While fruits and veggies are universally lauded for their nutritional power, there’s one subcategory that sometimes gets a bad rap: nightshades. These plants, which include tomatoes, potatoes, eggplants, and peppers—as well as spices derived from them like cayenne pepper, chili powder, and paprika—may cause problems in people with autoimmune and inflammatory diseases including rheumatoid arthritis, leaky gut, lupus, irritable bowel disease, and ankylosing spondylitis. Less popular, but potentially problematic nightshades include goji berries, huckleberries, pepino melons, and tomatillos.
So why are nightshades problematic for some? It’s because they contain alkaloids, a nitrogen-containing compound found in small amounts in nightshades that acts as a defense against insects and mold. In foods like eggplants, potatoes, and sweet peppers, this alkaloid is solanine; in hot peppers, capsaicin; and in tomatoes, tomatine. In large amounts, these alkaloids are toxic to humans and animals, but for most people, these trace amounts are well-tolerated. Alkaloids are even used medicinally; capsaicin, which is what gives hot peppers their heat, is also a natural pain reliever.
While the “why” behind their negative effect on some people isn’t clear, there is evidence to suggest that they can disrupt the gut in people who have weakened immune systems or gut health problems. Symptoms associated with nightshade sensitivity include joint pain, migraines, fatigue, brain fog, acne, rashes, hives, and/or gastrointestinal problems like diarrhea, gas, and nausea.
Making Nightshades Work for You
Although nightshades don’t cause inflammation, they may exacerbate an existing inflammatory condition. If so, an elimination diet can be a great way to find out if nightshades are problematic for you. However, you may not need to rule them out forever. After an elimination diet you can begin a reintroduction phase to determine which nightshades, and in what amounts, aggravate your symptoms. Over time through repeated exposure, your tolerance may improve or return altogether, and if not, there are ways to prepare them that reduce their alkaloid content. And, if you’re like most people who can tolerate nightshades without issue, there are ways you can optimize their other amazing nutritional benefits.
TOMATOES
Tomatoes are a rich source of nutrients including vitamins A, C, and E as well as the antioxidant lycopene. Lycopene has been linked to sun protection, improved heart health, and even lowered cancer risk. The seeds and skin of tomatoes contain about half of their vitamin C and lycopene and pack a powerful lycopene punch when eaten raw. Even better, cooking them down into sauce actually triples their lycopene content.
• If you find that tomatoes are problematic for you, you can mitigate their alkaloids by removing the seeds and skin and pressure cooking or by cooking them down into sauce. You can also find lycopene, in much smaller amounts, in guava, watermelon, papaya, and grapefruit.
POTATOES
While foods like chips and French fries give potatoes a bad reputation, they’re actually quite nutritious. Not only are they a good source of vitamin C (containing nearly 30 percent of your recommended daily intake), but they also contain a quarter of your daily vitamin B6 and potassium, as well as smaller amounts of folate, manganese, magnesium, niacin, and phosphorous. They’re also rich in antioxidants, with colored varieties like purple containing three to four times more antioxidants than white. They even possess gut healing power: By cooking and cooling them, you can turn their starch into resistant starch which feeds the good bacteria in your gut—and prevents blood sugar spikes.
• If you find that potatoes are problematic for you, remove their skin, which will substantially reduce their alkaloid content. You should also avoid eating any potatoes that have turned green, as the color change signals an increase in alkaloids. And no matter your body’s tolerance of potatoes, you should aim to buy organic whenever you can, as conventionally grown potatoes are loaded with pesticides, fungicides, and sprout inhibitors. You can also swap regular potatoes for sweet potatoes or yams (which are NOT nightshades) or other root vegetables with a potato-like texture such as parsnips, turnips, rutabaga, or celeriac.
PEPPERS
Both sweet and hot peppers are loaded with nutrients and antioxidants, but sweet bell peppers are one of the most nutritious foods on the planet. Not only are they full of vitamin C, (three times your daily recommended intake at that), but they’re rich in potassium, vitamin B6, folic acid, vitamin A, and beta-carotene. Hot peppers are also rich in vitamin C as well as the alkaloid capsaicin, which as mentioned above, is an excellent natural pain reliever.
The benefits of sweet peppers are easy to optimize, as they make a great crunchy snack when eaten raw, can be roasted and added to salads or sandwiches, or sauteed in stir fry. Eating them raw nets you all of their vitamin C, but cooking them may increase their antioxidant power.
• If you find that peppers are problematic for you, try removing the seeds, or simply swap them for other crunchy raw vegetables like carrots, radishes, or celery. It should be noted, however, that like potatoes, both sweet and hot peppers grown conventionally are among the worst offenders as far as pesticide and insecticide residues are concerned, so be sure to buy them organic as much as you can.
EGGPLANTS
Eggplants are a wonderful source of fiber as well as anthocyanins and polyphenols, both powerful antioxidants. There are also over a dozen varieties, some of which may be easier on those with nightshade sensitivity. Eggplant skin is its most nutritious component, so thinner, more tender-skinned varieties like Japanese, Chinese, or graffiti may prove less provoking than others. Solanine gives eggplant its bitter taste, so sweeter varieties, including fairy tale and Italian, may be better tolerated as well. If no eggplant variety is well-tolerated, portobello mushrooms offer a similar texture when cooked, making them a great swap.
A Note on Non-Nightshade Alkaloids
While nightshades are the most common dietary source of alkaloids, there are some non-nightshade fruits and veggies that contain solanine, such as blueberries, artichokes, and okra. If you suspect a nightshade sensitivity, it may be worth including these on your elimination diet as well to see if they are triggering for you.
If you suffer from an autoimmune condition and want to better understand how nightshades might be affecting you, please contact me. Together we can make the elimination and reintroduction process easy, allowing you to enjoy the most diverse and nutritious diet your body deserves.