Tomatoes and Psoriasis: is The Nightshade Theory True?

Psoriasis is a chronic condition with no known cure. It’s caused by improper functioning of your immune system. The condition makes new skin cells develop unnecessarily on top of your existing, healthy skin. The resulting patches can appear anywhere on the body, but most often affect the skin at the elbows, knees, scalp, fingernails, and toenails. Psoriasis can also generate joint inflammation, which is known as psoriatic arthritis.

The extra skin cells group together in gray, itchy, and even painful patches that can crack and bleed. Though it’s a chronic condition, the harshest symptoms aren’t always present and noticeable. Symptoms can come and go for different periods of time. Patches can also shift in size and appear in different places than they did during prior outbreaks.

Are tomatoes forbidden?

Stories have circulated that eating nightshade fruits and vegetables — those derived from the plant family Solanaceae — can trigger flare-ups of psoriasis. Nightshade fruits and vegetables include tomatoes as well as white potatoes, eggplants, and pepper-derived foods like paprika and cayenne pepper (but not black pepper, which comes from a different plant altogether).

The evidence that avoiding nightshades can help prevent psoriasis is anecdotal. Scientific studies have yet to show a clear connection between eating nightshades and worsening outbreaks. If tomatoes or other nightshades seem to make your condition worse, eliminate them one by one, and keep a food diary to note changes.

Alternatives to tomatoes

Tomatoes are a good source of many important nutrients. They are rich in vitamin A and potassium and can also provide vitamin C and calcium. If you’re going to remove them from your diet, consider other sources for the nutrients they provide.

Vitamin A

Vitamin A supports eyes and skin. You can also find vitamin A in dried apricots, cantaloupe, carrots, leafy greens, liver, mangos, squash, and sweet potatoes (which are not part of the nightshade family).

Vitamin C

Vitamin C helps cells grow and helps us heal. It’s abundant in many fruits, including cantaloupe, citrus fruits and their juices, kiwi, mango, papaya, pineapple, strawberries, raspberries, blueberries, cranberries, and even sweet watermelon.


Potassium is an electrolyte that is required for healthy blood pressure and smooth muscle function of the digestive tract and muscles. Potassium is found in bananas, avocados, beans, sweet potatoes, and dark leafy greens.


This mineral keeps bones strong, and also helps regulate blood pressure. Popular sources of it include dairy products, small fish with bones, collard greens, soy, and cooked beans.

What triggers flare-ups?

While psoriasis is an inherited condition, certain behaviors and life conditions can make it worse. These include smoking cigarettes and being overweight. Psoriasis flare-ups can also be triggered by direct skin contact with known irritants, like poison ivy or sun exposure.

Drinking a large quantity of alcohol (greater than one drink a day for women and two for men) and experiencing great levels of stress can also act as triggers.

It can be challenging to identify your unique triggers as well as to discover treatments that are effective for them.

Outbreaks can cause feelings of self-consciousness, given the effects they have on appearance. These challenges can be frustrating and may lead to psychological issues, such as anxiety and depression, which can also hamper social and work activities.

What can you do about them?

Medications are available that can restrict inflammation, intervene successfully with immune system malfunction, or stop unwanted cellular growth. Ultraviolet light therapy, when properly supervised by a physician (lay off the tanning beds), can improve the condition. Many people use moisturizers that make the surface of their skin feel better.

Although there is no cure yet for psoriasis, many of its symptoms can be addressed. Many people have been able to reduce the intensity of an attack, or limit the number of attacks, by consuming or eliminating particular foods. The specifics for this kind of method are difficult for medical specialists to track and confirm. If eliminating some things from your diet improves your psoriasis, then stick with that diet. Many experts agree that a diet of vegetables, fruits, lean proteins, and whole grains almost always has a positive health impact.

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