What Are 'Nightshades' and Should We Avoid Them?

What Are Nightshade Vegetables - Holisticole

The 'Nightshades' are a family of plants which have certain unfavourable characteristics in common. Nightshades are commonly a problematic foods, especially to those with an autoimmune disease such as rheumatoid arthritis, Addison's disease, type 1 diabetes, celiac disease and psoriatic arthritis.

There are over 2,000 species in the nightshade family, with over 200 different types of potatoes. But what makes nightshades 'dangerous' and why do some react to when they are consumed? 

This family of plants are actually poisonous with excessive consumption as they all have low-level toxic properties. The three main unfavourable components of the nightshade family are lectins, saponins and capsaicin (which I will explain further), but these factors are what make them such a common food sensitivity, and are also what makes them so problematic for those with an autoimmune disease.

Members of the Nightshade Family:

  • Paprika

  • Potatoes (not sweet potatoes) 

  • Tobacco

  • Tomatoes

  • Ashwaganda

  • Bell Peppers

  • Eggplant

  • Goji Berries

  • Hot Peppers (chili, jalapeños, habaneros, cayenne) 

3 Issues with nightshades


  • Also known as an “anti-nutrient” these are proteins that bind to sugar, they serve a purpose of protection for plants
  • All plants contain lectins, but not all lectins are harmful
  • Some lectins restrict digestion and can cross the intestine barrier to cause an immune response
  • Some lectins are pro-inflammatory and can promote leaky gut, others are completely harmless and potentially therapeutic
  • Lectins in the nightshade foods have more of a chance of becoming an issue within the body


  • Glycoalkaloids are a type of saponin found in nightshade foods
  • Saponins have a steroidal effect due to their adjuvant activity in the body which stimulates and exaggerates an immune response
  • These can cause flare ups and can aggravate and stimulate an autoimmune condition. 


  • This is a steroidal stimulant found in most peppers
  • Capsaicin is what provides the heat and spice in peppers
  • This is an irritant to cell membranes and because of this can increase intestinal permeability.


Do We Need to Avoid the Nightshades?

For someone with an autoimmune condition, leaky gut, or anyone with unresolved inflammation - I would highly recommend leaving these foods out of your diet. But for a healthy individual, I would still recommend you keep this information in mind. Strive for balance in everything. I wouldn't avoid these all together, just be mindful of consumption. 


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