One of the common questions I get from people asks if nightshades are bad to eat when you have an autoimmune disease like psoriasis.

But before I get to the answer, let’s define what nightshades are first.

The nightshade family of plants or the Solanaceae family (pronounced sole ah NAY see ay) is a large, diverse set of plants from all over the world with nearly 3,000 species and found on every continent except Antarctica. Many are highly toxic to humans and animals in general, like the mandrake and belladonna, but a small set of them can be consumed by us.

What Are the Edible Nightshades?

  • Potatoes (but not sweet potatoes or yams)
  • Tomatoes
  • Tomatillos
  • Peppers
  • Eggplant

There are many spices that are derived from the nightshades as well: chili, cayenne, paprika, hot pepper flakes, and others.

Tobacco is also a nightshade, which I’ll get to in just a second.

What Is Psoriasis?

Psoriasis On a Man's Back and Trunk
The word psoriasis literally means itchy condition in Greek. Psoriasis is thought to be a hereditary disease that you get from one or the other (possibly both) parents. I got mine because my father had it, and before him, his mother did. You can’t get it from someone else – it’s NOT contagious at all.

It’s an autoimmune disease which means that your body attacks itself from the inside. There are many types of autoimmune diseases including psoriasis, vitiligo, alopecia, rheumatoid arthritis, celiac, multiple sclerosis, lupus and others.

In the case of psoriasis, the T cells (a type of white blood cell) attack a lower layer of the skin as if our skin was a foreign invader. This causes raised, red, itchy patches which can appear anywhere on the body.

Natural Poisons

The plants in the nightshade family produce a toxic alkaloid compound called solanine, which is the plant’s natural defense against getting eaten by animals or insects.

If you’ve ever heard that potatoes that have a green layer under the skin should be avoided, this is true. When exposed to light, potatoes can produce more solanine, which is toxic to humans (if consumed in a large enough dose).

Those of us with autoimmune diseases, such as psoriasis, are more sensitive to the naturally-occurring solanine in these plants, such as tomatoes, potatoes, eggplant and peppers. These types of foods can be “trigger foods” which cause our psoriasis to break out or get worse.

I’ve mentioned that my father had psoriasis, and I inherited it from him. Neither my sister, nor my brother have psoriasis. But what’s interesting (at least to me), is that my brother and I both HATE tomatoes. I’m not a huge fan of eating peppers, but I do like spicy foods. Similarly, my sister HATES peppers of all kinds, and so did my father. Clearly, our bodies are telling us not to eat these types of foods, even though neither of my siblings have psoriasis.

A recent study showed that those who ate fewer nightshades, saw improvement in their psoriasis.

Tomatoes and potatoes also produce a lectin that’s structurally and functionally very similar to gluten, and they may be just as inflammatory as wheat gluten. So even though you may be eating “gluten free” by avoiding wheat, potatoes may cause just as much inflammation as wheat based foods.

Tobacco is a Nightshade

We all know that smoking or using tobacco is bad for us. It causes lung cancer, cardiac issues and a host of other problems. It causes systemic inflammation in our bodies, so that our bodies are constantly in the red zone, when we need to be calming down any source of inflammation. What’s worse, is that tobacco is a nightshade, and for those of us with psoriasis, it causes your body to be flooded with the nightshade toxins on a constant basis, not just once in a while, like when we eat salsa.

Furthermore, nicotine is not only highly addictive, it’s toxic and has been used as a pesticide since the 1600s. Other plants in the nightshade family, like potatoes, tomatoes and eggplant, all produce nicotine as well, but at a much smaller level than tobacco. If you’re trying to quit, consuming those foods may make it more difficult for you.

If you use tobacco in any form, stop now. You have many options now to help you stop the addiction.

I get it! I smoked for 17 years (dumbest thing I ever did!), and quitting was one of the hardest things I’ve ever done. I quit smoking over 20 years ago, and at that time, we only had the patch. We didn’t have all the medications that can be prescribed to help break the habit. So work with your doctor now to get off the tobacco, and your skin (and heart and lungs) will thank you.