Nightshades and inflammatory bowel disease (IBD)

When you have inflammatory bowel disease (IBD) knowing what foods and drink affect your symptoms can be a bit of a minefield.

Some people with IBD have reported that nightshades can cause a negative effect on their symptoms. Here we take a look at some of the reasons why that may be to help you make your own decision about whether it may be having an effect on your symptoms.

What are nightshades?

Nightshades are fruits and vegetables which belong to the family of Solanaceae plants of the Solanum genus. There are over 2,000 species and they include:

  • Potatoes (not sweet potatoes)
  • Tomatoes
  • Peppers (bell peppers, chili peppers, paprika, tamales, tomatillos, pimentos, cayenne)
  • Aubergine (eggplant)
  • Okra
  • Ground cherries
  • Goji berries

They come from the same family as deadly plants like belladonna, mandrake and datura.


Problems with nightshades

Nightshades contain high levels of certain alkaloids. These naturally occur in many animals and plants and in plants act as a natural pesticide.

Some people are sensitive to the alkaloids found in nightshades.

Alkaloids in nightshades have been linked to stopping the work of the enzyme cholintesterase in our nerve cells and are thought to cause inflammation in joints and calcium loss from our bones. They can also irritate the gut.

Nightshades and IBD

There have been a limited amount of studies done in relation to the effect nightshades can have on the human body. One of these studies has shown that potato glycoalkaloids can aggravate IBD1.

They are also thought to be an inflammatory food and trigger an immune response - which could aggravate your IBD.

Should I avoid nightshades?

Some people choose to cut nightshades out of their diet for a while to see if they feel any different. This is a personal choice. If you do decide to do this you should make sure you are still eating a balanced diet which includes other fruits and vegetables.


  1. Patel B, Schutte R, Sporns P, Doyle J, Jewel L, Fedorak RN. Potato glycoalkaloids adversely affect intestinal permeability and aggravate inflammatory bowel disease. Inflamm Bowel Dis. 2002 Sep;8(5):340-6. PMID: 12479649


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