, including In Defense of Food, makes a simple recommendation for limiting overly processed foods—avoid any food that has more than five ingredients, or to simplify even further, he has said, “Don’t eat anything your great grandmother wouldn’t recognize as food.” That may be an oversimplification, but the NOVA system may be overcomplicated.
Increased Consumption of UPFs
Despite their negative reputation among many consumers, UPFs have become dominant components in the diets of populations worldwide—contributing more than 50% of energy intake in high-income countries and up to 30% in middle-income countries—and consumption is rapidly increasing.4 Using data from NHANES 2009–2010, researchers, who used the NOVA classification, found that UPFs comprised 57.9% of energy intake in the United States and contributed almost 90% of energy intake from added sugars. The amount of added sugars in UPFs was eightfold higher than in processed foods. Only those Americans in the lowest quintile of UPF consumption met the recommended limit of less than 10% of calories from added sugars.8
The rate of increased consumption of UPFs appears to be a significant issue among young people. Based on NHANES data from 1999 to 2018, the estimated proportion of energy intake from consumption of UPFs increased among youth aged 2 to 19 from 61.4% to 67% during that time period,9 while the percentage of energy intake from unprocessed food or MPF decreased from 28.8% to 23.5%. Lustig, who’s also the chief science officer of the nonprofit Eat Real, says the organization is working to reverse the trend by helping school districts alter their fast food–focused business model to incorporate real food for K–12 students.
Cost and convenience are major factors steering consumers to UPFs. Lustig says it’s important to acknowledge that UPFs are cheaper because of food subsidies. “These distort the market,” he says. “If we got rid of subsidies for corn, wheat, soy, and sugar, the price of ‘real food’ would decline to meet the cost of UPFs.”
Health Effects of UPFs
There are plenty of epidemiologic studies demonstrating an association between consuming a diet high in foods classified as ultraprocessed and poor health. “Virtually every study demonstrates a correlation between the degree of ultraprocessed food consumption and the prevalence of diabetes, heart disease, dementia, cancer, as well as all-cause mortality, and these correlations are independent of calories and obesity,” Lustig says.
A systematic review and meta-analysis of 43 observational studies found that consumption of UPFs was associated with increased risk of overweight, obesity, abdominal obesity, all-cause mortality, metabolic syndrome, cancer, and irritable bowel syndrome, among other health conditions.10 Another recent systematic review and meta-analysis of 23 observational studies found that increased UPF consumption was associated in a limited number of the studies with a worse cardiometabolic risk profile and a higher risk of CVD, depression, and all-cause mortality.1
A recent analysis of data obtained from the Health Professionals Follow-Up Study, the Nurses’ Health Study, and the Nurses’ Health Study II found that high consumption of UPFs was associated with an increased risk of colorectal cancer, the third most commonly diagnosed malignancy among men and women in the United States and the second leading cause of death from cancer worldwide.11
Dementia is another concern. One study of more than 72,000 participants from the UK Biobank Study, aged 55 and older, who were free of dementia at the start of the study were followed for a median of 10 years. The researchers found that higher consumption of UPF was associated with higher risk of dementia. In modeling, they found that replacing just 10% of UPF in the diet with an equivalent proportion of unprocessed or MPFs was estimated to be associated with a 19% lower risk of dementia.12 A similar finding resulted from a cohort study of 10,775 individuals in Brazil aged 35 to 74. After a median follow-up of eight years, the researchers found that a higher percentage of daily energy consumption of UPFs was associated with cognitive decline.13
An additional concern associated with UPF consumption was highlighted in a recent study published in the Journal of the Academy of Nutrition and Dietetics.14 The study provided preliminary support for an association between household food insecurity and addiction to highly processed foods by the activation of neural reward responses due to UPFs’ hyperpalatability. The researchers analyzed data from two earlier studies, the Maternal Adiposity, Metabolism and Stress study and the Family Food Study, which evaluated families in California and Michigan. The researchers concluded that despite data being collected in different geographic regions, time periods, and stages of parenthood, a similarity existed in the link between food insecurity leading to a higher intake of highly processed foods and food addiction.
Moreover, a greater risk of death has been associated with a high intake of UPFs. A recent prospective cohort study involving more than 44,000 French adults found that for each 10% increase in UPFs in the diet, a 14% higher risk of death during the seven-year study was observed, even when other lifestyle factors such as smoking and exercise were factored in.15
While there are more than enough epidemiologic studies to suggest an association between consumption of UPFs and poor health—even death—clinical studies are rare because of the time it would take to observe an effect of the diet. However, the National Institutes of Health conducted a 28-day controlled study in which 10 healthy men and women stayed at the NIH Clinical Center and consumed either an ultraprocessed or minimally processed diet for two weeks. While both diets had the same number of calories, sugars, fiber, fat, and carbohydrates, participants could eat as much or as little as they wanted.16 The researchers found that people who consumed the diet high in UPFs had a higher calorie intake (about 500 kcal more per day) and gained weight (about 2 lbs). Although consumption of high-calorie UPFs has been associated with overweight and obesity in this and other studies, Lustig says, “Studies show that UPFs cause weight gain beyond its calorie equivalence.” He points to three possible reasons: a) mitochondrial dysfunction [leading to metabolic changes], b) inflammation and insulin resistance, and c) lack of satiety leading to continued consumption.
Because such a large portion of the American diet consists of UPFs, counseling clients and patients on reducing intake can be challenging. “At the heart of my counseling,” Kimerlain says, “is to meet patients where they are and begin to make small changes in order to improve health.” She says a detailed dietary history is key to get a better understanding of what they’re eating (eg, Is “chicken,” chicken from the meat department, chicken that’s frozen and preserved, or chicken in a can?). But, she says, she doesn’t go in depth with the terms “processed” and “ultraprocessed” with clients. She suggests asking, “what is one thing you can do today that would improve your health? They may have a list of things they’d like to change or work on; however, starting slow and implementing these changes one at a time and that they can stick with over time is what’s most important.”
— Densie Webb, PhD, RD, is a freelance writer, editor, and industry consultant based in Austin, Texas.
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