Certain foods can worsen psoriasis by fueling the systemic inflammation that drives flare-ups. The biggest culprits are alcohol, added sugars, saturated fats, and ultra-processed foods, though individual triggers vary. Psoriasis is powered by overactive immune signaling, and what you eat directly influences the inflammatory molecules at the center of that process.
How Food Fuels Psoriasis Flares
Psoriasis isn’t just a skin problem. It’s driven by an immune system that overproduces inflammatory signaling molecules, particularly TNF-alpha, IL-17, and IL-23. These molecules tell skin cells to multiply too fast and trigger the red, scaly plaques characteristic of the disease. Certain foods ramp up production of these same molecules, while others help dial them down.
The connection runs through a few pathways. Some foods spike insulin, which promotes fat storage and chronic low-grade inflammation. Others damage the gut lining, allowing substances to leak into the bloodstream and provoke immune reactions. Still others directly sensitize immune cells, making them overreact to inflammatory signals. The net effect is the same: more fuel on a fire that’s already burning.
Alcohol
Alcohol is one of the most well-documented dietary triggers for psoriasis. It works through several mechanisms at once. It stimulates the proliferation of both immune cells and keratinocytes (the skin cells that pile up in psoriatic plaques), and it boosts production of pro-inflammatory cytokines. Alcohol and its byproducts also disrupt the skin’s barrier function, making plaques harder to heal.
Beyond triggering flares, alcohol interferes with treatment. In one observational study of 150 psoriasis patients, drinking habits significantly reduced the likelihood of achieving a 75% improvement in symptoms with standard therapy. Alcohol also increases susceptibility to infections, which is especially risky for people on biologic medications that suppress parts of the immune system. Even moderate drinking can be enough to notice a difference in flare frequency and severity.
Sugar and High-Glycemic Foods
Foods that cause rapid blood sugar spikes trigger a cascade that worsens inflammation. When blood sugar rises quickly, your body produces a surge of insulin, a hormone that promotes fat storage, particularly the visceral fat around your organs. That visceral fat is metabolically active, constantly pumping out inflammatory signals.
White bread, pastries, sugary cereals, and sweetened beverages are common offenders. Wheat in particular has a glycemic index of about 71, which means it spikes blood sugar more than many other carbohydrates. High-fructose corn syrup, which can contain up to 90% fructose, follows a different but equally problematic route: the liver converts it into triglycerides and promotes visceral fat accumulation. Some researchers believe it also contributes to increased intestinal permeability, sometimes called “leaky gut,” which allows inflammatory substances to enter the bloodstream.
Even some foods that seem healthy can be surprisingly high-glycemic. Skim milk, for instance, causes faster insulin spikes than whole milk because removing the fat speeds absorption. The core strategy is straightforward: reducing high-glycemic foods lowers insulin production and the visceral fat that sustains chronic inflammation.
Saturated and Trans Fats
A high-fat diet rich in saturated fatty acids worsens psoriatic skin inflammation, and this effect is independent of body weight. Research published in the Journal of Investigative Dermatology found that saturated fatty acids alone, even in lean subjects, were enough to amplify psoriasis-like inflammation. The mechanism is specific: saturated fats sensitize a type of immune cell called myeloid cells, priming them to overreact to inflammatory triggers. Those overactivated immune cells then stimulate keratinocytes, accelerating the cycle of plaque formation.
The practical sources to watch for are fatty cuts of red meat, full-fat processed cheese, butter, fried foods, and anything containing partially hydrogenated oils (trans fats). Trans fats are particularly inflammatory because the body struggles to process them, and they show up in many packaged baked goods, margarine, and fast food.
Ultra-Processed Foods
Ultra-processed foods represent a category beyond just “junk food.” These are products that have undergone complex industrial processing and contain synthetic additives rarely found in a home kitchen: emulsifiers, thickeners, preservatives, artificial flavors. Think soft drinks, packaged snacks, reconstituted meat products, mass-produced breads, sweetened breakfast cereals, and ready-to-heat meals.
The problem goes beyond their high calorie and sugar content. Emulsifiers and thickeners added to these foods have been shown to reduce gut microbial diversity, shifting the balance of bacteria in your digestive system toward a state called dysbiosis. A growing body of evidence links this kind of disrupted gut microbiome to impaired immune regulation and increased psoriasis risk. Your gut bacteria play a direct role in training your immune system, and when their composition is thrown off, the inflammatory signaling that drives psoriasis can intensify. A large prospective cohort study found that higher ultra-processed food consumption was associated with greater psoriasis risk.
Dairy
Dairy is a trigger for some people with psoriasis, though not everyone. Cow’s milk contains casein, a protein that certain individuals have difficulty digesting. When casein irritates the gastrointestinal tract chronically, it can worsen systemic inflammation. Some people with psoriasis report noticeable improvement in their skin after cutting dairy, while others see no change at all.
If you suspect dairy is a factor, the only reliable way to find out is to eliminate it completely for several weeks and then reintroduce it while monitoring your skin. Partial reductions are harder to interpret because low-level irritation can still sustain inflammation without causing obvious digestive symptoms.
Gluten
Gluten is a well-known inflammatory trigger for people with celiac disease, but its role in psoriasis is more nuanced. In susceptible individuals, gluten can increase intestinal permeability and activate the immune system, raising levels of the same inflammatory molecules (TNF-alpha, IL-17, IL-6) that drive psoriasis. The overlap between celiac disease and psoriasis is real but relatively uncommon, with celiac prevalence among psoriasis patients hovering under 1% in large studies.
That said, some people without a formal celiac diagnosis still have elevated antibodies to gluten and experience psoriasis improvement on a gluten-free diet. If you have a family history of celiac disease, unexplained digestive issues alongside your psoriasis, or haven’t responded well to standard treatments, testing for gluten antibodies is worth considering. For the broader psoriasis population, gluten-free eating is not universally helpful.
Nightshade Vegetables
Tomatoes, peppers, eggplant, and potatoes belong to the nightshade family, and you’ll find them on many psoriasis “avoid” lists. They contain alkaloids, including solanine, that some people believe trigger inflammation. However, the scientific evidence connecting nightshades to psoriasis flares is largely anecdotal. No controlled clinical trials have confirmed a clear mechanism.
That doesn’t mean nightshades can’t be a personal trigger for you, just that they aren’t a universal one. If you notice a pattern between eating nightshades and worsening symptoms, an elimination trial is a reasonable approach. But cutting them out preemptively without that pattern means losing nutrient-dense vegetables for an unproven benefit.
What an Anti-Inflammatory Diet Looks Like
Knowing what to avoid is half the picture. The foods that help psoriasis tend to be the mirror image of the triggers above. The Mediterranean diet has the strongest evidence: it’s rich in omega-3 fatty acids from fish, polyphenols from olive oil, fruits, and vegetables, and dietary fiber that supports a healthy gut microbiome. These components actively reduce the inflammatory molecules that drive psoriasis. Omega-3s inhibit production of TNF-alpha and IL-17 while promoting anti-inflammatory compounds called resolvins and protectins. Polyphenols reduce the activation of the specific immune cells (Th17 cells and dendritic cells) responsible for IL-17 and IL-23 production.
Plant-based diets rich in fiber, antioxidants, and phytonutrients also show benefits. Dietary fiber feeds beneficial gut bacteria that produce short-chain fatty acids, which in turn support regulatory immune cells that help keep inflammation in check. The common thread across dietary patterns that help psoriasis is simple: whole foods, minimal processing, low sugar, and plenty of omega-3s and plant compounds.
Finding Your Personal Triggers
Psoriasis triggers are individual. Two people with the same severity can have completely different food sensitivities. The most reliable approach is a structured elimination process: remove the most common triggers (alcohol, added sugars, dairy, gluten, and processed foods) for a minimum of three to four weeks, then reintroduce them one at a time, spacing each reintroduction by at least a few days. Keep a food and symptom diary during this period. Psoriasis can take days to respond to a dietary change, so patience matters more than with, say, a food allergy that produces symptoms within hours.
This process won’t replace medical treatment, but it gives you concrete data about which foods are making your skin worse. Many people find that two or three specific categories are responsible for most of their diet-related flares, while other commonly cited triggers have no effect on them at all.