Several categories of food are consistently linked to higher levels of inflammation in the body: ultra-processed foods, refined carbohydrates, processed meats, foods high in certain fats, added sugars, and alcohol. The common thread is that these foods trigger your immune system to produce inflammatory molecules, even when there’s no infection or injury to fight. Over time, this low-grade, chronic inflammation contributes to heart disease, type 2 diabetes, and other serious conditions.
Ultra-Processed Foods
Ultra-processed foods are the single biggest dietary driver of chronic inflammation for most people. This category is broad: microwaveable dinners, hot dogs, chicken nuggets, dehydrated soups, packaged baked goods, sugary cereals, biscuits, and bottled sauces all qualify. A 2025 report in the journal Nutrients found that ultra-processed foods can alter gut bacteria, damage the intestinal lining, and activate inflammatory genes inside cells. That combination means these foods don’t just add empty calories; they actively reprogram how your body handles inflammation at a cellular level.
Refined Carbohydrates and White Flour
White bread, white pasta, white rice, refined cereals, and anything made with white flour promote a pro-inflammatory state in the body. The mechanism is straightforward: refined carbohydrates break down into sugar rapidly, causing a sharp spike in blood sugar. Your body responds with a surge of insulin, and when this cycle repeats meal after meal, it leads to insulin resistance, the accumulation of visceral fat (the deep belly fat surrounding your organs), and a steady output of pro-inflammatory molecules called cytokines. These cytokines are the same signaling chemicals your immune system uses during an infection, but in this case they circulate without purpose, damaging tissues over time.
Whole grains like oats, barley, and bran behave differently. Their fiber slows digestion, blunting the blood sugar spike and reducing the downstream inflammatory cascade.
Processed and Cured Meats
Bacon, sausages, deli meats, and hot dogs are significant dietary sources of compounds called advanced glycation end products, or AGEs. These form when proteins and sugars in meat react during high-heat cooking, curing, or prolonged storage. Once you eat them, AGEs accumulate in your body and trigger both oxidative stress and inflammation. This is separate from the saturated fat content of these meats; the processing itself creates inflammatory compounds that wouldn’t be present in fresh, unprocessed cuts cooked at lower temperatures.
Omega-6 Fats and the Balance That Matters
Not all fats are inflammatory, and the picture is more nuanced than “fat is bad.” The key issue is the ratio between omega-6 and omega-3 fatty acids in your diet. Omega-6 fats, found abundantly in soybean oil, corn oil, sunflower oil, and many fried and packaged foods, get converted into arachidonic acid in your cells. Arachidonic acid is a building block for potent inflammatory molecules, including prostaglandins and leukotrienes, the same chemicals responsible for the swelling and pain you feel after an injury.
Omega-3 fats from fish, flaxseed, walnuts, and leafy greens work in the opposite direction. They compete with omega-6 for space in your cell membranes. When omega-3s win that competition, your cells produce fewer inflammatory signals and more compounds that actively resolve inflammation. A diet heavy in fried foods and vegetable oils but light on fish and nuts tips that balance sharply toward inflammation. High omega-6 intake also appears to blunt the anti-inflammatory and inflammation-resolving effects of whatever omega-3s you do consume, making the imbalance doubly harmful.
Deep-fried foods deserve special mention because they concentrate these oils at high temperatures, which also generates trans fats. Industrial trans fats, still present in some fried and packaged foods, are among the most reliably inflammatory substances in the food supply.
Added Sugars
Sugary drinks, candy, flavored yogurts, and sweetened cereals all deliver large doses of sugar with little else to slow absorption. The inflammatory effect of added sugar works largely through the same insulin resistance pathway as refined carbohydrates: repeated blood sugar spikes promote visceral fat storage, and visceral fat tissue itself pumps out inflammatory cytokines. The type of sugar, whether it’s table sugar, high-fructose corn syrup, or pure glucose, matters less than the total amount. One controlled trial that had participants drink beverages sweetened with fructose, glucose, or high-fructose corn syrup found no meaningful difference in inflammatory markers between the three. The sugar itself, regardless of source, is the problem.
Alcohol
Alcohol promotes inflammation primarily by damaging the lining of your intestines. In alcohol-dependent individuals, researchers have documented increased intestinal permeability, sometimes called “leaky gut,” which allows bacterial products to escape from the gut into the bloodstream. Once there, these bacterial fragments trigger a systemic immune response. Interestingly, the degree of gut damage doesn’t scale neatly with how much someone drinks. In one study published in PNAS, people who consumed similar amounts of alcohol showed very different levels of intestinal permeability, suggesting individual biology plays a large role in how much inflammation alcohol causes.
Even for moderate drinkers, alcohol can still shift the gut microbiome and contribute to low-level inflammation over time, particularly when combined with other inflammatory foods.
Butter, Cheese, and Saturated Fat
Butter, ice cream, and high-fat cheese are often listed as inflammatory foods, and Harvard Health includes them on its list of inflammation-promoting items. But the evidence on dairy specifically is surprisingly mixed. A meta-analysis of 11 randomized controlled trials found that higher dairy consumption actually reduced several inflammatory markers compared to low or no dairy intake, including C-reactive protein (a standard blood test for inflammation) and two key inflammatory signaling molecules. However, when the analysis was restricted to the most rigorous study designs, those benefits disappeared. The honest answer is that dairy’s effect on inflammation likely depends on the type of product, how it’s processed, and individual factors like gut bacteria composition. Full-fat, highly processed dairy products like ice cream are a different food than plain yogurt or aged cheese, even though they share a label.
Nightshade Vegetables Are Likely Fine
Tomatoes, peppers, eggplant, and potatoes belong to the nightshade family, and you’ll find claims online that they cause inflammation. There is no clinical evidence supporting this for the general population. No large-scale studies have demonstrated that nightshades promote inflammation, and they’re rich in vitamins and antioxidants that may do the opposite. Some people with autoimmune conditions like rheumatoid arthritis or psoriasis report feeling better when they reduce nightshades, but this remains anecdotal. If you don’t have an autoimmune condition, there’s no scientific reason to avoid them.
What Reducing These Foods Actually Looks Like
Shifting away from inflammatory foods doesn’t require perfection. The Mediterranean diet and the DASH diet both follow the same core principles: more fruits, vegetables, whole grains, legumes, fish, nuts, seeds, and olive oil; less processed food, refined flour, added sugar, and red meat. Specific anti-inflammatory components in these foods include fiber (especially from legumes and whole grains), omega-3 fatty acids (from fatty fish like salmon, mackerel, and sardines), and polyphenols, the plant chemicals found in berries, dark chocolate, tea, apples, onions, and coffee.
One thing worth knowing: inflammatory markers don’t drop overnight. A four-week pilot study measuring common inflammation markers like C-reactive protein and IL-6 found no substantial changes in that timeframe, even with a structured dietary intervention. This doesn’t mean the changes aren’t working. It means inflammation built up over years of dietary patterns takes time to reverse, and short-term blood tests may not capture the gradual improvement happening in your tissues. Consistency over months matters more than any single meal or week of clean eating.