Psoriasis Diet - Tips on What to do for Psoriasis

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Psoriasis can be difficult to control. Although there are newer drugs available to treat moderate to severe psoriasis, many of these drugs compromise the immune system and have rather disturbing side effects. There is a way to improve psoriasis symptoms and reduce outbreaks. It is with diet. In particular, avoiding potatoes and tomatoes may greatly reduce outbreaks and symptoms.

Nightshade Family

Which plants belong to the nightshade family? Potatoes, tomatoes, eggplants, and the decorative herb, Bella Donna or Deadly Nightshade are members of this family.

All tomatoes - cherry, grape, slicing and heirloom are the same. It does not matter if they are grown organic or not. Tomatoes are members of the nightshade family.

Peppers - all peppers are members of the nightshade family. Serrano, jalapeño, poblano, sweet green, yellow and orange peppers, and Italian slicing peppers are all in this family. Black pepper, the kind sold as a spice, is not a nightshade member. This spice is okay for people with psoriasis.

White potatoes, yellow fingerlings, and blue potatoes belong to the nightshade family. Sweet potatoes and yams are an entirely different species and have no connection to nightshades.


Solanine is a strong glycol-alkaloid with narcotic properties. It occurs naturally in members of the nightshade family. This is why one should never eat the green parts of white potatoes or the stems and leaves of the tomato or potato plant. The leaves and stems have the highest concentration of this chemical. At one point solanine was used to treat epilepsy. Currently it is used in insecticides.

Why avoid potatoes and tomatoes? The answer is simple: solanine. Inflammation is one result of consuming solanine. There are many. It is thought that people who suffer from psoriasis may be hypersensitive to solanine. Psoriasis symptoms are aggravated by inflammation. This is one side effect of solanine. An overdose of this chemical can be fatal.

Potatoes and tomatoes contain large amounts of solanine. Although there are no peer reviewed studies of the connection of solanine and psoriasis, many people swear that eliminating these two products from their diet has helped to greatly reduce the symptoms and outbreaks of their psoriasis.

Where’s the Proof?

Although no studies have been published in peer reviewed journals linking solanine or members of the nightshade family to psoriasis outbreaks there is convincing evidence that such a link exists.

In the book “Your Healing Diet”, Deirdre Earls, MBA, RD, LD, explains the link between plants that contain solanine and psoriasis. She is convinced that since solanine is an inflammatory agent and psoriasis is aggravated by inflammation, then care should be taken to avoid foods attributed to inflammation.

There is no cure for psoriasis. Many people and physicians say it can be controlled by diet, however, there is tremendous disagreement as to what the ideal diet should be. With so much conflicting information, it is best to try a diet if it makes sense to you. Avoid miracle cures and diets that are too restricting. Try removing potato and tomato products from your diet and see if the psoriasis symptoms improve.


National Toxicology Program: alpha-Solanine