context: Psoriatic arthritis ( Ps A) is a type of swelling in the joints that happens in people who have psoriasis. That's a skin condition that causes red, scaly, itchy patches on the elbows, knees, or scalp. About 30% of the people who have psoriasis get Ps A. If you have it, you might wonder if changing your diet could help you feel better. The Psoriasis Foundation says there's no real evidence it'll have a major impact. But it did find that many people with psoriasis had milder symptoms when they ate healthier foods. And there's definitely no downside to eating healthier. With that in mind, let's look at some of the most popular diets and how they might help if you have psoriatic arthritis. This is any basic diet that helps you shed pounds, which is a good thing. Being overweight can raise your risk for psoriatic disease. And losing weight can make psoriasis less severe. Doctors aren't sure why this is, but they do know that fat tissue releases proteins that cause swelling. In a weight loss diet, you limit fats, sugars, and carbohydrates. You eat more fruits, vegetables, lean meats, and low-fat dairy items. When you lose weight, you'll not only feel better -- you'll lower your risk for getting other diseases, too, like diabetes and high blood pressure. Foods like fatty red meats, dairy, refined sugars, processed foods, and possibly vegetables like potatoes, tomatoes, and eggplants (you might hear them called nightshades) may all cause inflammation. Avoid them and choose fish, like mackerel, tuna, and salmon, which have omega-3 fatty acids. Those have been shown to reduce inflammation. Carrots, sweet potatoes, spinach, kale, and blueberries are good choices, too. This plan has an official-sounding name, but it's really an offshoot of the paleo diet. You'll cut back on gluten and refined sugar. There's an elimination phase where you'll avoid grains, legumes, nightshades, dairy, eggs, coffee, alcohol, sugar, oil, and food additives. The idea is to get rid of anything that might cause inflammation while bulking up on nutrient-dense foods, bone broth, fermented foods, and exercise. You can work the excluded foods back in slowly, figuring out what works for you and what doesn't. This plan may help people with colitis and Crohn's disease achieve remission. That's promising news, though there are no studies on how it works with psoriatic arthritis. Research shows that as many as 25% of people with psoriasis may be sensitive to this protein that's found in wheat and barley. You won't find it in fruits and vegetables, rice, meat, beans, potatoes, and dairy. Talk to your doctor before you start this diet. They may test your blood to see if you're allergic to gluten. While doctors say there's no such thing as a leaky gut or a specific diet for it, you're still likely to hear about it. People who believe it say that bacteria and toxins enter your bloodstream through openings that result from Crohn's disease or taking too much aspirin. In fact, research shows that a little bit of a leaky gut (your doctor might call it intestinal permeability) can help you absorb water and nutrients. Fad diets have popped up telling you to stay away from foods with high sugar content (whether they're fruits or processed products) or that things like yeast, gluten, and lactose can damage your intestinal wall. If you have problems with these things, not eating them will make you feel better, as will cutting back on sugary, processed foods. Never trust anyone trying to sell you leaky gut diet products. Another eating plan that works well for people with irritable bowel syndrome might be worth a try. FODMAP is a nickname for a group of carbohydrates called fermentable oligo-saccharides, disaccharides, mono-saccharides, and polyols that are hard to digest. They're found in fruits, honey, some dairy, wheat, onions, garlic, legumes, and artificial sweeteners. Though there's no proof it works for psoriatic arthritis, you can cut them from your diet for 4 to 6 weeks, then gradually work them back in and see if you feel better. A 2014 study showed that eating a diet high in extra-virgin olive oil could make psoriasis symptoms less severe. That's because it has omega-3s. It also contains oleocanthal, which relieves swelling. If you choose this way of eating, you'll get to have lots of cold-water fish, whole grains, fruits, and vegetables. People with psoriasis said their symptoms improved while eating this plan, which calls for boosting fruits and veggies while cutting back on nightshades and junk food. But keep in mind that self-reported results are not the same as scientifically tested and proven results. Positive changes often follow when you add healthier foods to the menu. Also called the caveman diet, this way of eating favors meat, fish, eggs, fruits, and vegetables. You'll avoid all grains, beans, sugary snacks, and dairy. Doctors have no proof that the paleo diet stops Ps A symptoms. But you could have less swelling because you're not eating fatty foods and dairy products. Don't get started with any of these diets until you get your doctor's OK. They can keep track of the changes you're making and determine whether they'll help or worsen your Ps A symptoms. Also, get exercise along with any food changes you make. It's good for your joints and will also ease swelling and arthritic pain. When you have psoriatic arthritis, you want to stay away from foods that can make the inflammation in your body worse. These include: Alcohol: It makes your liver work harder and disrupts the way your organs work together. Sugar: It sends out things called cytokines that create inflammation in your body. Processed foods: They contain trans fats that can start inflammation throughout your body. Diet soda: If it's sweetened with aspartame, your body might think that's a foreign substance and start an immune response. Fried foods: They contain trans fats that can start inflammation throughout your body. Processed meats: They contain saturated fats, which can make inflammation worse. Red meat: It contains saturated fats, which can make inflammation worse. Dairy: These foods contain saturated fats, which can make inflammation worse. You can add these foods in place of the ones above to help keep inflammation in check: Fruits and vegetables: Go for berries and dark, leafy greens. They're high in antioxidants, which keep your immune system healthy and may fight inflammation. Beans and whole grains: They're high in fiber, which keeps levels of C-reactive protein ( CRP) in your blood in check. High CRP can mean you have inflammation. Fatty fish, avocados, flaxseed oil, and olive oil: They're high in omega-3 fatty acids, which cut the amount of inflammatory proteins in your body. Turmeric, ginger, and cayenne: These spices all keep inflammation in check. Green, white, and black teas: They're high in polyphenols, which rev your immune system.