Key Topic

Nightshade vegetables, including tomatoes, potatoes, eggplants, and peppers, often spark debate in the nutrition world. A common question, especially in relation to autoimmune conditions, is whether these vegetables should be avoided due to potential negative effects. While some claim that nightshades contribute to inflammation or digestive issues, others argue they are a nutritious and beneficial part of a balanced diet. In this episode, we break down the evidence behind these claims and help you determine whether avoiding nightshades is necessary for your health.

What Are Nightshades?

  • Nightshade vegetables are a group of vegetables from a specific family of plants. Some of these plants are not considered edible, while others are. 
  • All nightshades contain alkaloids. 
  • One of these is solanine, which is something that is toxic when consumed in large amounts.
  • Common examples of nightshade vegetables people consume are potato, eggplant, tomato and capsicum.

Why Is It Proposed That We Should Avoid Them?

  • The reasons people propose avoiding them typically link back to components such as solanine.
  • People often talk about how they can contribute to inflammation and joint pain.
  • They are proposed to contribute to leaky gut as well. 
  • Autoimmune conditions in particular are often anecdotally linked with nightshades.
  • Some nuanced views also propose that this isn’t relevant for everybody. Some people propose that it is just relevant for people with intolerances or allergies to nightshades. 

Identifying Flaws in That Thinking

  • Mechanistically we can look at some of that stuff.
  • Solanine does not appear to be harmful at a population level when consumed in normal amounts.
  • For example, regular potatoes contain solanine, but the amount is typically insignificant. But if a potato is green or a tomato is unripe, it can contain a lot more. 
  • In many cases people can get GI issues from eating these in large amounts, although there are multiple variables in play.
  • At a population level these vegetables don’t appear to be linked with inflammation. 

Specific Conditions

  • Some animal and lab-based research suggests a potential link between nightshade vegetables and inflammation in conditions like inflammatory bowel disease and rheumatoid arthritis. However, there is limited human evidence, making it difficult to draw strong conclusions.
  • The autoimmune protocol diet removes nightshades.
  • We’ve spoken about the diet back in episode 118 and have added a bunch of research in the links below.
  • The short version is that on average the limited research has found modest improvements in autoimmune conditions. But we also often see improvements when there are improvements in nutritional quality anyway AND in many cases there was a bit of buy-in added through having people read books on the subject etc.
  • Part of the reason for mentioning that research even though it isn’t on nightshades is it gives an insight that this isn’t necessarily a simple solution for a large percentage of people with autoimmune conditions.

Should Anybody Eliminate Them?

  • Everything we have spoken about has been at a population level while also acknowledging that the levels of a lot of these compounds are quite low in normal consumption.
  • But there is still a possibility at an individual level that you could find issues consuming them.
  • It’s not an approach I typically recommend but our thoughts are that it can be simple to test. You just eliminate them for a few weeks and see if it helps. It’s possible to have a great diet without them, so if you have to or want to remove them from your diet, it isn’t a huge deal.
  • If doing that – I’d also consider trial and error over time where you try to re-introduce them at various intervals. 
  • Anecdotally some people have found certain ones seem to be bigger triggers for them. So even if it happened to be relevant, it is worth exploring.

Summary:

  • At a population level, nightshade vegetables are not an issue. Typically they are beneficial addition to most diets.
  • At an individual level it’s still a possibility that they might be a factor for you and it is worth doing a bit of trial and error if you think it’s a factor for you.

Relevant Blogs/Research

Relevant Studies:

Relevant Podcasts: