January 2024
HOW EATING ULTRA-PROCESSED FOODS CAN AFFECT YOUR HEALTH
Recent studies link diets high in these foods to increased risk of obesity, cancer and other ailments.
Should granola come with a warning label? Concern is rising about the amount of ultra-processed foods in American diets, and the effect eating so many of these foods has on our health. Part of the problem is that many healthy-seeming foods (breakfast cereals, soups and yogurts as well as granola) fall into this category. Recent studies have linked diets high in ultra-processed foods to increased risk of obesity, type 2 diabetes, cancer, cardiovascular disease and depression. Yet there is no set definition of what makes a food ultra-processed, and scientists are still figuring out exactly why eating these foods is associated with health problems. These foods are coming under a microscope as the U.S. government prepares the latest version of its dietary guidelines. For the first time, the government is asking its scientific advisory committee to consider how diets consisting of varying amounts of ultra-processed foods influence body composition and disease risk. Food companies dispute the idea that their products are unhealthy and say that packaged food gives people a convenient, affordable way to get nutrition. Ultra-processed foods now make up a majority of Americans’ diets. About 58% of the calories adults and children ages 1 and older consume in a day come from ultra-processed foods. Among children the number is higher and growing. Frozen pizza, chicken nuggets and protein bars, the bulk of them ultra-processed, are popular for a reason: They are cheap, tasty, and convenient.
What is the definition of an ultra-processed food? Nutrition researchers generally consider foods ultra-processed if they include ingredients you wouldn’t find in a home kitchen, such as high-fructose corn syrup, corn syrup and emulsifiers. Many researchers define foods’ level of processing using a classification system published by scientists in Brazil. Unprocessed or minimally-processed foods are close to their natural state: fruits, vegetables, plain meat. They might be altered via processes such as drying, roasting, or pasteurizing but they lack added salt, sugar, or other food substances. Processed foods might be preserved by canning, bottling or some fermentation, and might contain ingredients such as butter or salt: Think canned beans, cheese, or fresh bread you would find at a local bakery. Most ultra-processed foods have some engineering involved. To make them, companies generally break down whole foods and chemically modify them to create ingredients like soy protein and maltodextrin, a sweetener derived from corn, or other grains. Ultra-processed foods also often include ingredients that enhance a food’s flavor, color or texture.
What’s healthy? Not all ultra-processed foods are equal, and some might be good for you. Plenty of foods that tout health benefits with labels like “organic” or “a good source of whole grains” or “low in sugar” are ultra-processed. The more of those you see on a product, the more likely it is to be ultra-processed. Eggs or milk or plain fruit and vegetables don’t carry claims.
The health risks. In nature, most foods are either high in fat, like meat, or high in carbohydrates, (which all turn to sugar, or glucose, in the body), like fruit. Ultra-processed foods are often high in both fat and carbohydrates, which causes them to act more potently on the reward systems in our brains and can make them addictive. Foods such as ultra-processed ice cream, French fries, pizza, and chips are beyond anything our brains evolved to handle. Diets high in fat, sugar and sodium are associated with cardiovascular disease and other health issues. An NIH study found that people who ate a diet high in ultra-processed foods consumed more calories and gained weight compared to people who ate a minimally processed diet, even though the diets contained roughly the same amounts of calories, fat, sugar, sodium, and fiber. Scientists created two diets, one with most calories coming from foods like packaged muffins and deli turkey and the other with most calories coming from minimally processed foods, including scrambled eggs and salads with chicken. When people ate the majority-ultra-processed diet, they ended up consuming about 500 calories more than they did on the less-processed diet. After 2 weeks, they gained about 2 pounds. Participants lost about 2 pounds after 2 weeks on the unprocessed diet. People eating ultra-processed foods had to consume more calories to attain the same level of satisfaction and fullness as they did on the other diet.
One way ultra-processed foods may contribute to weight gain is that they often contain more calories per gram compared with less-processed foods. This is because when companies make ultra-processed products, they break down the cellular structure of the raw ingredients and remove the water. Highly processing foods make them more rapidly digestible, so that few calories and nutrients make it to your large intestine, which can change the microbiome in the gut. Because the microbiome digests calories, this means that even if two people are eating the same number of calories, the one consuming lots of ultra-processed foods will have more calories available to be turned into fat compared with someone eating a largely minimally processed diet. You can imagine how difficult it is for the first person to keep the weight off.
What to do. To reduce the amount of ultra-processed foods in your diet, choose whole foods as often as you can. Frozen vegetables, canned beans, canned tuna, and roasted nuts can be convenient and quick. With packaged foods, health claims like “low in sugar” or “heart healthy” are often a giveaway that they are ultra-processed. When looking at labels, choose items with fewer ingredients overall and try to avoid those with ingredients you don’t recognize. And you can add unprocessed foods to ultra-processed foods to make them healthier. Toss fresh broccoli into boxed macaroni and cheese or add plain vegetables to a frozen meal.
How ultra-processed foods affect the body:
Brain: Foods high in both refined carbohydrate and fat (which many ultra-processed foods are) enhance activity in the reward systems in the brain, likely making them more addictive.
Mouth: When people eat ultra-processed foods, they consume more calories per minute. During processing, water is often removed from the ingredients, making the product more energy dense.
Liver: The rapid rush of glucose, fructose and amino acids from ultra-processed foods can overwhelm the liver and create visceral fat around the organs, which can result in fatty liver disease.
Small intestine: A diet high in ultra-processed foods can change the gut microbiome. Imbalances in the gut microbiome have been linked to obesity and type 2 diabetes.
Small intestine: Many ultra-processed foods are rapidly digested, starting in the mouth and then almost completely digested in the stomach and small intestine.
Andrea Petersen
Sources: Ashley Gearhardt, the University of Michigan; Kevin D. Hall, National Institutes of Health; Darlush Mozaffarian, Tufts University; Cleveland Clinic. Jemal Brinson/The Wall Street Journal