Get full access to Outside Learn, our online education hub featuring in-depth nutrition, fitness and adventure courses, and more than 2,000 instructional videos when you sign up for Outside+..
Q: I’ve heard the term “nightshade foods,” but I don’t know what foods those are. I’ve also heard that some people avoid them. Why? —Maria G., Yuma, Ariz.
A: Nightshades are the common name for flowering plants that belong to the botanical family Solanaceae, which contains more than 2,000 different species. Many nightshades are poisonous and should never be eaten, including belladonna, also known as deadly nightshade.
Many nightshades, however, are very popular foods—tomatoes, potatoes, eggplant, all types of sweet and hot peppers, cayenne, chili powder, paprika, pimentos, tomatillos, chilies, goji berries, and ashwagandha (an adaptogenic herb used in Ayurvedic medicine). In fact, in the U.S., we consume almost 230 pounds of nightshades per person per year.
Did You Know? The nightshade belladonna was used by Macbeth to poison invading Danish troops.
Nightshades and Arthritis: Personal Stories, Limited Research
Though many health professionals encourage people to eat these foods, herbs, and spices for the nutrients they provide, some people strictly avoid nightshades. To be clear, no scientific research in humans has ever looked into the long-term health effects of eating nightshades. But evidence based on personal reports and the experience of nutritionists and integrative health specialists suggest that eating nightshades is connected with arthritis and joint pain, and that eliminating them from the diet is extremely helpful and sometimes a dramatic answer for overcoming joint pain.
One of those personal stories comes from Sherry A. Rogers, MD, a general practitioner and author of numerous books on health. In a testimonial on the Arthritis Nightshades Research Foundation website, she writes that she had such severe incapacitating joint pain from nightshade foods that she could barely walk or use her hands. She tried every known medicine and top specialist, and says she would likely be a drug addict or in a wheelchair by now if she hadn’t learned about the tremendous healing power of a nightshade-free diet. “It’s right up there with the best ways to heal the impossible,” she says.
Others have reported relief from autoimmune diseases allergies, asthma, and heartburn and other digestive issues.
According to Loren Cordain, PhD, author of The Paleo Diet, nightshade plants contain toxic substances (such as glycoalkaloids and lectins) that increase intestinal permeability, or “leaky gut.” A leaky gut is believed to set off an autoimmune reaction when various proteins (which should stay inside the digestive tract) make their way out into the bloodstream, and the body attacks them in response. In one study, researchers fed potato skins (where most of the glycoalkaloids lurk) to mice with inflammatory bowel disease, and found that gut inflammation was significantly increased.
Should you avoid eating nightshades?
So, should you avoid eating nightshades? No one really knows for sure, as our understanding of this topic is still in its infancy.
Many practitioners who are aware of ill health effects from nightshades say that the foods are a problem only for people who are sensitive or allergic to nightshades. Other practitioners, such as Garrett Smith, ND, from Tucson, Ariz., believe that while individual differences make some people feel worse after eating nightshades than others, toxic substances in nightshades are a problem for everybody over time—and the more nightshades that people eat, the worse their health issues are or will become.
Let’s say you have salsa on your eggs at breakfast, an eggplant dish at lunch, pepper strips with a dip for a snack, and a baked potato with dinner. Although many people seem to do fine eating this way, doing so could lead to an overload of glycoalkaloids and lectins that might contribute to a variety of health issues over time.
The Six-Week Nightshade Diet Challenge
If you’re curious to find out whether or not nightshades adversely affect you, try taking a complete break from consuming all nightshades in your diet for at least six weeks, and see how you feel. This is particularly advised if you suffer from an autoimmune disease, a chronic inflammatory condition, gastrointestinal problems, arthritis, or any other type of pain.
If you don’t seem to have trouble with nightshades, it’s still good to err on the side of caution. Make a few of your meals each week nightshade-free, and vary your diet to incorporate other foods.
If you find that nightshades increase your pain or cause other uncomfortable symptoms, fear not: There are tasty ways to avoid common nightshade foods. New England Patriots quarterback Tom Brady and his family reportedly steer clear of nightshades. If they can do it, you can do it too.
Nightshade Vegetable Substitutes
No more mashed potatoes, salsa, or pizza? At first, the thought of avoiding nightshade foods seems impossible—or, at least, inconvenient—but improved health and less pain are powerful motivators to going nightshade-free. Try the following alternatives to five popular nightshade foods.
In place of: White Potatoes (in a recipe).
Try: Parsnips or sweet potatoes.
In place of: Mashed Potatoes.
Try: Mashed cauliflower.
In place of: Chili pepper.
Try: Wasabi, horseradish, mustard powder, cumin, ginger, or freshly ground black peppercorns.
In place of: Salsa.
Try: Make a mango-pineapple salsa with red onion, garlic, and cilantro; or make a salsa with blended cooked carrots and beets, onion, and lime juice.
In place of: Tomato-based pizza sauce.
Try: Basil pesto sauce; or make a sauce out of cooked mashed carrots, beets, and onions with herbs.