What’s a nightshade? It’s one of those strange English words that’s not what it seems. Though it sounds like a special type of night light, it’s actually a botanical name. Nightshades belong to a family of flowering plants that includes various vines, shrubs, trees, and weeds. Though the origin of the word isn’t entirely clear, it may come from people who believed these plants only grew at night, or undercover of shade. Somehow, the name stuck, and the nightshade family now includes around 2,700 species of plants.
Of course, most of us don’t need to be concerned with all 2,700 varieties of nightshades. Instead, the relevant ones include those we eat, like fruits and vegetables. These include: potatoes, tomatoes, numerous types of peppers, and eggplant. (Though plenty of other edible nightshades exist, they’re not as common in a Western diet.) This handful of foods boasts some powerful nutrition and health benefits.
Recently, however, a firestorm around them has ignited. Some believe nightshades actually cause, rather than improve, health issues. And we’re not gonna lie—throughout history nightshades have proven lethal due to a small subset of specific varieties.
So, let’s get to the bottom of what’s true and what’s false about nightshades. What do these plants really have to offer, and should you stay away?
Nightshades and Inflammation
First, let’s address the elephant in the nutritional room: the controversy around nightshades and inflammation. If you suffer from an autoimmune or other inflammatory condition and have done any Googling on dietary methods of treatment, you may have come across information stating that nightshades contribute to inflammation. Football star Tom Brady’s personal chef has famously said that the celebrity athlete and his supermodel wife avoid nightshades for this reason. Numerous websites go bold with claims that removing them from the diet can improve, or even cure, arthritis and other inflammatory conditions (1).
According to the anti-nightshade crowd of bloggers and internet health gurus, this family of plants contains a chemical called solanine. This chemical is thought to aggravate inflammation, thereby worsening symptoms like joint pain, swelling, and tenderness.
But bloggers and celebrity chefs really aren’t the best sources of solid information when it comes to your health. Respected authorities on the subject, such as the Arthritis Foundation and Medical News Today, have debunked the idea of a connection between nightshades and inflammation, citing lack of scientific evidence (2). The Arthritis Foundation goes so far as to tackle the nightshades-for-arthritis theory with the definitive statement: “No research backs this claim” (3). If anything, it appears that eating certain nightshades may actually improve some measures of inflammation. A 2010 study in the Journal of Nutrition found that subjects who ate yellow and purple potatoes (both nightshades) regularly for six weeks ended up with lower blood markers of inflammation and DNA damage (4).
What About Deadly Nightshades?
Nightshades don’t cause inflammation…but that good news pales in comparison to the question of whether they could actually kill you. There’s a reason Marvel comics came up with an evil she-villain named “Deadly Nightshade.” Some members of the nightshade family are known to be toxic. (Sounds kind of like most of our families, no?) The most notable name… “deadly nightshade,” also called belladonna. This perennial herb with disarmingly attractive berries has a long history of use as an anesthetic, recreational drug, and—yes—a poison. Its effects have been described as “unpredictable,” ranging from delirium and hallucinations, to death.
Thankfully, unless you like to forage for your dinner in the forests, you’re not likely to encounter this poisonous plant in your food supply. Rest assured, there’s nothing lethal in your tomatoes, potatoes, peppers, and eggplant.
Health Benefits of Nightshades
With those potential impediments to eating nightshades out of the way, let’s take a look at their many health benefits.
Hands-down, potatoes are the most widely consumed of all nightshades—and perhaps the most often maligned (5). Many people believe white potatoes=bad carbs, but this isn’t necessarily accurate. It’s usually the unhealthy preparations: fried, mashed with gobs of butter, etc. and not the starch/carbs at all. Underneath it all, potatoes contain plenty of important nutrients. They’re high in fiber, which helps regulate digestion. They also pack a hefty doe of potassium, a mineral that’s useful for controlling blood pressure (6).
Perhaps the reason potatoes and tomatoes go well together (think French fries and ketchup) is that they’re actually related. After potatoes, tomatoes are most common nightshade in the American diet. While we may never solve the age-old debate as to whether they’re a fruit or a vegetable, we do know that tomatoes are an excellent food to eat regularly for all their positive health effects.
Tomatoes contain a unique chemical compound called lycopene. This carotenoid (aka food pigment) not only gives tomatoes their signature red color, it has antioxidant effects that have been associated with reduced risk of heart disease, narrowing of the arteries, and breast and prostate cancer (7, 8). In addition to health-promoting lycopene, tomatoes contain a significant amount of vitamins A, C, and K, all critical components of a healthy diet.
Red, yellow, green, or chili? You choose since all of these nightshade peppers come with an impeccable nutrition profile. Bell peppers contain Vitamins A and C in abundance, along with a respectable amount of folate, an important vitamin for pregnant women. Red peppers tend to have the highest concentration of these nutrients since they’ve stayed on the vine longest.
Intriguingly, contrary to the pro-inflammation hypothesis about nightshades, a compound in chili peppers, called capsaicin, has been shown to decrease pain and inflammation in arthritis and other conditions (9).
Eggplant seems to be one of those foods people either love or hate—but if you love it, you’re in luck. This oblong purple veggie packs a sizable punch of fiber. Similar to its tomato cousin, it contains a unique antioxidant all its own called nasunin. Found in eggplant’s purple pigment, nasunin combats harmful free-radicals that cause cellular damage (10). Plus, with a high percentage of water, eggplant is remarkably low in calories (just 20 per cup!).
Nightshades all Day
It’s always a good idea to eat more vegetables. Nightshades make an excellent addition at mealtimes for their vitamins, minerals, fiber, and antioxidants. If you tolerate them well, you can enjoy eating them as a regular part of a healthy diet.
To find out how YOU tolerate nightshade vegetables, check out the 131 Method.