The foods most likely to worsen rheumatoid arthritis (RA) symptoms are those that drive inflammation: added sugars, processed foods, red meat, fried foods, and alcohol. While no single food causes RA, what you eat can raise or lower the same inflammatory proteins that fuel joint pain, swelling, and stiffness. The American College of Rheumatology acknowledges that diet plays a role in managing rheumatic diseases, and its 2022 integrative guidelines include a conditional recommendation in favor of a Mediterranean-style eating pattern for RA.
Added Sugar and Sugary Drinks
Sugar is one of the clearest dietary triggers for RA flares. When your diet is loaded with added sugars, your body releases pro-inflammatory cytokines, proteins that act as messengers summoning immune cells into action. For someone with RA, this is especially problematic because cytokine levels are already elevated. Piling more sugar on top of that baseline inflammation is like throwing fuel on a fire that’s already burning.
This doesn’t just mean candy and cake. Sugary drinks, flavored yogurts, breakfast cereals, condiments like ketchup and barbecue sauce, and many packaged snacks contain significant amounts of added sugar. UCLA Health has noted that increased sugar intake can directly trigger RA flares through this cytokine pathway. If you’re looking for a single dietary change that’s likely to make the biggest difference, cutting back on added sugar is a strong starting point.
Processed and Ultra-Processed Foods
The American College of Rheumatology is clear on this point: processed food, processed sugar, and “junk food” can harm health and worsen outcomes for people with rheumatic diseases. Ultra-processed foods tend to combine multiple inflammatory ingredients at once, including refined carbohydrates, added sugars, industrial seed oils, and high levels of sodium.
Refined carbohydrates like white bread, pastries, and snack crackers are high-glycemic foods, meaning they spike your blood sugar quickly. That rapid spike fuels the production of compounds called advanced glycation end products, which directly stimulate inflammation. These same compounds accumulate when foods are heavily processed at high temperatures. The Mediterranean diet that rheumatologists recommend emphasizes whole grains and avoids simple carbohydrates for exactly this reason.
Red and Processed Meat
Red meat, particularly processed varieties like bacon, sausage, and deli meats, appears regularly on lists of foods that aggravate RA. The Mediterranean eating pattern recommended by the ACR does not include heavy consumption of red meat. There are a few reasons for this.
Red meat is high in saturated fat, which promotes inflammation through several pathways. Processed meats add sodium and preservatives into the mix, compounding the problem. They also tend to be cooked at high temperatures (grilled, fried, or smoked), which increases the formation of those same inflammation-stimulating compounds found in other high-heat-cooked foods. Replacing red meat with fish is one of the better-studied dietary swaps for RA. Incorporating fish high in omega-3 fatty acids is associated with fewer joint pains and swellings, as well as shorter morning stiffness in RA patients.
Fried Foods and High-Heat Cooking
Fried foods deserve their own spot on this list because of the specific way they promote inflammation. When food is cooked at very high temperatures, whether deep-fried, charred on a grill, or broiled, it produces elevated levels of advanced glycation end products. The Arthritis Foundation identifies these compounds as direct stimulators of inflammation.
French fries, fried chicken, doughnuts, and other deep-fried staples are some of the most concentrated sources. But grilling and broiling meats can produce the same compounds. Cooking methods that use lower temperatures and more moisture, like steaming, stewing, or slow-cooking, generate far fewer of these inflammatory byproducts. This is a case where how you cook matters almost as much as what you cook.
Alcohol
Alcohol’s relationship with RA is complicated, but for most people managing active disease, it belongs on the “worst” list. Many of the most common RA medications are processed by the liver, and alcohol puts additional stress on that same organ. Patients on methotrexate, one of the most widely prescribed RA drugs, are advised to restrict alcohol because of the potential for liver toxicity when the two are combined.
Research from a large clinical database found that moderate drinking (14 or fewer standard drinks per week) did not carry a statistically significant risk of liver problems for people on methotrexate. But increasing alcohol consumption beyond that level was associated with rising risk. Even within the “moderate” range, there was a trend toward more liver enzyme abnormalities at higher intake levels. Beyond the medication interaction, alcohol itself can promote systemic inflammation and disrupt sleep, both of which can make RA symptoms worse.
The Salt Connection
High sodium intake doesn’t always make the “top five” lists, but the evidence against it in RA is growing and worth knowing about. Multiple lines of research show that excess salt disrupts the balance of immune cells in a way that favors inflammation. Specifically, high sodium intake appears to suppress the regulatory immune cells that keep inflammation in check while promoting the pro-inflammatory cells that drive autoimmune conditions.
Animal studies using a collagen-induced arthritis model (the standard lab model for RA) have confirmed that a high-sodium diet worsens the disease. In humans, high sodium intake has been associated with increased risk of RA emerging in the first place. Most of the sodium in a typical diet comes not from the salt shaker but from processed and restaurant foods, which means cutting back on processed foods delivers a double benefit.
What About Nightshade Vegetables?
Tomatoes, peppers, potatoes, and eggplant belong to the nightshade family, and you’ll find plenty of people online who swear these vegetables make their RA worse. The concern centers on solanine, a compound found in nightshades that may irritate the gut and trigger intestinal inflammation, which in turn could heighten joint pain through the gut-joint connection.
But the Cleveland Clinic puts it plainly: it is highly unlikely that avoiding the trace amounts of solanine in nightshade vegetables will ease arthritic pain or inflammation. The research is limited and conflicting, and some nightshades, like purple potatoes, may actually reduce inflammation. If you suspect a specific nightshade bothers you, the Arthritis Foundation suggests a simple experiment. Stop eating it for two weeks, then reintroduce it and see if your symptoms flare. That personal data is more useful than any blanket rule about nightshades, because individual sensitivity varies widely.
A Pattern Matters More Than a Single Food
The most important takeaway from the research is that your overall dietary pattern matters more than any one food. The ACR’s conditional recommendation for a Mediterranean-style diet reflects this: daily fruits, vegetables, whole grains, fish, and healthy fats, with limited red meat, processed food, and added sugar. That pattern consistently lowers markers of inflammation across studies.
You don’t need to eliminate every item on this list overnight. Reducing added sugar and processed food while eating more fish, vegetables, and whole grains shifts the balance toward less inflammation over time. Small, sustained changes tend to stick better than dramatic overhauls, and the cumulative effect on joint pain and stiffness can be meaningful.