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Research Feature: Using less processed food does not improve nutrient value, cost, or shelf life
7 October 2024
There is an assumption that consuming fewer processed foods and adopting a “clean eating” approach is key to a healthy diet. While packaged and processed food can be nutrient-dense, the inverse of this statement can also be true i.e. less-processed and “clean label” foods can be nutrient-poor.
A recent US study (1) compared the diet quality, shelf stability, and cost of two similar nutrient-poor menus based on a Western-style diet, one containing primarily ultra-processed foods and the other containing less processed foods, as defined by the Nova classification system.
Nutrient quality:
The study found that using less-processed foods to mimic a standard American diet of 2000 cal (8400 kJ) does not improve nutrient value. Both the Less-Processed Western (LPW) and More-Processed Western (MPW) menus had similar nutrient density and diet quality scores (Healthy Eating Index scores of 44 and 43 out of 100, respectively). While both the LPW and an adjusted Less-Processed Western (aLPW) generally provided more energy, protein, fat, calcium, magnesium, potassium, and vitamin D compared to the MPW, the MPW provided more iron and vitamin C.
Note, an adjusted Less-Processed Western (aLPW) menu was created to address the issue that more items on the original LPW were categorised as ‘ultra-processed foods’ (Nova Category 4) than anticipated.
Cost:
The LPW menu was more expensive than the MPW menu. The “per person” cost was $15.91/day for the LPW compared to $9.85/day for the MPW. This indicates that less-processed foods can be more costly.
Shelf life:
The aLPW and LPW menu had a shorter shelf life compared to the MPW menu as they had a higher percentage of refrigerated foods and a lower percentage of shelf-stable and frozen foods. The median time to expiration for LPW items was 35 days, whereas it was 120 days for MPW items. This suggests that more-processed foods have better shelf stability.
Diet quality and processing level:
The study concluded that the level of food processing, as defined by the Nova classification system, does not serve as a proxy indicator of diet quality. Both less-processed and more-processed menus can have comparable diet quality scores. The LPW was developed to match the meals and recipes in the MPW using less-processed ingredients. Less-processed versions of the foods on the MPW were identified from grocery retailer websites based on their ingredient lists. For example, chocolate milk was replaced with white milk, and canned beans in the chili recipe were replaced with dry beans prepared in a slow cooker.
Consumer implications:
Encouraging consumers to decrease intake of processed foods does not guarantee that they will select more nutritious options. The study highlights that more-processed foods can provide accessible, nutrient-dense options and may lead to decreased food waste due to their longer shelf life.
These points collectively suggest that while less-processed foods are often perceived as healthier, they may not necessarily offer better nutrient quality, can be more expensive, and have a shorter shelf life compared to more-processed foods.
While this study is the first at examining this concept of less processed foods being less healthy, it does have some limitations such as the challenge of identifying foods by level of processing, especially using the Nova classification system, and that cost data had limited applicability as it was sourced at a local grocery chain during a period of inflation.
Reference
- J.M. Hess, M.E. Comeau, A.J. Scheett, A. Bodensteiner, A.S. Levine, using less processed food to mimic a standard American diet (SAD) does not improve nutrient value and May result in a shorter shelf life at a higher financial cost, Current Developments in Nutrition, https://doi.org/10.1016/j.cdnut.2024.104471.
