While dietary changes won't cure psoriasis or psoriatic arthritis and their related conditions, for many people, eating certain foods — and avoiding others — can provide relief. Doctors are unsure of the connection, but "it appears that nutrition most likely has a role in psoriasis," said Dr. Jennifer Adhout, a dermatologist with a private practice in Los Angeles. "We're just unsure how much."
Research into the connection is still in its early stages, but there are several theories, some clinical trials and anecdotal evidence from doctors and patients about foods that seem to temper or exacerbate symptoms of psoriasis, psoriatic arthritis and related comorbidities.
"While there is not necessarily a magic bullet, dietary changes can help change a person's metabolic profile and be one part of the picture," said Dr. Meagen McCusker, assistant professor and clinical dermatologist at the University of Connecticut.
McCusker said that making dietary changes may not have an immediate impact, but over the long term, the effects on the body will be beneficial.
Here are six ways to tweak your diet to improve your health.
1. Adopt a Mediterranean diet
People with psoriasis and psoriatic arthritis face an increased risk of related conditions, otherwise known as comorbidities, which include coronary artery disease, type 2 diabetes and stroke. Although there is no scientific evidence, anecdotal evidence suggests that following a Mediterranean diet — based on the traditional dietary patterns of Greece, Spain and Southern Italy — may lower the risk of heart disease and certain cancers, diabetes, Alzheimer's, osteoporosis and stroke, lower blood pressure and LDL levels (so-called "bad cholesterol"), improve brain function, eye health and fertility, promote a healthy body weight and increase life span.
The traditional Mediterranean diet is heavy on olive oil, beans, nuts, legumes and seeds, herbs and spices. Fruits, vegetables and grains are also a large part of the diet, while fish and seafood are recommended at least twice a week. Poultry, eggs, cheese and yogurt are eaten in moderation. Sweets and meats, however, do not play a large role in the Mediterranean diet. Daily physical activity, which can reduce the risk of inflammation, is also key.
2. Eat fish
While fish is part of the Mediterranean diet, it's important enough for its own mention.
"The inflammation you see in the skin is just one symptom of inflammation in the whole body," said Adhout.
Foods containing omega-3 fats, found mainly in certain types of fish — particularly salmon, sardines, herring, mackerel and anchovies — have been found to reduce the severity of psoriasis in some patients. In addition, according to a 2006 study published in The Journal of the American Medical Association that analyzed 20 studies involving hundreds of thousands of participants, there is strong evidence that eating fish or taking fish oil is good for the heart and blood vessels, and that eating one to two three-ounce servings of fish per week reduced the risk of dying from heart disease by 36 percent.
Dr. Jennifer Curtiss, a naturopathic doctor and functional nutritionist in Portland, Ore., adds that omega-3s can counter side effects from medications such as inflammation of the kidneys or liver.
In addition, fish oil capsules may lower the risk for heart attack and stroke by decreasing triglyceride levels, although taking too much can actually increase the risk of stroke, according to the National Institutes of Health.
3. Take probiotics
In children, in particular, McCusker has succeeded in tempering psoriasis with probiotics, a bacteria found in the intestines and in foods such as yogurt and some supplements. "We think many skin diseases and other inflammatory diseases originate in the intestines — that's why nutritionals can make an impact and influence the course of disease," McCusker said.
In addition, two daily doses of a new probiotic — L. reuteri NCIMB 30242 — lowered key cholesterol-bearing molecules in the blood, as well as bad and total cholesterol levels, reducing the risk of stroke and heart attack, according to a study presented at the American Heart Association's Scientific Sessions in 2012.
4. Expand your oils
As with fish, certain oils are recommended due to their anti-inflammatory omega-3 fatty acids.
"Olive oil and nut oils are anti-inflammatory," said Adhout, as is avocado oil.
These oils can be used in cooking, for sautéing vegetables or for dressing a salad. Take care not to heat olive or nut oils to a smoking point, said Dr. Jessica Black, author of "Anti-Inflammatory Diet and Recipe Book." When an oil smokes, you run the risk of creating an AGE (advanced glycation end product). AGEs can raise your risk of developing diabetes and heart disease, Black said.
Other oils also have beneficial properties.
"Flax seed, evening primrose, borage and black currant seed oil can be taken as raw oil or in capsule form to help reduce psoriasis symptoms" by stopping cell proliferation and inhibiting cell regeneration, said Curtiss.
There is also some evidence that flax seed may help reduce the risk of heart disease, cancer, stroke and diabetes, while borage, which contains a fatty acid called gamma-linolenic acid, has anti-inflammatory effects that may reduce the risk of heart disease and stroke.
5. Spice it up
A 2012 review by the International Union of Biochemistry and Molecular Biology noted the ability of turmeric — a popular spice in curry — to combat inflammation. Using herbs and spices can help lower salt intake, which decreases blood pressure and lowers the risk of heart attack and stroke, according to the Heart & Stroke Foundation. In addition, herbs and spices have antioxidant properties, and consuming a half to one clove of garlic daily may have a cholesterol-lowering effect of as much as 9 percent, while aged garlic extract has been associated with anticlotting and reductions in systolic blood pressure of about 5.5 percent, according to a 2006 study published in the Medical Journal of Australia.
6. Consider cutting sugars, alcohol and gluten
Just as certain foods are recommended for reducing inflammatory diseases, foods that trigger inflammation should be avoided. According to studies, excess sugar consumption can contribute to type 2 diabetes and heart disease, and can increase cholesterol levels.
And while alcohol is not forbidden, it should be consumed in moderation, as "patients who drink a lot tend to have worse psoriasis," McCusker said. Alcohol consumption can also negatively impact a number of organs. Alcohol damage to the heart can result in stroke, high blood pressure and arrhythmia, while damage to the liver can include cirrhosis, alcoholic hepatitis and fatty liver. Alcohol can also lead to pancreatitis and cancers, and weaken the immune system.
Dairy, caffeine and corn can also trigger inflammation, said Curtiss, and should be avoided when possible. And because gluten may aggravate symptoms of psoriasis, it is important for those with psoriasis to understand how grains such as wheat, barley, rye and triticale affect them.
Eating the right foods can help reduce the symptoms of psoriasis, but more important, a healthy diet can help your body function at its highest level and reduce the risk of a host of comorbidities, improving your quality of life in the process.