Nutrient content more important than degree of processing

“Ultra-processed foods” — they have become buzz words. But new research from a team of U.S. and Brazilian academics suggests that nutrient content is more important than the degree to which the foods we eat have been processed.

Liu et al.¹ found that the consumption of ultra-processed foods (UPFs) is highly correlated with diet quality, that is, the higher the intake of UPFs, the lower the quality of the diet. This finding suggests the association between UPF intake and adverse health outcomes results from poor diet quality, rather than because there is something inherently unhealthy about certain foods simply because of the processing they have undergone.² Since soy-based meat and soymilk qualify as UPFs, according to the definition used by Liu et al.¹  their finding suggests these foods should be judged on their nutritional merits, and not on the extent to which they have undergone processing.

The study population used by Liu et al.¹ was the two most recent analyses (2015−2016 and 2017−2018) of the National Health and Nutrition Examination Survey. Investigators separately evaluated children (aged 2−19 years, n= 5,919) and adults (aged ≥20 years, n= 10,064). Dietary habits were assessed through 1−2 standardized 24-hour dietary recalls per person. UPFs were defined as industrial formulations manufactured from substances derived from foods with little, if any, whole food and typically with added flavors, colors, and other additives.³

Diet quality was assessed using American Heart Association (AHA) diet score and the Healthy Eating Index (HEI)-2015 score. The 5 primary dietary components of the AHA diet score are total fruits/vegetables, whole grains, fish/shellfish, sugar-sweetened beverages (SSBs), and sodium. The AHA secondary dietary components add nuts/seeds/legumes, processed meat, and saturated fat. The HEI-2015 reflects adherence to key recommendations in the U.S. Dietary Guidelines for Americans. The 9 adequacy components include total fruit, whole fruit, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood and plant protein, and fatty acids. The 4 moderation components include refined grains, sodium, percentage of energy from added sugars, and percentage of energy from saturated fatty acids.

Compared with the lowest quintile of UPF consumption in children (<50.2% energy), the multivariable-adjusted score for the highest quintile (>79.0% energy) was -6.22 lower for the AHA primary score and -9.96 lower for the AHA secondary score. Among adults, compared with the lowest quintile of UPF consumption (<39.1% energy), the diet score for the highest quintile (>70.7% energy) was -7.24 lower for the primary AHA and -12.6 lower for the secondary AHA score. Similar results were found for HEI-2015 scores among both children and adults.

These findings align with those from Juul et al.⁴ who analyzed U.S. grocery purchasing data from the National Household Food Acquisition and Purchase Survey 2012−2013. They observed that households purchasing the most UPFs (>67.9% energy) scored 10.7 points lower on the HEI-2015 than those purchasing the least (<48.4% energy) and were furthest from meeting the 2015−2020 Dietary Guidelines for Americans for total fruits, whole fruits, total vegetables, greens and beans, total protein food, seafood and plant protein, refined grains, sodium, and added sugars, excluding only whole grains.

As noted at the onset, soy-based meat and most soymilks are classified as UPFs. Soy-based meats qualify as UPFs because they are typically made using concentrated sources of soy protein such as soy protein isolate or soy protein concentrate, which are comprised of ≥90% and 65-90% protein, respectively.⁵ Even soymilks made from whole soybeans qualify because of the added sugar and emulsifiers they typically contain.⁶ Since dietary guidelines increasingly recommend limiting the intake of UPFs, consumers may choose to avoid these soy-based meat and dairy products. However, in the opinion of this author, the findings from Liu et al.¹ and Juul et al.⁴ emphasize the importance of judging foods on their nutritional merits, not on the extent to which they have been processed.

When this approach is adopted, soyfoods are nutritionally competitive with other protein products.⁷ The plant-based meat products are made using high-quality soy protein⁸ which has been shown to modestly lower blood cholesterol levels⁹ and in the 2020 U.S. Dietary Guidelines, fortified soymilk was determined to be the only plant milk nutritionally similar to cow’s milk.¹⁰

References

1. Liu J, Steele EM, Li Y, Karageorgou D, Micha R, Monteiro CA, Mozaffarian D. Consumption of ultraprocessed foods and diet quality among U.S. children and adults. Am J Prev Med 2021.
2. Lane MM, Davis JA, Beattie S, Gomez-Donoso C, Loughman A, O’Neil A, Jacka F, Berk M, Page R, Marx W, et al. Ultraprocessed food and chronic noncommunicable diseases: A systematic review and meta-analysis of 43 observational studies. Obesity reviews : an official journal of the International Association for the Study of Obesity 2021;22:e13146.
3. Monteiro CA, Cannon G, Levy RB, Moubarac JC, Louzada ML, Rauber F, Khandpur N, Cediel G, Neri D, Martinez-Steele E, et al. Ultra-processed foods: what they are and how to identify them. Public health nutrition 2019;22:936-41.
4. Juul F, Simoes BDS, Litvak J, Martinez-Steele E, Deierlein A, Vadiveloo M, Parekh N. Processing level and diet quality of the US grocery cart: is there an association? Public health nutrition 2019;22:2357-66.
5. Codex General Standard for Soy Protein Products, Codex Standard 175-1989. 1989.
6. Drewnowski A. Perspective: Identifying ultra-processed plant-based milk alternatives in the USDA Branded Food Products Database. Adv Nutr 2021.
7. Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Science 2018;360:987-92.
8. Hughes GJ, Ryan DJ, Mukherjea R, Schasteen CS. Protein digestibility-corrected amino acid scores (PDCAAS) for soy protein isolates and concentrate: Criteria for evaluation. J Agric Food Chemistry 2011;59:12707-12.
9. Jenkins DJA, Blanco Mejia S, Chiavaroli L, Viguiliouk E, Li SS, Kendall CWC, Vuksan V, Sievenpiper JL. Cumulative meta-analysis of the soy effect over time. Journal of the American Heart Association 2019;8:e012458.
10. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov. 

 This blog is sponsored by SNI Global and the United Soybean Board.