Does Processed Food Cause Inflammation? The Link Explained

November 28, 2025 •

4 min read

According to a 2024 study, more than half of the calories consumed at home by U.S. adults come from ultra-processed foods. This heavy reliance on convenience has led to growing concern over whether processed food causes inflammation and contributes to chronic diseases.

Quick Summary

Processed foods, particularly ultra-processed varieties, have been strongly linked to chronic low-grade inflammation. This is driven by ingredients like added sugars, unhealthy fats, and artificial additives, which can disturb the gut microbiome, increase inflammatory markers, and damage bodily tissues over time.

Key Points

Ultra-Processed Foods Drive Inflammation: Research consistently links high consumption of ultra-processed foods (UPFs) to elevated systemic inflammatory biomarkers, especially high-sensitivity C-reactive protein (hs-CRP).
Gut Microbiome is Key: UPFs disrupt the balance of gut bacteria by being low in fiber and containing artificial additives, leading to increased intestinal permeability and a pro-inflammatory state.
Added Sugar and Unhealthy Fats are Culprits: The high amounts of added sugars, refined carbohydrates, and trans fats in UPFs are potent inflammatory triggers that can cause blood sugar spikes and increase bad cholesterol.
Chronic Inflammation Poses Long-Term Risks: Persistent, low-grade inflammation fueled by UPFs is a driving mechanism behind chronic conditions like heart disease, type 2 diabetes, and neurological diseases.
Whole Foods Offer an Anti-Inflammatory Solution: Shifting towards a diet rich in whole foods—fruits, vegetables, whole grains, and healthy fats—can provide antioxidants, fiber, and omega-3s that actively combat inflammation.
Read Labels to Identify Inflammatory Ingredients: A simple method for identifying potentially inflammatory foods is to check the label for long lists of unrecognizable ingredients, including partially hydrogenated oils and artificial additives.

Understanding Processed vs. Ultra-Processed Food

To grasp the relationship between food and inflammation, it's crucial to distinguish between different levels of food processing. Not all processed foods are inherently bad; some processing methods, like freezing or pasteurization, are done for safety and preservation. The real concern lies with ultra-processed foods (UPFs).

What are ultra-processed foods?

UPFs are industrial formulations often made with five or more ingredients, many of which are not used in home cooking. They are engineered to be highly palatable and addictive but are typically lacking in fiber and essential nutrients.

Common UPF culprits:
- Packaged snacks, cookies, and chips
- Sugary drinks and sodas
- Processed meats like hot dogs and salami
- Instant noodles and frozen ready meals
- Refined white bread and pastries

The Inflammatory Cascade Triggered by Processed Foods

The link between high UPF consumption and chronic, low-grade inflammation is well-documented. This systemic inflammation isn't the kind you see with an injury but rather a silent, persistent state that can wear down the body's tissues and contribute to serious health problems over time.

Gut Microbiome Disruption

UPFs are often low in fiber, which is vital for feeding beneficial gut bacteria. Without enough fiber, the diversity of the gut microbiome decreases, allowing harmful bacteria to flourish. This imbalance, known as dysbiosis, can increase intestinal permeability, also called 'leaky gut'. When the gut lining becomes more permeable, toxins like lipopolysaccharides (LPS) can enter the bloodstream, triggering an immune response and promoting systemic inflammation.

Ingredient-Specific Inflammation

Beyond the lack of fiber, specific ingredients commonly found in UPFs are known to be pro-inflammatory.

Added Sugars: High intake of added sugars, especially high-fructose corn syrup, causes rapid spikes in blood glucose and insulin levels, which promotes an inflammatory state. Research has shown a link between sugary beverages and elevated inflammatory markers like C-reactive protein (CRP).
Unhealthy Fats: Trans fats (listed as 'partially hydrogenated oils') raise LDL ('bad') cholesterol and are highly inflammatory. Many UPFs are also high in the wrong balance of fats, with an excess of omega-6 fatty acids compared to omega-3s, which can also promote inflammation.
Artificial Additives: Emulsifiers, artificial sweeteners, and preservatives are added to enhance flavor and extend shelf life. Animal studies suggest these additives can negatively alter the gut microbiome and potentially contribute to inflammation, though human studies are still ongoing.

Chronic Inflammation and Associated Health Risks

Sustained, low-grade inflammation from a diet high in processed foods is a key underlying mechanism for several modern health challenges. It contributes to conditions by damaging cells and organs throughout the body.

Cardiovascular Disease: Inflammation can damage the lining of blood vessels (endothelial cells), leading to atherosclerosis, which increases the risk of heart attack and stroke.
Metabolic Disorders: The cycle of blood sugar spikes and insulin resistance fuels inflammation, significantly raising the risk of type 2 diabetes and metabolic syndrome.
Neurological Diseases: Chronic inflammation can impact the gut-brain axis, contributing to neuroinflammation linked with cognitive decline and an increased risk of neurological diseases like Alzheimer's and Parkinson's.
Other Conditions: The link is also seen with obesity, some cancers, and inflammatory bowel diseases like Crohn's and ulcerative colitis.

Comparison: Processed vs. Whole Foods


Feature	Processed Foods (e.g., Ultra-Processed)	Whole Foods (e.g., Minimally Processed)
Nutrient Density	Often low in essential nutrients like vitamins, minerals, and fiber.	Rich in fiber, antioxidants, vitamins, and minerals.
Ingredient List	Long list, often includes additives, refined sugars, unhealthy fats, and preservatives.	Short and recognizable list of natural ingredients.
Impact on Gut Health	Disrupts the microbiome and can increase intestinal permeability.	Supports a diverse and healthy gut microbiome.
Inflammatory Potential	Promotes chronic, low-grade inflammation.	Contains anti-inflammatory compounds like omega-3s and polyphenols.
Health Outcomes	Associated with higher risk of obesity, diabetes, heart disease, and some cancers.	Linked to better overall health and reduced risk of chronic diseases.
Satiety Signals	Can suppress natural hormones that signal fullness, leading to overconsumption.	Supports natural satiety and metabolism.

How to Reduce Processed Food-Related Inflammation

Reducing inflammation through diet is an achievable goal, often requiring small, consistent changes.

Prioritize Whole Foods: Build your meals around unprocessed or minimally processed foods like fruits, vegetables, whole grains, and lean proteins.
Read Labels Carefully: Learn to identify and avoid common inflammatory culprits like trans fats, high-fructose corn syrup, and artificial additives.
Choose Healthy Fats: Swap inflammatory fats (trans fats, excess omega-6s) for healthy ones rich in omega-3s, found in fatty fish, flaxseeds, and walnuts.
Boost Fiber Intake: Increase your consumption of fiber-rich foods, including legumes, vegetables, and whole grains, to nourish a healthy gut microbiome.
Cook More at Home: Preparing meals from scratch gives you full control over ingredients and helps you avoid hidden inflammatory additives.
Stay Hydrated: Drink plenty of water and unsweetened beverages. Replace sugary sodas with water, herbal tea, or naturally infused water.

Conclusion

The scientific evidence strongly indicates that a diet high in ultra-processed foods contributes significantly to chronic, low-grade inflammation. This is not due to a single component but a combination of harmful ingredients like added sugars, unhealthy fats, and artificial additives, along with a lack of beneficial nutrients like fiber. While the link is particularly strong for high-sensitivity C-reactive protein (hs-CRP) in adults, research also suggests associations with other inflammatory markers and several chronic diseases. By shifting focus toward a diet rich in whole, unprocessed foods and making mindful choices, individuals can take meaningful steps to reduce inflammation and support their long-term health. For more detailed information on healthy eating patterns, a reliable resource is the American Heart Association.

Frequently Asked Questions

Processed foods are simply altered from their natural state, like frozen vegetables or canned beans. Ultra-processed foods (UPFs), however, are industrial formulations made with numerous ingredients, including additives, and are designed to be highly palatable but are low in nutrients.

Processed food causes inflammation primarily through its ingredients and nutritional profile. It's often high in added sugars, unhealthy fats, and refined carbs, which increase blood sugar and promote inflammatory pathways. The lack of fiber and presence of additives can also disrupt the gut microbiome, further triggering an immune response.

Some of the most inflammatory processed foods include sugary drinks, processed meats (hot dogs, bacon), fried foods, commercial baked goods (cookies, pastries), and refined grains (white bread).

Yes, minimally processed foods can be part of a healthy diet. Examples include frozen fruits and vegetables, pasteurized milk, and canned fish. The key is to prioritize whole foods and limit the consumption of ultra-processed items that contain inflammatory ingredients.

Acute, short-term inflammation from an occasional processed meal is not a major concern. However, addressing chronic, low-grade inflammation built up over time requires a sustained dietary shift towards whole foods, which can lead to improvements over weeks or months, though individual results vary.

For an anti-inflammatory diet, focus on whole foods rich in antioxidants and healthy fats. Incorporate fruits (especially berries), leafy greens, whole grains, fish high in omega-3s (salmon), nuts, and seeds into your meals.

Yes, processed foods can significantly harm gut health by reducing the diversity of beneficial bacteria due to a lack of fiber and potentially irritating the gut lining with additives. This can lead to digestive issues and, in some cases, inflammatory bowel conditions.