Monday Kitchen Tips: Fun with Nightshades

avoiding potato in your gluten-free diet if you're sensitive to nightshade plants

Totally gluten-free but still have unexplained achy joints or gut pain? Arthritis or fibromyalgia? Creaky joints? Autoimmune issues? It might just be your gluten-free baked goods, flour and other prepared products.

Take a look at the ingredients in your favorite products, especially the flours. Those pesky problems could be caused by nightshades and the most likely suspect is probably potato flour or starch.

There are so many tales of why the plants are called nightshades – that they grow in the shade of the night to ancient Romans using the berries and leaves to poison arrow tips or just the evening swig of wine they share with frenemies. But the real deal is that nightshades produce a chemical group of alkaloids and all of them can do bad stuff to people with sensitivities.

While the list of plants in the nightshade family is huge, the well known usual suspects include tobacco, tomatoes, eggplant, potato (anything not sweet potato or yam) and peppers. The entire list is included in the reference links at the bottom of the post.

Here’s what happened that made me take a closer look at those nightshade veggies.

My first homemade gluten-free flour mix (long ago)  included potato starch. But as my foot and hand arthritis flared to a daily thing it became clear that something was wrong. The arthritis turned up in my early 30’s but was rarely a daily thing until it was. Turns out the remedy was a simple solution but it took a long time to figure out that potatoes, a big part of our gluten-free diet, were making me gimpy. Seriously gimpy.

I went to lots of doctors and the only thing they could determine was that I had arthritis (big shock, not). My achy joints got injected with all kinds of medications which, if they worked at all, were ineffective after a few days. No one suggested looking at my diet. They only suggested I should be on a diet to lose weight because we all know that every single ailment is caused by being chubby.

When we avoided potatoes because we were on a low carb kick, or just sick of eating them, I usually started to feel pretty good and my feet were no longer achy, my thumbs stopped being stumps and the claw went away.

Eliminating potatoes is not an easy thing to do. Potatoes are everywhere – almost as much as corn is in everything. Some baking powders contain potato starch. Lots of gluten-free prepared foods contain potato in some form.

While the alkaloids in nightshades can be a problem for those sensitive to them, for others who have mild symptoms, try cooking them thoroughly. The alkaloid content is almost cut in half when the nightshades are cooked (see resources below).

If I eat eggplant or even bell peppers every once in a long while, I’m usually ok. But if I push it and eat those foods too frequently, it becomes a tipping point and the results can be pretty awful. One nightshade food sensitivity does not necessarily mean that the rest of them are equally evil.

Get to know your own personal nightshade tolerance.

The best way to know if you react to nightshades is to eliminate them from your diet for a number of weeks. Then add them back one at a time and assess the results. That’s how I determined that potatoes are my nemesis but peppers, tomatoes and eggplant are less a pain (pun!) when eaten infrequently.

Fun with nightshades, not so much. Whether an ancient Roman with frenemies to poison, or just trying to feel as good as you can, think about leaving the nightshades (or the Potato Head family) off your to-do list.


Nightshade List from Wisegeek

ThePaleoMom talks about nightshades 

Norman Childers talks about Nightshades

About glycoalkaloids produced by nightshades


  1. robina gaines says:

    Great info thank-you!

  2. Thanks for sharing this info with the community. Personally, my nightshade problems started with tomatoes, worked up to to bell peppers and white potatoes and goes on. That stuff was in everything I ate! The reason I love this post so much is that almost everyone uses potato starch in their GF mixes, other than you and I apparently. It’s something for folks to think about like the fact that according to some sources up to 50% of those with gluten issues also cannot process casein and they have no clue. No one has suggested that after giving up gluten they should also try two week without dairy. Gotta love our up to date medical profession. Sigh.

    • GlutenFreeCanteen says:

      Thanks, Laurel. You’re right – casein and whey can be issues right along with nightshades (and corn).