Gluten-Free Diets for Psoriasis: Facts and Myths
Can a gluten-free diet (GFD) cure psoriasis? This case report shares one example of a 53-year-old man with severe psoriasis. His psoriasis had required treatment with systemic medications, including a powerful immune suppressing medication called cyclosporine. When he developed abdominal pain, diarrhea, and vitamin deficiencies, his physicians were concerned. He underwent testing with an endoscopy and biopsy of his gastrointestinal (GI) tract. These showed inflammation, and because of this severe inflammation, he was put on a gluten-free diet (GFD).
One month later, his GI symptoms had improved markedly. More surprising, his skin had cleared.
This was a great outcome with significant exposure in the professional community and the media. However, it has also led to several myths.
Gluten-free Diets in Psoriasis: Only Some Patients Are Likely to Benefit
While there are some patients with psoriasis who may see improvement on a gluten-free diet, the research to date indicates that it's probably a small number.
Because of the limited research in this area, we don't have a large amount of data. However, the case reports and small research studies performed to date, do point to certain guidelines.
To start with, GFD diets are recommended for all patients with celiac disease, due to the risk of severe inflammation of the GI tract. How many patients with psoriasis will develop celiac disease? Not many.
It is known that patients with psoriasis are at higher risk of celiac disease, with an estimated 2-3 fold higher risk of celiac disease than the general population. However, this is still a very small number. It is believed that about 1 in 1000 individuals will develop celiac disease, although this number can vary significantly depending on the population being studied. For psoriasis patients, that number rises to about 3 in 1000 patients. This is higher but is still a small number.
Some patients with psoriasis may develop antibodies to components of gluten or other substances without ever developing actual celiac disease. One type of antibodies, called anti-gliadin antibodies (AGA), has been found at a higher rate in psoriasis patients. In one summary paper that combined the results of several studies, it was found that about 5% of study subjects without psoriasis had AGA. In subjects with psoriasis, that number rose to 14%: that's about 1 in 7 psoriasis patients with AGA.
We still don't know the full implications of AGA, but some research suggests that these patients may benefit from a GFD. In one study, 33 patients with AGA followed a GFD for 3 months. Of these patients, 73% had an improvement in their psoriasis. In a comparison group of 6 psoriasis patients without AGA, none of the patients experienced improvement after the GFD.
The implications of the AGA aren't clear, as a GFD doesn't work for all patients with AGA. In a report of 3 patients with AGA, none improved after 6 months on a GFD.
A Medical History and Testing Are Recommended To Identify Those Who May Benefit from a Gluten-Free Diet
Based on these findings, experts recommend starting with a thorough medical history. If a patient has GI symptoms, such as abdominal pain or diarrhea, they should receive a referral to a GI specialist and undergo antibody testing.
In those with celiac disease, a GFD is required. (In celiac disease, gluten consumption can lead to severe inflammation of the GI tract.) In those without actual celiac disease, but rather with a blood test showing antibodies, a GFD may be recommended as a trial for 3 months.
There's certainly more research needed in this area. One important question is whether or not all patients with these antibodies will develop GI symptoms. In other words, should we be testing for antibodies even if patients have no GI symptoms? We need more research to answer that question.
Another important question is whether testing should cover other antibodies related to celiac disease and gluten. This is another question that requires further research.
The Healthy GFD and the Unhealthy GFD: The Need to Focus on Whole Foods and Limit Processed Foods
In any elimination diet, there are really two main areas to think about: what do you eliminate and, just as important, what should you eat?
In a GFD, you'll need to avoid wheat, barley, and rye. Patients with celiac disease are required to avoid gluten completely. To completely avoid gluten, you must read labels. Gluten may be used in many unexpected foods, especially processed foods where it may be used as an additive.
It's also important to recognize that there are healthy GFDs and there are unhealthy GFDs. One of my friends with celiac disease started a GFD. And then, slowly, she began to gain weight.
That's one of the downsides of a GFD. For example, a friend had switched from whole wheat foods to white rice. Whole wheat is a great source of several important nutrients, especially fiber and antioxidants. White rice doesn't provide those nutrients, because some of the important nutrients have been stripped away. The fiber that's found in whole foods is an especially important nutrient, and it's known to help limit weight gain because it helps us feel full. Since these nutrients are so important, I usually recommend consulting with a nutritionist, who can help patients identify other sources of fiber and nutrients. Choosing brown rice is another great alternative.
Many people who switch to a GFD find it challenging to find alternate healthy foods. They may find themselves relying on processed foods. Many gluten-free processed foods lack important nutrients, and some add in harmful levels of salt, sugar, and fat. This is an important pitfall of a GFD and one that you need to watch out for.
Which brings me to my most important point: A GFD diet may help some patients with psoriasis. But every single psoriasis patient, whether gluten-free or not, needs to be following one particular dietary pattern: a diet based on whole foods.
The Best Diet for Psoriasis (Gluten-Free or Not) Has a Strong Focus on Whole Foods
Every patient with psoriasis needs a diet that emphasizes whole foods and limits processed foods. That's because multiple research studies have now found that patients with psoriasis have a higher risk of high blood pressure, diabetes, and heart disease.
A diet that emphasizes whole foods can help limit the risk of these associated conditions. There are many to choose from: a number of different eating patterns focus on whole foods. Two of the best-known are the Mediterranean diet and the DASH diet.
The Mediterranean diet and DASH diets, respectively, have been shown to reduce the risk of heart disease and hypertension. They provide many other health benefits as well.
The Bottom Line: While some patients with psoriasis may benefit from a gluten-free diet, this applies only to a certain percentage of psoriasis patients. Since GFDs do have some potential downsides, experts recommend testing before you start a GFD. Experts also agree that the best diet for psoriasis (gluten-free or not) has a strong focus on whole foods.