While a diet of cakes and doughnuts is clearly not optimal, it might surprise you to hear that processed foods are not always unhealthy.
There has been a lot of fervour in the media lately around the concept of ultra-processed foods (UPFs) and their effects on health. This is because diets high in UPFs have been associated with a greater risk of death and chronic conditions like type 2 diabetes (1,2). However, not all UPFs may be similarly bad for health. In fact, whole grain breads, fruit-based products and yoghurts were examples of UPFs that were associated with a lower risk of type 2 diabetes in one of these prior studies, whereas white breads, sugary drinks, and animal-based products were associated with a greater risk (Figure 1) (2).
What I am touching upon is that just because a food is processed, that doesn’t automatically mean it’s bad for you. In fact, some processed foods may be good for you. Before we go any further, perhaps we should get an idea of what constitutes a ‘processed food'.
Figure 1. This study found that while UPFs were associated with increased risk of type 2 diabetes, some UPFs were associated with a lower risk, highlighting the fact that not all UPFs seem to be similarly detrimental to health (2).
What Are Processed Foods?
There are a number of food classification systems that group foods by how processed they are, the most well-known of which being the NOVA classification (3). NOVA classes foods into four distinct categories (4):
Group 1: Unprocessed or minimally processed foods
These are foods in their natural state (e.g., fruits, vegetables, meat, eggs) or slightly altered by processes (e.g., drying, roasting, boiling, freezing)
Group 2: Processed culinary ingredients
These are ingredients that are derived from Group 1 foods or from nature that are used to prepare or season foods (e.g., oils, butter, sugar, salt)
Group 3: Processed foods
These are foods that are made by adding Group 2 foods to Group 1 foods and most have only two or three ingredients (e.g., homemade bread, canned fish/beans in vinegar or salted water)
Group 4: Ultra-processed foods
These are ‘formulations made mostly or entirely from substances derived from foods and additives, with little if any intact Group 1 food' (e.g., sugary drinks, sweet or savoury packaged snacks). This group can also include foods that have just one unnatural additive (e.g., a stabiliser to keep the product shelf-stable or a sweetener) but otherwise would be Group 3 foods (e.g., certain yoghurts, industrial [including whole grain] breads) (5)
Source: studyfinds.org
Not All Processed Foods Are Bad
It is pretty clear that Group 3 (processed) foods are not necessarily bad for health. Take a loaf of homemade whole grain bread, for example. We know that whole grains are a very healthy food group; evidence shows that higher vs. lower intakes of whole grains is associated with a significant reduction in risk of cardiovascular disease, type 2 diabetes, cancer, and death from any cause (6,7). This is the same story for canned fish and beans, which are examples of healthy food groups that are associated with a lower risk of chronic diseases (8,9).
What about UPFs? While I am absolutely not saying that cookies, cakes, doughnuts, etc. are healthy foods (they’re not), there are some foods that NOVA classifies as Group 4 ‘Ultra-processed foods’ that are healthy. For example, calcium-set tofu and most brands of soy milk are classified as UPFs according to NOVA (10), but greater consumption of these foods has been associated with significant reductions in risk of death from any cause (11). Similarly, yoghurts and whole grain breads would be classified as an UPF according to NOVA if they contain any unnatural additives, but yoghurt consumption is associated with a small (but significant) reduction in cardiovascular disease risk (12), and we have already mentioned the health benefits associated with eating whole grains (6,7).
A meal with tofu, an example of a healthy UPF. Source: lifemadesweeter.com
Summary
Hopefully you now have a more nuanced appreciation of this topic. What I don’t want you to take away from this article is that UPFs are all fine to eat—there is good evidence to suggest that a diet high in UPFs is associated with a greater risk of chronic disease and premature death. So no, cookies, crisps, fizzy drinks, etc. are not healthy foods. However, what I do hope you take from this article is that just because a food is processed (or ultra-processed), this is not sufficient to tell us whether it is healthy or not. In other words, there are likely other factors highly prevalent in these unhealthy UPFs (e.g., salt, sugar, saturated fat) that make them less healthy than most unprocessed foods—irrespective of processing. In saying that, we don’t know exactly why we tend to overeat UPFs or why they may be harmful to our health (13); future research will be important to understand this further.
I will finish with a quote from a recent paper that complements what I have already discussed:
Consumers need to be correctly informed that healthiness has no direct or absolute correlation either with the number of ingredients, intensity, or number of processes or with the fact that the food has been processed in households or a large industrial plant (14).
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Check back with us next week where we will talk about processed foods for athletes.
Until then, be well!
Patrick Elliott, BSc, MPH
Health and Nutrition Science Communication Officer at Training121
Founder of Just Health — Instagram: @just.health.info
Health Disclaimer: this article is for informational and educational purposes only, and is not a substitute for professional advice. For health advice, speak to a physician or other qualified health-care professional, and for nutrition advice, speak to a qualified nutrition professional (e.g., registered dietitian). The use of information on this site is solely at your own risk.
References
(1) Osté MCJ, Duan MJ, Gomes-Neto AW, Vinke PC, Carrero JJ, Avesani C, Cai Q, Dekker LH, Navis GJ, Bakker SJL, Corpeleijn E. Ultra-processed foods and risk of all-cause mortality in renal transplant recipients. Am J Clin Nutr. 2022;115(6):1646-57. Available at: https://www.sciencedirect.com/science/article/pii/S0002916522002891?via%3Dihub
(2) Chen Z, Khandpur N, Desjardins C, et al. Ultra-Processed Food Consumption and Risk of Type 2 Diabetes: Three Large Prospective U.S. Cohort Studies [published online ahead of print, 2023 Feb 28]. Diabetes Care. 2023;dc221993. Available at: https://diabetesjournals.org/care/article-abstract/doi/10.2337/dc22-1993/148548/Ultra-Processed-Food-Consumption-and-Risk-of-Type?redirectedFrom=fulltext
(3) Moubarac JC, Parra DC, Cannon G, Monteiro CA. Food Classification Systems Based on Food Processing: Significance and Implications for Policies and Actions: A Systematic Literature Review and Assessment. Curr Obes Rep. 2014;3(2):256-72. Available at: https://pubmed.ncbi.nlm.nih.gov/26626606/
(4) Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr. 2018;21(1):5-17. Available at: https://www.cambridge.org/core/journals/public-health-nutrition/article/un-decade-of-nutrition-the-nova-food-classification-and-the-trouble-with-ultraprocessing/2A9776922A28F8F757BDA32C3266AC2A
(5) Monteiro CA, Cannon G, Levy RB, et al. Ultra-processed foods: what they are and how to identify them. Public Health Nutr. 2019;22(5):936-41. Available at: https://www.cambridge.org/core/journals/public-health-nutrition/article/ultraprocessed-foods-what-they-are-and-how-to-identify-them/E6D744D714B1FF09D5BCA3E74D53A185
(6) Aune D, Keum N, Giovannucci E, et al. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies. BMJ. 2016;353:i2716. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4908315/
(7) Ghanbari-Gohari F, Mousavi SM, Esmaillzadeh A. Consumption of whole grains and risk of type 2 diabetes: A comprehensive systematic review and dose-response meta-analysis of prospective cohort studies. Food Sci Nutr. 2022;10(6):1950-60. Available at: https://pubmed.ncbi.nlm.nih.gov/35702290/
(8) Zhao H, Wang M, Peng X, et al. Fish consumption in multiple health outcomes: an umbrella review of meta-analyses of observational and clinical studies. Ann Transl Med. 2023;11(3):152. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9951006/
(9) Afshin A, Micha R, Khatibzadeh S, Mozaffarian D. Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. Am J Clin Nutr. 2014;100(1):278-88. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144102/
(10) Messina M, Sievenpiper JL, Williamson P, Kiel J, Erdman JW. Perspective: Soy-based Meat and Dairy Alternatives, Despite Classification as Ultra-processed Foods, Deliver High-quality Nutrition on Par with Unprocessed or Minimally Processed Animal-based Counterparts. Adv Nutr. 2022;13(3):726-38. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9156366/
(11) Chen Z, Qian F, Hu Y, et al. Dietary phytoestrogens and total and cause-specific mortality: results from 2 prospective cohort studies. Am J Clin Nutr. 2023;117(1):130-40. Available at: https://www.sciencedirect.com/science/article/pii/S0002916522105332
(12) Sun T, Zhang Y, Ding L, Zhang Y, Li T, Li Q. The Relationship Between Major Food Sources of Fructose and Cardiovascular Outcomes: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies. Adv Nutr. 2023;14(2):256-69. Available at: https://www.sciencedirect.com/science/article/pii/S2161831322013163?via%3Dihub
(13) Tobias DK, Hall KD. Eliminate or reformulate ultra-processed foods? Biological mechanisms matter. Cell Metab. 2021;33(12):2314-5. Available at: https://www.sciencedirect.com/science/article/pii/S1550413121004836?via%3Dihub
(14) Petrus RR, Do Amaral Sobral PJ, Tadini CC, Gonçalves CB. The NOVA classification system: A critical perspective in food science. Trends Food Sci Technol. 2021;116:603-8. Available at: https://www.sciencedirect.com/science/article/pii/S0924224421004970
Technical Terms
Statistical significance: This is a term to describe the likelihood of whether a finding in a study is a ‘real’ finding, or if it is the result of chance. Statistical significance is denoted by a p-value, which is usually set at a significance (alpha) level of 0.05. This means that if a result is significant at this level (p ≤ 0.05), we can say that the probability of getting a value as or more extreme than the observed value (under the assumption that the null hypothesis is true) is less than 5%. In other words, it is more likely that this finding is not the result of chance than if the p-value was > 0.05 (although this is not always the case).
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