Researchers are exploring how diet and food allergies can affect psoriatic arthritis and psoriasis.

About 8 million people in the United States are living with psoriasis. Of those, about 30% will develop psoriatic arthritis. The two conditions make up what is generally referred to as psoriatic disease.

Psoriatic arthritis is more than just swollen joints and pain. It involves widespread inflammation throughout the body. Inflammation can have a negative effect on several aspects of health and is linked with an increased risk of obesity and heart disease.

People living with psoriatic arthritis often look for ways to stop inflammation from occurring. One of the areas researchers and others are exploring is how diet and food allergies can affect psoriatic arthritis and psoriasis.

This article answers many questions about food allergies and diet and how it affects psoriatic arthritis.

The foods a person eats can affect their psoriatic arthritis symptoms. According to an older study published in 2012, food allergies may contribute to the inflammation associated with the disease.

They noted that a type of antibody, immunoglobulin G (IgG), contributes to hyperpermeability. This means the intestines allow more than just water and nutrients to pass through. IgG also plays a role in the body’s inflammatory response.

By removing certain foods from the diet, a person may be able to help reduce their psoriatic arthritis symptoms.

According to a 2022 study, the top seven IgG foods include:

  • eggs
  • crab
  • milk
  • corn
  • tomatoes
  • mushrooms
  • shrimp

Finally, the 2012 study also noted that celiac disease and psoriatic arthritis share a link. They share similar inflammatory features. A person with celiac disease should follow their diet recommendations, which may help with their psoriatic arthritis.

Psoriatic arthritis may not directly affect or cause issues with the digestive system, but certain conditions share a common link with psoriatic arthritis.

In a 2018 review, researchers linked psoriatic arthritis to Crohn’s disease but not ulcerative colitis.

Other studies point to genetic similarities and shared inflammation pathways in psoriatic arthritis and inflammatory bowel disease (IBD), particularly Crohn’s disease. A 2019 study suggests that people with these conditions have lower levels of beneficial bacteria in their body.

In other words, caring for the gut may help with both IBD and psoriatic disease.

Everyone reacts differently to the foods they eat. There is currently no specific diet that will cure psoriatic arthritis, but some foods may help.

Some people have specific food allergies, such as dairy. If dairy is an issue, a person should avoid milk, cheese, and other dairy products. These may both aggravate their intolerance or allergy as well as possibly increase inflammation in their body.

A person who does not have lactose intolerance or an allergy to milk may find that keeping low fat dairy in their diet is helpful.

Other foods a person should avoid include:

  • Red meats: A 2017 study noted that consuming large amounts of red meat was associated with a higher body mass index (BMI), which can make psoriatic arthritis symptoms worse.
  • Processed foods: Processed foods contain a large amount of sugars, fats, and salt. A 2022 study noted that highly processed foods have a positive association with IBD, which shares a link with psoriasis and psoriatic arthritis.

No diet can cure conditions like psoriatic arthritis. However, making changes to a diet may help in some cases.

The National Psoriasis Foundation notes that psoriatic arthritis goes beyond the joints. It is a systemic inflammatory condition, meaning inflammation can affect the whole body. This can make a person more susceptible to other conditions, such as heart disease.

They also note that taking steps to reduce inflammation may help. For some, an anti-inflammatory diet may help. They do not promote any specific diet, but they recommend a person achieve a balance of lean proteins, carbohydrates, and fats from foods such as:

  • fish
  • avocados
  • fruits
  • vegetables
  • beans
  • nuts
  • leafy greens
  • olive oil

Following a healthful diet may help reduce some people’s psoriatic symptoms. It may also help improve a person’s overall health and help them manage their weight.

Dairy can be helpful for some people living with psoriasis. According to a 2020 study, people with psoriasis often have a vitamin D deficiency. They noted that vitamin D plays a role in regulating inflammation, which makes it a helpful nutrient for conditions like psoriasis.

The National Psoriasis Foundation also says adding more vitamin D may be helpful. However, they note that studies on vitamin D’s effect on psoriasis are limited and too much vitamin D can be harmful. They recommend speaking to a nutritionist before adding vitamin D to the diet.

People interested in adding more vitamin D may find dairy, like milk or cheese, helpful.

However, a person with lactose intolerance should avoid milk and other dairy products. These can cause digestive issues as well as potentially make psoriasis symptoms worse.