A New Perspective on Minimally Processed Foods and Diet Quality
A recent study has brought new insights into the ongoing debate about the health benefits of minimally processed foods. Conducted by a team of researchers at the USDA-ARS Grand Forks Human Nutrition Research Center and led by Dr. Julie Hess, this study challenges the notion that eating primarily minimally processed foods, as defined by the NOVA classification system, automatically leads to a healthier diet. The findings suggest that the types of foods we consume may have a greater impact on our health than the level of processing involved.
Comparing Western Diets: Minimally Processed vs. Ultra-Processed
The research compared two menus representative of a typical Western diet. One menu emphasized minimally processed foods, while the other focused on ultra-processed foods, both categorized according to the NOVA classification system. Surprisingly, the less processed menu was found to be more than twice as expensive and had a shelf life three times shorter than the ultra-processed menu, without offering any additional nutritional benefits.
“This study indicates that it is possible to eat a low-quality diet even when choosing mostly minimally processed foods,” said Dr. Julie Hess. “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.”
Dr. Mark Messina, Director of Nutrition Science and Research at Soy Nutrition Institute Global, will present these findings at NUTRITION 2024, the flagship annual meeting of the American Society for Nutrition, held from June 29 to July 2 in Chicago.
Exploring the Possibility of a Low-Quality Diet from Simple Foods
Building on a previous study that demonstrated the possibility of creating a high-quality menu from ultra-processed foods, the new research aimed to determine if it was possible to construct a low-quality menu primarily from minimally processed foods. The researchers developed two menus: a less-processed menu, deriving 20% of its calories from ultra-processed foods, and a more-processed menu, with 67% of its calories from ultra-processed foods. The level of processing for each menu was assessed using the NOVA classification system.
Both menus received a Healthy Eating Index (HEI) score of approximately 43-44 out of 100, indicating poor adherence to the Dietary Guidelines for Americans. The cost of the less-processed menu was estimated at $34.87 per day per person, compared to $13.53 per day for the more-processed menu. Additionally, the median expiration time for the less-processed menu items was 35 days, whereas the more-processed menu items had a median expiration time of 120 days.
Reevaluating the Connection Between Food Processing and Nutritional Value
The study highlights a significant disconnect between food processing and nutritional value. Dr. Hess pointed out that some nutrient-dense packaged foods, such as unsweetened applesauce, ultrafiltered milk, liquid egg whites, and certain brands of raisins and canned tomatoes, can be classified as ultra-processed according to the NOVA system.
“The results of this study indicate that building a nutritious diet involves more than a consideration of food processing as defined by NOVA. The concepts of ‘ultra-processed’ foods and ‘less-processed’ foods need to be better characterized by the nutrition research community,” emphasized Dr. Hess.
Dr. Messina will present this research on June 30 during the Food Choice, Markets and Policy poster session at McCormick Place. This session will offer an in-depth look at the study’s objectives, methods, and findings.
Objectives
The growing “clean eating” trend advocates for consuming primarily foods with simple ingredients, suggesting that fewer processed foods are essential for a healthy diet. However, research shows that a menu consisting mostly of ultra-processed foods (UPFs) can still meet nutrient and diet quality recommendations outlined in the Dietary Guidelines for Americans. This study aimed to explore whether a diet composed mainly of minimally processed foods could also be of low quality. The objective was to compare the diet quality, shelf stability, and cost of two Western-style menus, one with primarily ultra-processed foods and the other with less processed foods, according to the NOVA classification system.
Methods
The researchers developed a less-processed version of a Western menu (less-processed Western, LPW) to align with the Healthy Eating Index (HEI) score of a previously developed more-processed Western menu (MPW). The level of processing was determined by NOVA categorizations assigned by external graders. The final menus were assessed for nutrient content and HEI scores. Shelf stability was estimated using food storage guidance manuals, and the condition of each food item when purchased (shelf stable, frozen, refrigerated) was used to calculate the days until expiration. Food and menu costs were determined using retail prices from a Midwestern grocery chain in Fall 2023.
Results
The LPW and MPW had similar nutrient densities and HEI scores (44 and 43, respectively). The LPW derived 20% of its calories from ultra-processed foods, while the MPW derived 67% from ultra-processed foods. Both menus had similar proportions of shelf-stable, frozen, and refrigerated foods. Using the Kaplan-Meier survival analysis method, the median time to expiration for LPW menu items was 35 days, compared to 120 days for MPW menu items. The cost per person was $34.87 per day for the LPW and $13.53 per day for the MPW.
Conclusions
The study concluded that both less-processed and more-processed menus can provide low-quality diets. However, the less-processed menu was significantly more expensive and had a shorter shelf life compared to the more-processed menu. These findings suggest that the level of food processing is not a reliable indicator of diet quality, and less processed foods can be more costly and have a shorter shelf life.
Funding Sources
This research was supported by the USDA Agricultural Research Service project grant #3062-51000-057-00D.
This study calls into question the assumption that minimally processed foods are inherently healthier than their ultra-processed counterparts. The findings underscore the need for a more nuanced understanding of food processing and its impact on diet quality, cost, and shelf life. As the discussion around healthy eating continues, it is essential to consider these factors to make informed dietary choices.
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