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How Ultra-Processed Foods May Fuel Chronic Inflammation
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It’s 6 p.m. and I just got off of work. The last thing I want to do is chop vegetables. So I grab my phone and order delivery. What do I order? A burger with fries and my favorite dessert. Sound familiar?
Here’s what I didn’t know for years: that easy and quick dinner plan isn’t just calories and carbs. It’s what researchers call an ultra-processed food, and a growing body of research suggests these foods may do more than fill me up. They may quietly stoke inflammation in the body, the same slow-burning kind of inflammation linked to heart disease, joint pain, and low energy [1].
I’m not here to make you feel guilty about your last minute dinner decisions. Every now and then, I still go for the less time-consuming option. Instead of the shame, I’m here to walk through what the science actually says about ultra-processed foods and inflammation. I’ll also throw in some practical swaps that fit real life, not a fantasy version of it.
What Are Ultra-Processed Foods?
Let’s clear something up first. “Processed food” is not a dirty word. Washing spinach, freezing berries, and roasting nuts are all forms of processing, and none of that is a problem.
Ultra-processed foods are a different category entirely. Researchers define them as industrial formulations built mostly or entirely from substances extracted or refined from foods, like hydrogenated oils, high-fructose corn syrup, and isolated proteins, plus a list of additives you wouldn’t find in a kitchen [2]. Think colorings, flavor enhancers, emulsifiers, and preservatives. There’s little, if any, actual whole food left in the mix.
A simple test I use: flip the package over and scan the ingredient list. If it’s long, and you spot a handful of words you can’t pronounce or have no idea what they actually are, like maltodextrin, mono- and diglycerides, or “natural flavor,” it’s probably ultra-processed.
The NOVA Classification System
Nutrition scientists sort foods into four groups using something called the NOVA classification system [2]. It’s genuinely one of the most useful tools I’ve found for cutting through food marketing noise.
NOVA Group | What It Means | Everyday Examples |
1. Unprocessed or minimally processed | Whole foods, or foods with only minor changes like drying, freezing, or pasteurizing | Fresh fruit, plain oats, eggs, plain yogurt, frozen vegetables |
2. Processed culinary ingredients | Substances extracted from whole foods, used for cooking | Olive oil, butter, honey, salt |
3. Processed foods | Group 1 or 2 foods with a few added ingredients, usually to preserve or improve taste | Canned beans, cheese, freshly baked bread, canned fish |
4. Ultra-processed foods | Industrial formulations with additives and little to no whole food | Soda, packaged snack cakes, instant noodles, most frozen dinners, sugary cereal |
If you remember nothing else, remember this: Group 4 is where the inflammation research is focused, not Groups 1 through 3.
Why Might Ultra-Processed Foods Trigger Inflammation? (The Biological “Why”)
This is where I want to dig in. There are a handful of direct, plausible mechanisms researchers have identified.
Emulsifiers
Emulsifiers may disrupt your gut lining. Emulsifiers like carboxymethylcellulose (CMC) and polysorbate 80 keep ice cream smooth and salad dressing from separating. In animal studies, these common additives thinned the protective mucus layer in the gut and altered gut bacteria in ways associated with low-grade inflammation [3]. A follow-up controlled feeding trial in healthy humans found that CMC modestly increased abdominal discomfort and disrupted gut microbiota diversity over just 11 days [4]. That’s a small, short study, so it’s not the final word, but it’s a real signal worth taking seriously.
High-Heat Processing
High-heat processing creates AGEs. When starchy or sugary foods are processed at high heat, a reaction forms compounds called advanced glycation end products, or AGEs. A systematic review of controlled trials found that diets high in AGEs were linked to increased inflammatory markers like TNF-alpha in the body [5].
Blood Sugar Spikes
Blood sugar spikes add fuel to the fire. Many ultra-processed foods are quickly digested, added-sugar-heavy, and low in fiber, which can cause rapid blood sugar spikes. The American Heart Association has noted that excess added sugar intake is associated with oxidative stress and inflammation, on top of its effects on cholesterol and insulin resistance [6].
Stripped Fiber
Stripped fiber may starve your gut bacteria. Whole foods bring fiber that feeds beneficial gut bacteria, which in turn produce anti-inflammatory compounds. Ultra-processed foods are often fiber-poor, and Harvard Health notes this may shift gut bacteria toward types associated with more inflammation [7].
Excess Calories
Excess calories may play a supporting role. In a landmark NIH inpatient trial, adults eating an ultra-processed diet ate about 500 more calories per day than when eating an unprocessed diet, even though meals were matched for calories, sugar, fat, and fiber on paper [8]. Extra body fat itself can act as an inflammatory tissue, so weight gain may be one more indirect pathway.
Measurable Health Risks: What the Research Actually Shows
I want to be straight with you here, because a lot of headlines overstate this stuff. Let’s look at what’s actually been measured.
The most comprehensive look at this topic is a 2024 umbrella review published in The BMJ, which pooled dozens of existing meta-analyses. It found that higher ultra-processed food intake was consistently associated with a higher risk of 32 different adverse health outcomes, spanning heart disease, type 2 diabetes, common mental disorders, and all-cause mortality [9]. That’s association, not proof of direct causation for most outcomes, and the authors themselves called for more research into the exact mechanisms.
On inflammation specifically, here’s what more targeted studies have found:
Study | Population | Key Finding |
Lane et al. (2022) | 2,018 adults, Melbourne Collaborative Cohort Study | Every extra 100g/day of ultra-processed food was associated with a 4% higher hs-CRP, an inflammation marker, even after adjusting for BMI |
Sajan et al. (2025) | 9,254 U.S. adults, NHANES data | Adults in the highest ultra-processed food intake group had an 11% higher likelihood of elevated hs-CRP than those in the lowest group |
Hall et al. (2019) | 20 adults, NIH inpatient randomized trial | 20 adults, NIH inpatient randomized trial |
I find that last one especially convincing because it’s a randomized controlled trial, the gold standard for showing cause and effort, not just correlation. The inflammation-marker studies are cross-sectional, meaning they show a real statistical link, but can’t prove the food alone caused the inflammation. Other factors, like overall diet quality and activity level, are part of the picture too.
Which Ingredients Tend to Be the Biggest Triggers?
If you’re wondering where to actually focus your attention, these are the ingredients most often flagged in the research above:
- Added sugars and high-fructose corn syrup — linked to blood sugar spikes and oxidative stress [10]
- Emulsifiers like carboxymethylcellulose and polysorbate 80 — may disrupt gut lining and microbiota [3, 4].
- Hydrogenated or heavily refined oils — associated with less favorable fat profiles in the diet
- Highly heat-processed starches and proteins — a source of dietary AGEs [5].
- Excess sodium and preservatives — common in shelf-stable packaged foods, and tied to broader cardiometabolic risk
Notice what’s not on this list: coffee, olive oil, canned beans, or plain frozen vegetables. Processing itself isn’t the enemy. It’s the industrial formulation and additive load that the research keeps pointing back to.
Actionable, Non-Judgmental Alternatives
Here’s my honest take: nobody needs a perfect diet, and an all-or-nothing approach usually backfires. Small, doable swaps beat a total overhaul you’ll abandon by Thursday.
- Add before you subtract. Instead of banning your favorite snack, add a piece of fruit or a handful of nuts alongside it. Crowding in whole foods matters more than perfect restriction.
- Try the ingredient test. Before buying a packaged item, glance at the label. If it reads like a chemistry set, that’s a red flag to stay clear and look for a better option.
- Cook with moist heat when you can. Boiling, steaming, and stewing produce fewer AGEs than frying or charring [5]. Even swapping one fried meal a week for a steamed or roasted one is progress.
- Batch-cook a base you actually like. A pot of beans, a tray of roasted vegetables, or grilled chicken breasts in the fridge make the “easy” choice a whole-food choice on busy nights.
- Keep one or two convenience foods you love, guilt-free. Sustainable eating includes joy. A goal of “mostly whole foods, sometimes ultra-processed” is realistic and still meaningfully different from an all-UPF pattern.
- Read for fiber and protein, not just calories. Foods with fiber and protein tend to be more filling and less likely to be ultra-processed in the first place.
None of this requires perfection. It requires direction.
Putting It All Together
Ultra-processed foods aren’t poison, and eating one won’t undo your health. But the research is fairly consistent: regularly eating a diet heavy in ultra-processed foods is associated with higher inflammatory markers and a long list of chronic disease risks, likely through a combination of gut microbiome disruption, blood sugar spikes, AGE formation, and excess calorie intake [8, 9].
The goal isn’t a perfect pantry. It’s shifting the balance, one realistic swap at a time, toward more whole foods and fewer industrial formulations. Your gut bacteria, and probably your joints and energy levels too, will likely thank you for it.
Want an easy place to start? I put together a free Anti-Inflammatory Food Swap Guide, a simple, judgment-free cheat sheet of whole-food swaps for the most common ultra-processed staples in your kitchen. Grab your free copy below and start with just one swap this week.
[Download: Free Anti-Inflammatory Food Swap Guide]
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[1] Lane, M. M., Lotfaliany, M., Forbes, M., Loughman, A., Rocks, T., O’Neil, A., Machado, P., Jacka, F. N., Hodge, A., & Marx, W. (2022). Higher ultra-processed food consumption is associated with greater high-sensitivity C-reactive protein concentration in adults: Cross-sectional results from the Melbourne Collaborative Cohort Study. Nutrients, 14(16), 3309. https://doi.org/10.3390/nu14163309
[2] Monteiro, C. A., Cannon, G., Levy, R. B., Moubarac, J.-C., Louzada, M. L., Rauber, F., … Jaime, P. C. (2019). Ultra-processed foods: what they are and how to identify them. Public Health Nutrition, 22(5), 936–941. doi:10.1017/S1368980018003762
[3] Chassaing, B., Koren, O., Goodrich, J. et al. Dietary emulsifiers impact the mouse gut microbiota promoting colitis and metabolic syndrome. Nature 519, 92–96 (2015). https://doi.org/10.1038/nature14232
[4] Chassaing, B., Compher, C., Bonhomme, B., Liu, Q., Tian, Y., Walters, W., Nessel, L., Delaroque, C., Hao, F., Gershuni, V., Chau, L., Ni, J., Bewtra, M., Albenberg, L., Bretin, A., McKeever, L., Ley, R. E., Patterson, A. D., Wu, G. D., Gewirtz, A. T., & Lewis, J. D. (2022). Randomized controlled-feeding study of dietary emulsifier carboxymethylcellulose reveals detrimental impacts on the gut microbiota and metabolome. Gastroenterology, 162(3), 743–756. https://doi.org/10.1053/j.gastro.2021.11.006
[5] Clarke, R. E., Dordevic, A. L., Tan, S. M., Ryan, L., & Coughlan, M. T. (2016). Dietary Advanced Glycation End Products and Risk Factors for Chronic Disease: A Systematic Review of Randomised Controlled Trials. Nutrients, 8(3), 125. https://doi.org/10.3390/nu8030125
[6] Johnson, R. K., Appel, L. J., Brands, M., Howard, B. V., Lefevre, M., Lustig, R. H., Sacks, F., Steffen, L. M., & Wylie-Rosett, J. (2009). Dietary sugars intake and cardiovascular health: A scientific statement from the American Heart Association. Circulation, 120(11), 1011–1020. https://doi.org/10.1161/CIRCULATIONAHA.109.192627
[7] Harvard Health Publishing. (2026, March 30). Quick-start guide to an anti-inflammation diet. Harvard Medical School. https://www.health.harvard.edu/diet-and-nutrition/quick-start-guide-to-an-antiinflammation-diet
[8] Hall, K. D., Ayuketah, A., Brychta, R., Cai, H., Cassimatis, T., Chen, K. Y., Chung, S. T., Costa, E., Courville, A., Darcey, V., Fletcher, L. A., Forde, C. G., Gharib, A. M., Guo, J., Howard, R., Joseph, P. V., McGehee, S., Ouwerkerk, R., Raisinger, K., Rozga, I., Stagliano, M., Walter, M., Walter, P. J., Yang, S., & Zhou, M. (2019). Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake. Cell Metabolism, 30(1), 67–77. https://doi.org/10.1016/j.cmet.2019.05.008
[9] Lane, M. M., Gamage, E., Du, S., Ashtree, D. N., McGuinness, A. J., Gauci, S., Baker, P., Lawrence, M., Rebholz, C. M., Srour, B., Touvier, M., Jacka, F. N., O’Neil, A., Segasby, T., & Marx, W. (2024). Ultra-processed food exposure and adverse health outcomes: Umbrella review of epidemiological meta-analyses. BMJ, 384, e077310. https://doi.org/10.1136/bmj-2023-077310
[10] Johnson, R. K., Appel, L. J., Brands, M., Howard, B. V., Lefevre, M., Lustig, R. H., Sacks, F., Steffen, L. M., & Wylie-Rosett, J. (2009). Dietary sugars intake and cardiovascular health: A scientific statement from the American Heart Association. Circulation, 120(11), 1011–1020. https://doi.org/10.1161/CIRCULATIONAHA.109.192627