A new study puts a great deal of doubt on the level of processing as a stand-in for diet quality.
One of the commonly held views that a diet comprising only minimally processed foods automatically translates to a healthy diet was dented in a new study, showing that both minimally and ultra-processed diets are similarly either equally or poorly nutritional. Such findings make the case for the minimally processed diet most likely more expensive with a short shelf life, devoid of any added nutritional benefits, showing just how troublesome it is to define diet quality based on the levels of processing alone.
Dietary Choices by Levels of Processing
It’s an idea now fleshed out by a new study, in which the meat is really put onto the bones: a diet based on mainly minimally processed foods is not per se healthful as defined by the NOVA classification system. This research now proves what is really eaten, not how it is processed.
A Western diet represented by two menus, the first based on minimally processed foods and another based on ultra-processed foods, using the NOVA system of classification for foods, scientists found that the menu with fewer processes was more than twice as expensive, its expiration date more than three times sooner, and did not bring added nutritional value.
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 with the USDA-ARS Grand Forks Human Nutrition Research Center, who led the study. “It also shows more 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.”
The results were presented recently at NUTRITION 2024, the flagship annual meeting of the American Society for Nutrition, by Mark Messina, PhD, director of nutrition science and research at Soy Nutrition Institute Global.
Assessment of Nutritional Quality of Diets
The new study builds on a previous one from the same team last year, in which researchers showed it’s possible to create a high-quality menu that adheres to dietary guidelines and yet gets most of its calories from foods classified as ultra-processed. In the new study, the researchers turned the question on its head: Is it possible to create a low-quality menu that gets most of its calories from “simple” foods?
They then prepared one less-processed menu that got 20% of the calories from ultra-processed foods, and another menu that was more processed, with 67% coming from ultra-processed foods. Processing levels in the menus were defined according to the NOVA system.
The two menus had an estimated Healthy Eating Index score of about 43-44 out of 100-a low score that reflects poor adherence to the Dietary Guidelines for Americans. The less-processed menu cost about $34.87 per person per day, based on nutritional data from the researchers. The more-processed menu had a per person, per day cost of approximately $13.53. Besides, the median time to expiration of the less-processed menu items was estimated to be 35 days, against the more-processed menu items, whose estimated median time to expiration is 120 days.
Level of processing is often quite removed from nutritional quality, one takeaway from the study. Hess said some healthful packaged foods can fit into the ultra-processed category, including unsweetened applesauce, ultra-filtered milk, liquid egg whites and some brands of raisins and canned tomatoes.
“The results of this study demonstrate that constructing a healthful diet entails much more than a consideration of food processing as defined by NOVA,” said Hess. “The constructs of ‘ultra-processed’ foods and ‘less-processed’ foods require more thorough characterization 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
This “clean eating” pattern, which predominantly is an intake of few-ingredient foods, has generally helped to drive home the perception that lower consumption of processed foods is requisite for healthful dietary patterns. Recent evidence suggests, however, that a menu swamped with ultra-processed foods can meet nutrient recommendations and diet quality from the Dietary Guidelines for Americans. What is not clear is whether a low-quality diet can be provided by a diet composed mostly of simple ingredient foods. This study aimed to compare diet quality, shelf-stability, and cost of two similar Western-style menus—one with a majority of energy from UPFs and one with a majority from less processed foods—based on Nova, the food classification system.
First, a less processed version of the Western menu-less processed Western, LPW; more processed Western MPW-was developed to match the previously developed MPW’s HEI score about 43. The processing level was determined by use of Nova categorizations assigned by external graders. The last menu was analyzed for nutrient content and HEI score. The shelf stability of foods was determined using information from food storage guidance manuals. Number of days until expiration was estimated based upon the condition of each food item at time of purchase (shelf stable, frozen, refrigerated). Food and menu costs were calculated utilizing retail prices at a Midwestern grocery chain prices in Fall 2023.
Nutrient densities and HEI scores were similar for the LPW and MPW at 44 and 43, respectively. The LPW consisted of 20% energy from UPFs, and the MPW consisted of 67% of energy from UPFs. By relative percentages, there were close representations of shelf-stable, frozen, and refrigerated foods in both. Median time to expiration of menu items using Kaplan-Meier survival analysis method was 35 days for LPW menu items and 120 days for MPW menu items. The “per person” cost was $34.87/d for the LPW and $13.53/d for the MPW.
Both the less and more-processed menus provided low-quality diets. The LPW, however, was more than twice as expensive as the MPW and had a shorter overall shelf life. Level of processing is not a proxy indicator for 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
Source: https://scitechdaily.com/
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