[Column] Misunderstandings about ultra-processed foods

Are ultra-processed foods the ultimate culprit for health issues? If recent health-related news is any indication, they might be. A study, published in The Lancet in September 2024 by researchers from the Harvard T.H. Chan School of Public Health, followed over 200,000 American adults for 30 years. The findings revealed that individuals consuming the most ultra-processed foods faced an 11 percent higher risk of cardiovascular disease and a 16 percent higher risk of coronary artery disease compared to those who consumed the least.

However, the study has two notable limitations. First, it relies on self-reported dietary surveys, which are often imprecise since most people struggle to recall their exact food intake. Second, as an observational study, it cannot establish causation—meaning it’s unclear whether ultra-processed foods directly increase cardiovascular risk or if other factors are at play.

Adding to the complexity, the definition of ultra-processed foods is far from clear-cut. In 2009, researchers at Universidade de São Paulo in Brazil introduced the Nova classification system, which categorizes foods into four levels of processing. Group 1 includes minimally processed or unprocessed foods, while Group 2 consists of processed culinary ingredients like sugar and salt. Group 3 covers processed foods, and Group 4 encompasses ultra-processed foods. The distinction often hinges on the number of additives: foods with fewer additives are classified as processed, whereas those with more are considered ultra-processed. For example, sweetening plain yogurt with sugar or jam turns it into an ultra-processed food. Similarly, tofu can fall into either the processed or ultra-processed category, depending on the additives used. Even home-cooked meals blur the lines—making stew from scratch is considered unprocessed, but adding seasoning elevates it to ultra-processed status.

However, little scientific evidence suggests that adding small amounts of flavoring significantly changes a food's properties or health effects. For instance, adding sugar or flavoring doesn’t necessarily turn yogurt into an unhealthy food. In fact, the Harvard study mentioned earlier found that certain ultra-processed foods—such as sweetened yogurt, frozen yogurt, ice cream, cereal, popcorn, and crackers—were associated with a reduced risk of cardiovascular disease. Among the 10 ultra-processed food categories analyzed, only two were linked to an increased risk: sugary drinks and processed meat, poultry, and fish. These findings align with the conventional wisdom that excessive consumption of sugar and processed meats can harm health.

The real issue with ultra-processed foods lies in their appeal: they’re delicious, affordable, and convenient, making it easy to overconsume them. A 2019 study by the U.S. National Institutes of Health highlighted this problem. In the study, 20 participants consumed about 500 more calories per day when following an ultra-processed diet compared to a minimally processed one. Over two weeks on the ultra-processed diet, participants gained 0.9 kg, while they lost the same amount during two weeks on the minimally processed diet. These findings suggest that quantity matters more to your health than whether a food is processed. The takeaway? Eat less.

Jeong Jae-hoon is a food writer and pharmacist. He covers a variety of subjects, including trends in food, wellness and medications. This column was originally published in Korean in Joongang Ilbo on Dec. 5, 2024. – Ed.