Shady Veggies

Nightshades can induce inflammation, pain in some people

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Some nightshades commonly consumed by humans contain compounds that can trigger inflammation and joint pain.

Health derived from home gardening is second only to superior flavors.


When a garden’s balance tips toward nightshades — tomatoes, peppers, potatoes and eggplants — the health consequences can outweigh the benefits. “Most of them are really disappointed,” says Lisa Newton, nutritionist and health coach at Rosa Transformational Health in Medford.

Newton is referring to the roughly 20-25% of her clients with some type of sensitivity to nightshades.

These are plants in the Solanaceae family, which encompasses some 2,700 species of annual and perennial herbs, vines, lianas, epiphytes, shrubs and trees, including several prominent agricultural crops, medicinal plants, spices, weeds and ornamentals. Some nightshades are highly toxic while others commonly consumed by humans contain compounds that can trigger inflammation and joint pain. “It’s not a cut-and-dry problem,” says Newton. “For a lot of people, it’s not even a problem.”


Nightshades, in fact, often are the answer to growing seasonal produce for oneself. Among the easiest plants to cultivate during the summer growing season, nightshades have the advantage of built-in pest control. Alkaloids are the naturally occurring substance in nightshades that repels insects but also can harm tissues in the human body. “They are gut irritants,” says Ron Veitel, nutrition and lifestyle coach at Siskiyou Vital Medicine in Medford. “It depends on the individual; it depends on the health of their gut more than anything.”


For patients with leaky gut or rheumatoid arthritis, Veitel counsels avoidance of nightshades. To confirm a sensitivity, eliminate a food from the diet for a minimum of five days then reintroduce it, he says. The body’s allergic response may not arise for 48 hours, he adds.


Newton recommends food elimination for three to four weeks, which also allows time for inflammation to subside. A person becomes more sensitive to the food during the elimination period and often experiences a more significant reaction upon reintroduction, she says. “The most important thing you can do is actually pay attention to what your body does.”        


Eliminating nightshades, however, also means bypassing their nutritional value. Many have high levels of vitamin C, with tomatoes a leader in lycopene, an antioxidant shown to combat cancer and heart disease while promoting eye health. The capsaicin in chilies has anti-inflammatory properties, say Veitel and Newton. Another nightshade family member, goji berries have been heralded as a superfood that boosts the immune system. “Most of your nightshades are also high in antioxidants,” says Veitel. “To be fair to the nightshade family, they’re not all bad.”


Nightshades’ toxic reputation kept even innocuous species off menus in the Western world for centuries. Native to the Americas, potatoes and tomatoes imported to Europe eventually became vital to British and Mediterranean cuisines. When tomatoes made their way back to the American colonies, says Newton, they were grown strictly as ornamentals and never consumed amid fears of poisoning. “Nightshades were at one time called ‘mad apples,’” says Veitel.


Headache, even hallucination, is an extreme side effect of potatoes left too long in storage, where they build up alkaloids, says Veitel. You can significantly reduce the toxic potential by peeling potatoes and boiling them.


Just don’t lump sweet potatoes with true potatoes in the nightshade family, says Veitel. The two are only distantly related, and sweet potatoes are not classified as nightshades.

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More to Explore

Nightshade or no?

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Vegetables classified as nightshades:

  • Tomatoes, all varieties
  • Potatoes, all varieties
  • Peppers, all varieties
  • Eggplant


Vegetables often mistaken as nightshades that aren’t:

  • sweet potato
  • onion
  • zucchini
  • mushrooms





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