nightshades and itching

Nightshades connection to pain, itching and digestion.

A couple months ago, I became viciously itchy. It started on my elbows, and then my knees and then to my thighs. Breaking skin itchy. Bouts of itching that would keep me from going to sleep. I couldn’t figure out why. I tried eliminating dairy, then gluten, and then sugar. Nothing seemed to make a difference.

I started to consider what could possibly affect the joints, since that is where it seemed to originate. It came to me: nightshades. I had always heard that nightshades could be an irritant to joints, but never did research past that knowledge that was handed down. I would often suggest that my patients with arthritic joint pain, try to eliminate nightshades from their diet to see if it made a difference in their symptoms. Given my recent experience, I began to research a bit more.

What is a nightshade? Nightshades belong to the Solanaceae plant family, which include over 2000 species of both edible and non-edible plants (morning glories and belladonna).

Common edible nightshades consist of:

• White potatoes
• Tomatoes
• Eggplant
• Peppers
• Okra
• Tomatillos
• Goji berries
• Paprika
• Cayenne pepper
• Tobacco
• Potato starch

I can now pinpoint back to a specific night when my symptoms began. I had eaten potatoes that night. And they were likely past their prime, with a few having some tiny eyes on them. That night, I recall be very itchy. And once I discovered that I had developed a sensitivity to nightshades, I could think back to times when I had eaten eggplant, tomatoes and potatoes and had horrible itching episodes. It was troubling because I thought I was doing well by eliminating gluten, dairy and sugar. But so freeing to finally know what it was.

Why would nightshades be a source of joint irritation? Nightshades contain alkaloids. Alkaloids are identified molecularly by a ring with a nitrogen atom and are derived from amino acids, purines or terpenes. Alkaloids to note in the nightshade family are: Solanine and Tomatine.

Solanine (primarily found in potatoes) and Tomatine (primarily found in tomatoes)
are known as a glycoalkaloid, a steroid alkaloid merged with sugar. When solanine begins to be metabolized by the body, sugar separates and the body is left with solanadine. Solanadine is not immediately toxic to the body after ingesting nightshade vegetables.  However, it can be stored in the body and may be released in times of stress.



Both of these steroid alkaloids are more concentrated in the green portions of the plants, much like chlorophyll. Potato leaves may not be on your plate, but what about those green spots of the new sprouts on the potatoes? Recall above, I had eaten potatoes that had just begun to sprout. Little did I know, I was getting a concentrated amount of solanadine in my system.

These steroidal alkaloids can irritate the gastrointestinal (GI) system and act as acetylcholinesterase inhibitors, which in turn affect neurotransmitters. This could show up as severe vomiting, diarrhea, central nervous system depression and even death—though these effects are rare.

Common reactions to nightshades can be similar to those experienced with other food sensitivities, such as gluten sensitivity. GI distress, heartburn, nerve sensitization and joint pain are commonly associated with nightshade vegetable sensitivity. And I would certainly add itching in there, after my recent experience.

nightshades and digestion

So if you have been experiencing symptoms that have not been resolved by eliminating gluten, dairy, sugar or other common food sensitivity culprits, then perhaps try eliminating nightshades. I would even suggest eliminating nightshades if you are experiencing persistent pain (joint, nerve or myofascial).

It should take about 3 months of elimination to notice changes. I will say for myself, that it has taken about 3-4 months, from the time I finally discovered that nightshades were the culprit. I also started taking a collagen powder supplement a month ago. And it was about a month ago that I did notice a shift when I could start to eat a little bit of salsa, tomato sauce and very small amounts of potato and did not experience itching. And it makes sense, as we know that the gut is affected by glycoalkaloids and that the gut can be healed by using collagen supplements. It is possible, as with other food sensitivities, that nightshade sensitivity can be alleviated by elimination, gut health improvement and then slow re-introduction of nightshades.


  1. Nightshades contain alkaloids that can become toxic to the body
  2. If you are experiencing persistent pain, eliminate nightshades for 3 months
  3. Also try adding collagen powder supplement, 1 scoop daily
  4. Slowly start integrating your favorite nightshade back in and watch for reproduction of symptoms. Stay to small amounts and don’t overdo. If you continue to have symptoms, then it may be a good idea to continue to eliminate them completely.

p.s. I get asked all the time why they are called nightshades. It seems unclear and there is no concensus on the meaning of the name. But I found this, “The name Solanaceae derives from the genus Solanum, “the nightshade plant”. The etymology of the Latin word is unclear. The name may come from a perceived resemblance of certain solanaceous flowers to the sun and its rays. At least one species of Solanum is known as the “sunberry”. Alternatively, the name could originate from the Latin verb solari, meaning “to soothe”, presumably referring to the soothing pharmacological properties of some of the psychoactive species of the family.”3

I welcome your feedback and if you find this information helpful, please share with your colleagues, friends and family. I would be interested in knowing if you have eliminated nightshades and found relief of your pain, GI distress or other symptoms.   Contact Tianna if you are searching for how you can create an integrative program, including diet and nutrition, specifically for your needs.

1. Boldt, E. (2017, November 04). What Are Nightshade Vegetables? Retrieved December 26, 2017, from
2. Cárdenas, P., Sonawane, P., Heinig, U., Bocobza, S., Burdman, S., & Aharoni, A. (2015). The bitter side of the nightshades: Genomics drives discovery in Solanaceae steroidal alkaloid metabolism. Phytochemistry, 113, 24-32. doi:10.1016/j.phytochem.2014.12.010
3. Solanaceae. (2017, December 25). Retrieved December 26, 2017, from

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