Several food groups are consistently linked to psoriasis flares, with sugar, alcohol, red meat, gluten, tomatoes, and dairy topping the list in both clinical research and patient-reported surveys. A national survey of over 1,000 psoriasis patients found that roughly 14% identified sugar and alcohol as personal triggers, followed by tomatoes (7.4%), gluten (7.2%), and dairy (6%). The connection between these foods and psoriasis comes down to inflammation: each one can amplify the specific immune pathways that drive skin cell overproduction and plaque formation.
Sugar and Refined Carbohydrates
Sugar is the most commonly reported dietary trigger among psoriasis patients. A large prospective study using UK Biobank data found that people in the highest quartile of free sugar intake had a 22% greater risk of developing psoriasis compared to those in the lowest quartile. Total sugar and sucrose intake showed similar patterns. The mechanism is straightforward: higher sugar consumption raises systemic inflammation, and psoriasis is fundamentally an inflammatory disease.
Fiber and starch, by contrast, were inversely associated with psoriasis risk in the same study. This suggests the issue isn’t carbohydrates broadly but rather the refined, rapidly absorbed kind found in soft drinks, candy, white bread, and pastries. Swapping these for whole grains, legumes, and vegetables may help reduce the inflammatory load on your body.
Alcohol
Alcohol drives psoriasis flares through a well-documented feedback loop. Ethanol increases production of TNF-alpha, one of the central inflammatory molecules in psoriasis. That TNF-alpha, combined with the oxidative stress alcohol generates, triggers further production of additional inflammatory signals in skin cells. The result is a self-reinforcing cycle: more inflammation leads to more skin cell turnover, which leads to worse plaques.
Beyond flares, alcohol makes psoriasis harder to treat. A meta-analysis found that treatment response is less favorable in people who drink heavily. This applies to both topical and systemic therapies. Even moderate drinking can be enough to notice a difference, though the effect is dose-dependent.
Red Meat and Saturated Fat
Red meat contributes to psoriasis inflammation in two distinct ways. First, it’s rich in saturated fatty acids like palmitic acid and stearic acid (also abundant in butter), which activate a key inflammatory pathway involving TNF-alpha and a group of immune signals called IL-23 and IL-17. These are the same molecules that biologic psoriasis treatments are designed to block.
Second, red meat contains arachidonic acid, a fatty acid that gets incorporated into cell membranes. When the body encounters an inflammatory trigger, arachidonic acid is released and converted into lipid mediators called prostanoids and leukotrienes. Both directly promote psoriasis. One prostanoid, prostaglandin E2, stimulates immune cells called dendritic cells to produce more IL-23, which in turn drives the overproduction of skin cells characteristic of psoriatic plaques. Reducing red meat intake lowers the raw material your body uses to produce these inflammatory compounds.
Gluten
The relationship between gluten and psoriasis is strongest for a specific subset of patients. About 14% of people with psoriasis test positive for antibodies against gliadin (a protein in wheat), compared to roughly 5% of healthy controls. That’s more than double the rate, with a summary odds ratio of 2.36. Among those with elevated antibodies, psoriasis symptoms often improve on a gluten-free diet.
Full celiac disease is less common but still overrepresented: one study found it in 4.3% of psoriasis patients versus zero in matched controls. A larger Israeli registry study found celiac disease in 0.29% of psoriasis patients compared to 0.11% of the general population. If you have psoriasis and experience digestive symptoms like bloating, diarrhea, or unexplained fatigue, testing for gliadin antibodies or celiac disease is worth discussing with your doctor, since a gluten-free diet may improve both your gut and skin symptoms.
Nightshades
Tomatoes, potatoes, eggplants, and peppers belong to the nightshade family, and tomatoes rank as the third most commonly reported psoriasis trigger in patient surveys at 7.4%. Nightshades contain a group of compounds called glycoalkaloids, including solanine, tomatine, chaconine, and solasonine. Plants produce these chemicals as natural pesticides.
Solanine in particular increases intestinal permeability, sometimes called “leaky gut.” When the gut lining becomes more permeable, bacterial fragments and other molecules can cross into the bloodstream and provoke immune responses. For someone whose immune system is already overactive, as in psoriasis, this additional stimulation can be enough to trigger or worsen a flare. The evidence here is less robust than for sugar or alcohol, but many patients report meaningful improvement after removing nightshades for several weeks.
Dairy
Dairy is a polarizing trigger. In the national survey, 6% of psoriasis patients identified it as a trigger food, and 41.3% of respondents had tried removing dairy from their diet at some point. Of those who eliminated dairy, nearly half (47.7%) reported that their psoriasis fully cleared or improved. That’s a notable response rate for a single dietary change, though it clearly doesn’t work for everyone.
Interestingly, the same survey found that psoriasis patients already consumed significantly less dairy and calcium daily compared to the general population, suggesting many had intuitively reduced their intake before being formally surveyed. The specific mechanism linking dairy to psoriasis isn’t fully mapped, but dairy proteins and the saturated fat in full-fat products likely contribute to the same inflammatory pathways triggered by red meat.
How to Identify Your Personal Triggers
Not every food on this list will affect every person with psoriasis. Individual triggers vary, which is why an elimination diet is the most practical tool for figuring out what matters for you. The process involves removing suspected trigger foods for several weeks, stabilizing your diet with nutrient-dense alternatives, and then reintroducing foods one at a time while monitoring your skin. A typical elimination phase lasts three to four weeks, long enough for existing inflammation to calm down and for reintroductions to produce a clear signal.
Start with the highest-probability triggers: sugar, alcohol, and gluten. If you see improvement, reintroduce each one individually, waiting at least a few days between additions. Keeping a food and symptom diary during this process makes patterns much easier to spot. Some people find that a single category (like gluten or dairy) is their primary driver, while others do best with broader changes.
What a Protective Diet Looks Like
The strongest clinical evidence for a psoriasis-friendly eating pattern comes from the Mediterranean diet. In the MEDIPSO randomized trial, 47.4% of participants following a Mediterranean diet for 16 weeks achieved a 75% reduction in their psoriasis severity score, compared to zero in the control group. The Mediterranean diet group saw an average severity score improvement of 3.4 points, while the control group saw no change. These were patients with mild to moderate psoriasis already using stable topical therapy, so the dietary changes produced benefits on top of standard treatment.
The Mediterranean diet emphasizes fruits, vegetables, legumes, whole grains, olive oil, and fish while limiting red meat, processed foods, and added sugar. It’s essentially the inverse of the trigger list: high in omega-3 fatty acids and fiber (both anti-inflammatory), low in the saturated fats and refined sugars that fuel psoriatic inflammation. Rather than thinking of dietary management as a list of restrictions, framing it as a shift toward this pattern tends to be more sustainable and more effective.