The Truth About Nightshades: Are They Bad for Your Arthritis?
- Cristina Montoya, RD
- Aug 23
- 4 min read
Updated: Sep 30
I’ve lived with Rheumatoid Arthritis and Sjögren’s Disease for two decades. Both are unpredictable chronic illnesses with no known cure.
One piece of advice I’ve heard repeatedly is, “Cut out the nightshades; they're bad for your arthritis.” Tomatoes, eggplants, peppers, and potatoes are everyday staples often portrayed as villains in the autoimmune world.
But is this dietary advice backed by evidence, or is it just another diet myth that refuses to die?
In this post, I’m diving deep into the truth behind the nightshade debate.
Whether you’re navigating a new diagnosis of inflammatory arthritis or simply curious about the connection between food and inflammation, let’s explore what the research really says—and what my own experience has taught me.
In this article:
What are nightshades?
Do nightshade vegetables cause inflammation?
Nightshades and gut health
5 Common nightshades with anti-inflammatory benefits
In summary, are nightshades really bad for you?
What are Nightshades?
Nightshade plants belong to the Solanaceae family. They got their name because these plants prefer to grow in the shade. Common nightshade plants include:
Hot peppers
Cayenne pepper, paprika (Capsaicin)
Eggplants
Peppers
Potatoes
Tomatoes
Goji berries
Blueberries (while not a nightshade, they contain solanine)
Do Nightshade Vegetables Cause Inflammation?
Nightshade vegetables naturally produce alkaloids as a defense mechanism against external threats.
Solanine is a type of alkaloid found in nightshade vegetables, particularly potatoes. It can be toxic if consumed in large amounts, but don’t worry. Solanine is mostly found in the green parts of a plant, such as the leaves and stems.
Early animal studies showed that large doses of alkaloids and lectins might harm the gut lining in mice. This can compromise the intestinal barrier, leading to a "leaky gut" and causing inflammation. However, these amounts were higher than what a human would typically consume in a day.
On TikTok, someone shamed me, claiming my joint deformities were due to not cutting out nightshades immediately after my diagnosis. Even as a Dietitian, I'm not immune to unsolicited advice.
Nightshades and Gut Health
A new hypothesis is emerging regarding the effects of nightshades on gut health, particularly in individuals with Inflammatory Bowel Disease and Irritable Bowel Syndrome.
A recent review suggested that glycoalkaloids may damage the gut lining and activate mast cells, which are components of the immune system. When mast cells are triggered, they can cause inflammation and allergic-like reactions in the gut.
However, research is still limited. Currently, there are no tests or clinical evaluations that can accurately determine sensitivity.
5 Common Nightshades with Anti-Inflammatory Benefits
The short answer is no; nightshades can be part of an anti-inflammatory diet.
By removing nightshades from your diet, you miss out on crucial antioxidants with anti-inflammatory properties. These include phytochemicals and fibers, which are vital for maintaining the integrity of the gut barrier.
1. Eggplants
✔️ Low calorie
✔️ Low glycemic index (promotes blood sugar control)
✔️ Good source of fiber (2.5g in a cup)
✔️ Low FODMAP (1 cup)
✔️ High in antioxidants, especially anthocyanins
✔️ Easy to add to your diet (grilled, baked, roasted)
🍆 In case you are in the mood for some Italian-inspired food, try Parmesan Polenta and Eggplant.
2. Cayenne and Paprika
Capsaicin is an alkaloid found in cayenne and paprika, common spices in the Solanaceae family. It is a chili pepper extract that helps relieve pain.
A study found that dietary capsaicin reduced the inflammatory responses in people with obesity. This suggests it may be useful in managing inflammation in inflammatory and autoimmune arthritis.
3. Bell Peppers
Peppers are a good source of vitamin C and lycopene, which are antioxidants providing anti-inflammatory effects.
Their vibrant colors and crisp textures make them visually and nutritionally appealing. This makes it easier to achieve the goal of "eating a rainbow" every day.
🥗 Looking for a refreshing side? Try this Summer Ginger Coleslaw by Arthritis Society Canada.
4. Potatoes
Potatoes are readily available in Canada and contain high amounts of vitamin C and potassium.
Potassium has been shown to have anti-inflammatory properties that could reduce pain caused by arthritis.
Potatoes are also a good source of vitamin B6, folate, and fiber. When cooked, cooled, and reheated, the amount of resistant starch increases. This is beneficial for the gut microbiome and helps reduce inflammation.
The main concern is about consuming "green" potatoes. Greening occurs when a potato is exposed to light while growing, leading to increased solanine levels and a bitter taste. This is something to be cautious of, particularly if you are at risk for mast cell activation syndrome!
🥗 Enjoy a Savoury Chickpea Salad for gut health support!
5. Tomatoes
Tomatoes are high in the antioxidant lycopene and vitamins A and C, which may reduce inflammation.
An animal study indicated that a concentrated lycopene emulsion could have anti-inflammatory effects in rheumatoid arthritis.
Lycopene absorption from food improves when tomatoes or bell peppers are cooked.
Sofrito, a tomato-based sauce with olive oil, onions, and garlic, is a great way to enjoy lycopene benefits. It can be used as a side sauce, mixed with rice and beans, or as a topping for tacos, fish, or chicken.
🍅 Cayenne Haddock with Sofrito is a perfect way to kick-start your anti-inflammatory lifestyle.
In Summary, Are Nightshades Really Bad for You?
Research on the effects of solanine and inflammation in arthritis is limited and mixed. Two separate studies on mice aimed to explore this relationship. One study found that solanine causes inflammation, while the other showed it decreases inflammation.
Pay attention to your body. If you notice a flare-up within 24 hours of eating nightshades, consider cutting them out or reducing their intake for two weeks.
Don't eliminate them for life; reintroduce one vegetable or spice every few days.
Maintain a journal to note any new symptoms. Additionally, consider other external stressors in your life, such as weather changes, physical and mental stress, inadequate sleep, or increased disease activity.
This article was originally written on August 23, 2021, and revised on August 23, 2025.
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