Diets rich in minimally processed foods don’t necessarily offer better nutritional benefits than those with more ultra-processed items. A study comparing two Western diets found similar nutritional scores but noted that minimally processed foods were more expensive and had shorter shelf lives.
A new study calls into question the level of processing as a proxy for diet quality.
Recent research challenges the notion that minimally processed foods automatically lead to a healthier diet, revealing that both minimally and ultra-processed diets can be equally nutritious or lacking in nutritional value. The study highlighted that minimally processed diets might be costlier and have shorter shelf lives without additional nutritional benefits, emphasizing the complexity of defining diet quality by processing levels alone.
Dietary Choices and Processing Levels
New research demonstrates that eating primarily minimally processed foods, as they are defined by the NOVA classification system, does not automatically make for a healthy diet. It suggests that the types of foods we eat may matter more than the level of processing used to make them.
Comparing two menus reflecting a typical Western diet — one emphasizing minimally processed foods and the other emphasizing ultra-processed foods, as categorized by the NOVA classification system — the researchers found that the less processed menu was more than twice as expensive and reached its expiration date over three times faster without delivering any additional nutritional value.
Examples of a more-processed (left) and less-processed (right) breakfast. None of the ingredients used to make the less-processed meal are considered ultra-processed (both the bread and jam are homemade), while almost all of the components of the more-processed meal are considered ultra-processed. Credit: Courtesy of USDA-ARS
Research Findings on Processed vs. Minimally Processed Diets
“This study indicates that it is possible to eat a low-quality diet even when choosing mostly minimally processed foods,” said Julie Hess, PhD, a research nutritionist at the USDA-ARS Grand Forks Human Nutrition Research Center, who led the study. “It also shows that more-processed and less-processed diets can be equally nutritious (or non-nutritious), but the more-processed diet may have a longer shelf life and be less costly.”
Mark Messina, PhD, director of nutrition science and research at Soy Nutrition Institute Global, recently presented the findings at NUTRITION 2024, the flagship annual meeting of the American Society for Nutrition.
Evaluating Nutritional Quality Across Different Diets
The new research builds on a study the team published last year, which demonstrated that it was possible to build a high-quality menu that aligns with dietary guidelines while deriving most of its calories from foods classified as ultra-processed. For the new study, the researchers asked the opposite question: Is it possible to build a low-quality menu that derives most of its calories from “simple” foods?
To find out, they constructed a less-processed menu, which derived 20% of its calories from ultra-processed foods, and a more-processed menu, which derived 67% of its calories from ultra-processed foods. The level of processing involved in each menu was determined according to the NOVA system of classification.
The two menus were calculated to have a Healthy Eating Index score of about 43-44 out of 100, a relatively low score that reflects poor adherence to the Dietary Guidelines for Americans. The researchers estimated that the less-processed menu would cost $34.87 per day per person compared with $13.53 per day for the more-processed menu. They also calculated that the median time to expiration of the less-processed menu items was 35 days versus 120 days for the more-processed menu items.
The study draws attention to the disconnects between food processing and nutritional value. Hess noted that some nutrient-dense packaged foods can be classified as ultra-processed, such as unsweetened applesauce, ultrafiltered milk, liquid egg whites and some brands of raisins and canned tomatoes.
“The results of this study indicate that building a nutritious diet involves more than a consideration of food processing as defined by NOVA,” said Hess. “The concepts of ‘ultra-processed’ foods and ‘less-processed’ foods need to be better characterized by the nutrition research community.”
Unprocessed, but SAD: A Standard American Diet Made With Less-Processed Foods Is Still a Standard American Diet
Presenting Authors:
Julie M. Hess, PhD, USDA-ARS Grand Forks Human Nutrition Research Center
Mark Messina, PhD, MS, Director of Nutrition Science and Research, Soy Nutrition Institute Global
Co-Authors:
Madeline E. Comeau, MS, USDA-ARS Grand Forks Human Nutrition Research Center
Angela J. Scheett, USDA-ARS Grand Forks Human Nutrition Research Center; University of North Dakota
AnneBodensteiner, Ph.D., RDN, LRD, University of North Dakota
Allen S. Levine, University of Minnesota, United States
Daniel Palmer, USDA-ARS Grand Forks Human Nutrition Research Center
The “clean eating” trend of consuming primarily foods with simple ingredients suggests that consuming fewer processed foods is a requisite aspect of healthy dietary patterns. Yet research indicates that a menucontaining mostly ultra-processed foods (UPFs) can meet nutrient and diet quality recommendations from the Dietary Guidelines for Americans. Whether a diet comprised mostly of simple ingredient foods can provide a low-quality diet remains unexplored. The objective of this study was to compare the diet quality, shelf stability, and cost of two similar Western-style menus, one containing primarily energy from UPFs and the other containing primarily energy from less processed foods, as defined by the Nova food classification system.
First, a less-processed version of a Western menu (less-processed Western, LPW; more-processed Western MPW) with a Healthy Eating Index (HEI) score of approximately 43 was developed to align with the HEI score of the previously developed MPW. Processing level was determined by Nova categorizations assigned by external graders. The final menu was assessed for nutrient content and HEI score. Shelf stability of foods was determined with information from food storage guidance manuals. The condition of each fooditem when purchased (shelf stable, frozen, refrigerated) was used to estimate the number of days until expiration. Food and menu costs were determined using retail prices at a Midwestern grocery chain in Fall 2023.
The LPW and MPW had similar nutrient densities and HEI scores (44 and 43, respectively). The LPW included 20% energy (kcal) from UPFs, while the MPW included 67% energy from UPFs. Relative percentages of shelf-stable, frozen, and refrigerated foods were similar between the two. Using the Kaplan-Meier survival analysis method, median time to expiration of the LPW menu items was 35 days versus 120 days for the MPW menu items. The “per person” cost was $34.87/day for the LPW and $13.53/day for the MPW.
The less-processed and more-processed menusboth provided low-quality diets. However, the LPW was more than twice as expensive as the MPW and had a shorter overall shelf life. Level of processing is not a proxy indicator of diet quality, and less processed foods can be more expensive and have a shorter shelf life.
Funding: USDA Agricultural Research Service project grant #3062-51000-057-00D
It is an interesting study however, it’s worth to note that the study was comparing the USA LPW and MPW products whilst even if the NOVA system of classification has been used still I am sure the method of processing is different in different countries in western world.