This article is the first in our series of requested topics from our subscribers: Psoriasis and diet. A number of you requested an article about daily activities or approaches to life with skin disease. In this particular post, we will investigate dietary factors. Many patients with skin conditions are concerned that dietary factors are strongly correlated to their diseases. For example, some patients believe that consuming sugar or milk can flare up acne. Others believe that eating products high in gluten such as bread can also trigger a flare up of a scaly, itchy, and flaky rash. Today, we will focus on psoriasis and specifically how diet, gluten sensitivity, and supplements play a role in the disease. We will try to answer the following questions: Does diet does affect psoriasis? What should I be eating? What should I avoid eating? Should I take any over-the-counter supplements?
There is no doubt that your health is linked to dietary habits. For example, in the United States, we typically consume what is described as a “western diet” when compared to other cultures around the world. The western diet typically contains high-calorie foods, added sugars, saturated fat, and red meat which may cause weight gain if not balanced with exercise. Weight gain, we you will read in our next section, can make psoriasis worse. So, if the a diet that causes weight gain should be avoided, which diet is best? Well, a Mediterranean diet is a good place to begin. Generally speaking, this diet is mainly plant-based, low in processed foods, low in sugar, high in whole foods, nuts, olive oil, and lean meats such as fish. A diet made up of whole food including fruits, vegetables including tomatoes, carrots, green leafy vegetables such as broccoli, spinach, and lean meat all contain antioxidants has been shown to be protective against psoriasis. Specifically, individual small molecular components of these healthy foods have been shown to improve the inflammation associated with psoriasis.1
Multiple studies have concluded that obesity plays a major role in psoriasis. Patients with a higher body mass index (a measure a body fat) usually have more severe psoriasis. Also, being obese increases your risk of psoriasis twice as much as someone with a normal weight.2,3 Additionally, once you have psoriasis, it tends to be more difficult to treat and clear the skin. A higher drug dose is sometimes needed for overweight patients as their psoriasis especially in patients who take biologic drugs.4,5 So, does losing weight make your skin more easily treated? The answer is yes. Patients at a healthy normal weight usually to respond better to treatment.6,7
Gluten is a common component of many foods and includes wheat, rye, and barley. It is a small particle that is essentially tasteless and is difficult to completely avoid without a very strict diet. The most common gluten-containing foods include bread, beer, cereals, gravy, salad dressings, soups, and beer. Gluten is in so many different foods and even very small amounts can cause problems. Interestingly, oats (although still a grain) are safe to eat as long are they are certified gluten-free and not contaminated with trace amount of gluten during processing.
The short answer is maybe. Celiac disease is an autoimmune disease triggered by exposure to gluten. Because psoraisis is associated with other autoimmune diseases including Celiac disease, some scientists have investigated whether patients with psoraisis may be at risk for Celiac disease. The risk of Celiac disease in psoriasis patients is higher than the general population but overall extremely low at less than 0.5%. Additional studies have also shown that a small subset of psoriasis patients have the immune-stimulating proteins (antibodies) to gluten similar to patients with Celiac disease.8 Although some studies have not definitively shown that avoidance of gluten will improve the skin, others have demonstrated improvement of psoriasis with a gluten free diet after 3 months of avoidance.9
This is another common question we hear. What evidence, if any, exists to recommend patients take fish oil supplements and can they help? Usually, patients are already using prescribed medications such as topical steroids, phototherapy, or systemic medications, are not at their skin goals, and do not wish to change their prescription treatment. The most common supplement for psoriasis is an omega-3 fatty acid such as fish oil. Alternatively, a diet consisting of regular consumption of oily fish such a salmon can be used instead of supplements. Does science support this recommendation? Well, it has been studied extensively without clear benefit . To begin with, the typical dose of fish oil required is quite high since three one gram capsules (a common dose of fish oil) is required. This is because most studies used an average of three grams. This was quite variable and some studies used up to 12 grams.10 So, should you take fish oil? A few of these smaller observational studies have shown improvement while many of the well-done studies have not.11 Suffice it to say that the jury is still out on whether a diet heavy in fish or omega-3 fatty acid supplements improve psoriasis.
So then, what supplement is best for psoriasis? Well, one supplement that is essential, as most members of the modern world are deficient, is vitamin D. The recommended daily amount of vitamin D is 400 international units (IU) for children up to age 12 months, 600 IU for ages 1 to 70 years, and 800 IU for people over 70 years. In general, patients with psoriasis are more likely to be vitamin D deficient when compared to the general population so supplementation is generally recommended when treating psoriasis and scalp psoriasis.12 Taking additional vitamin D at higher doses has not yet been shown to improve psoriasis.13 Extensive exposure to the sun, although can improve psoriasis, is typically not recommended since it can increase the risk of skin cancer. Additionally, only about 50% of people that live in sunny locations such as Hawaii do create enough their own vitamin D even with regular sun exposure.14 Therefore, dietary intake is essential. Furthermore, many internet sources reference supplements that could help psoriasis which is possible but not founded upon scientific research. Just a few vitamins, cobalamin (also known as vitamin B12) and selenium, have been studied and not been shown to improve psoriasis.
Diet and psoriasis symptoms are linked in ways as we outlined above. Whether these interventions translate into improvement of scalp psoriasis, sebopsoriasis, dandruff, or a dry, flaky, itchy scalp is unknown as these conditions were not studied exclusively. That being said, why not try them and see if it works for you? A healthy diet which includes lean meats and is rich in fruits and vegetables, regular exercise, and vitamin D supplementation is recommended to maintain a healthy body. You can take steps on your own to potentially improve your skin that does not require a prescription or visit to a doctor’s office.