Some wellness advocates express an aversion to nightshades—but, like many foods that are classified as "bad for us" or "good for us," there's little clarity on why. Because we love potatoes (and tomatoes and bell peppers and cayenne, oh my!), we decided to do some digging and get to the bottom of things.
But what actually are nightshades?
Nightshades actually reference the several thousand members that make up a species of plant called Solanaceae. While most of these aren't edible, several are, including tomatoes, potatoes, eggplants, bell peppers, and even some spices and herbs, like cayenne and chili pepper.
Why do some people think they're unhealthy?
That all comes down to the alkaloid content. Kimberly Snyder, best-selling author and mbg class instructor, explains, "Both the medicinal and the toxic aspects of nightshades can be attributed to their alkaloid properties. Mostly nitrogen-based chemical compounds, alkaloids have been found to have a wide range of pharmacological applications their purified form and have been used in everything from anti-malarial and anti-cancer drugs to stimulants, psychotropics, hallucinogens, and certain poisons. There are four basic types of alkaloids found in nightshade plants, but not all of them are present in those that we consider food staples. Steroid alkaloids are commonly found in most food nightshades including potato (solanine) and tomato (tomatine). Tropane, indole, and pyrrolizidine alkaloids are less common and known more for their druglike properties."
OK, but are they ACTUALLY unhealthy?
"I don't believe nightshades are bad for you," says Miranda Hammer, R.D. and founder of Crunchy Radish. "Green bell peppers, tomatoes, eggplant, and potatoes all have positive nutritional attributes and are real whole foods. A major reason why people avoid nightshades is the thought that they are pro-inflammatory. Nightshades aside, the real culprit of inflammation is refined and processed foods such as white bread, white rice, white pasta, and sugar, omega-6 fatty acids, and saturated and trans fats." Nightshades also contain a number of anti-inflammatory ingredients. "Tomatoes, which are considered part of the nightshade family, are full of antioxidants lycopene and vitamin C," Miranda says. "Lycopene intake has been linked to preventing heart disease, breast, and prostate cancer. Vitamin C is anti-inflammatory and also helps your body respond to stress."
Even if they do trigger inflammation, it might not be the nightshade's fault. Dr. Will Cole explains: "While nightshades contain alkaloids which can trigger inflammation in some people, it's not so much the foods fault as much as it is the person's gut and immune system that are compromised and imbalanced. For these people, I would recommend focusing on other healing foods and functional medicine protocols to heal the gut and balance the immune system so they can tolerate these nightshades, and benefit from their healthy properties."
Are there certain people who would be better off avoiding nightshades?
All of our experts pointed to one group of people who should avoid nightshades—people with arthritis. Because nightshades can be pro-inflammatory, for people with inflammation-specific conditions like arthritis, the negative elements might outweigh the positives. For everyone else, our experts recommend listening to your body. "I personally don’t have any problem digesting them, and I also don’t have RA, and so I enjoy them freely. I encourage you to do the same, and gauge your own body’s reactions as well," says Kimberly.