1.    Wheat

We’ve all seen or heard something about gluten. But most of us don’t know what it is. Gluten is a protein found in common foods, like wheat products. And it may play a part in the development of psoriasis.

According to Everyday Health, the relationship between psoriasis and gluten isn’t clear. However, some link celiac disease to an elevated risk of psoriasis.

That said, experts warn that this is just a theory. “While some skin conditions are worsened by wheat, no scientific studies support a gluten-free diet for psoriasis,” Dr. Paul Yamauchi tells Everyday Health.

2.    Alcohol

There may be a link between alcohol consumption and psoriasis. According to Healthline, a study conducted in 2010 concluded that those with this health condition drink more. And another study found that the incidence of psoriasis was elevated in subjects who drank non-"light" beer two or three times a week.

The National Psoriasis Foundation has offered some guidance on this concept. They suggest limiting alcohol. And in the case of severe psoriasis, it may be prudent to cut out alcohol altogether.

3.    Tomatoes

We’ve all heard that nutrient-rich tomatoes are good for us. But for those with psoriasis, the opposite may be true.

According to ABC News, tomatoes are considered “nightshade vegetables.” And it is thought that nightshade vegetables may affect certain people with this condition. That said, ABC News warns that there is no scientific research to back up this belief. The only way to tell is to experiment with eliminating nightshade vegetables from the diet.