The debate over ultraprocessed foods: Should they be incorporated in dietary guidelines?

Research has shown that ultraprocessed foods are associated with weight gain and an increased risk for chronic conditions.

However, there is debate whether unprocessed or minimally processed foods should be recommended over ultraprocessed foods in dietary guidelines.

Two papers published in The American Journal of Clinical Nutrition explored this debate, with both authors offering counterarguments and rebuttals.

Carlos A. Monteiro, MD, PhD, a professor of nutrition and public health at the University of Sao Paulo, and Arne V. Astrup, MD, PhD, the program director of Novo Nordisk Foundation in Copenhagen, answered the question, “Does the concept of ultraprocessed foods help inform dietary guidelines beyond conventional classification systems?” with Monteiro responding “yes” and Astrup “no.” They will present their cases on June 14 in a live debate during the American Society for Nutrition’s annual meeting.

Monteiro and colleagues created the NOVA system, which is used to classify foods by their degree of industrial processing. Classifications range from unprocessed to ultraprocessed.

NOVA defines ultraprocessed foods — like candy, packaged snacks, soft drinks and ready-to-heat products — as foods that are “made using sequences of processes that extract substances from foods and alter them with chemicals or additives in order to formulate the final product,” according to a press release from the American Society for Nutrition.

But according to Astrup, the NOVA classification “adds little to existing nutrient profiling systems; characterizes several healthy, nutrient-dense foods as unhealthy; and is counterproductive to solve the major global food production challenges.”

Astrup pointed out that meals made from similar ingredients by the same processes might be classified differently based on where they are prepared. For example, the ingredients to make a pizza are the same, but if preparation is industrial, then it is considered an ultraprocessed food.

“The Nova classification of ultraprocessed foods ... rests on poorly defined food processes and the presence of food additives from a chemically heterogeneous group, easily leading to misclassification,” Astrup wrote.

Despite Astrup’s concerns, the recommendation to eat mostly fresh meals instead of ultraprocessed foods, following the NOVA food classification system, “is being increasingly adopted in new official dietary guidelines issued by national governments and international health associations,” Montiero wrote.

“This recommendation is supported by systematic reviews and meta-analyses of nationally representative dietary surveys and long-term cohort studies. These data show that increased intake of ultraprocessed foods is associated with poor-quality diets and with increased morbidity and mortality from several chronic diseases,” Monteiro wrote.

Monteiro cited studies that show the negative effects of ultraprocessed food, such as an increased risk of chronic diseases and weight gain, and wrote that guidelines should “make explicit the need to avoid ultra-processed foods.”

“Various attributes of ultraprocessed foods acting through known, plausible, or suggested physiologic and behavioral mechanisms relate them to ill health, and it is likely that different combinations of attributes and mechanisms affect different health outcomes,” Monteiro wrote. “Although more research should be done to identify these mechanisms, existing evidence is sufficient to recommend the avoidance of ultraprocessed foods to optimize health and policies to support and make feasible this recommendation.”

Astrup recognized that ultraprocessed foods “are claimed to promote overconsumption of energy and obesity due to high palatability,” but said that “little evidence supports effects beyond those that can be accounted for by nutrient composition, energy density, and food matrices.” He additionally stated that studies involving ultraprocessed foods “are especially susceptible to confounding,” which is “the bias resulting from the presence of factors associated with both exposures and outcomes.”

Astrup also wrote that observational studies link obesity to ultraprocessed foods, but none so far “have demonstrated independent associations after controlling for likely confounders,” referencing a controlled feeding study that compared a diet of ultraprocessed foods with an unprocessed diet.

The study, Astrup wrote, “showed a rapidly weaning effect on energy intake that can be entirely explained by more conventional and quantifiable dietary factors, including energy density, intrinsic fiber, glycemic load, and added sugar.”

“Clearly, many aspects of food processing can affect health outcomes, but conflating them into the notion of ultraprocessing is unnecessary, because the main determinants of chronic disease risk are already captured by existing nutrient profiling systems,” Astrup wrote.

References:

• Are ultra-processed foods harmful? Experts weigh the evidence. https://www.eurekalert.org/news-releases/954892. Published June 7, 2022. Accessed June 7, 2022.
• Astrup A, Monteiro CA. Great debates in nutrition: Does the concept of ‘ultra-processed foods’ help inform dietary guidelines, beyond conventional classification systems? Presented at: American Society of Nutrition Scientific Sessions and Annual Meeting; June 14-16, 2022 (virtual meeting).
• Monteiro CA, Astrup A. Am J Clin Nutr. 2022;doi.org/10.1093/ajcn/nqac122.
• Monteiro CA, Astrup A. Am J Clin Nutr. 2022;doi.org/10.1093/ajcn/nqac123.