Nightshade vegetables are a family of plants that includes tomatoes, potatoes, peppers, and eggplant. They are a good source of vitamins, minerals, and antioxidants, but some people believe that they can be inflammatory for people with autoimmune diseases. Today I’m discussing this group of vegetables and why we might need to be careful about eating them.
How do Nightshades Trigger Inflammation?
Nightshade vegetables contain compounds called glycoalkaloids. Glycoalkaloids are natural pesticides that plants produce to protect themselves from pests. Some research suggests that glycoalkaloids can be inflammatory for people with autoimmune diseases. For example, both a 2002 study and a 2010 study found that glycoalkaloids from potatoes can damage the gut lining and trigger inflammation in mice with IBD. Glycoalkaloids have also been shown to trigger intestinal permeability.
Nightshade vegetables also contain lectins. Lectins are proteins that bind to carbohydrates in the gut. Research has found that lectins can be inflammatory and can trigger autoimmune responses in some people. One study found that lectins can activate the NLRP3 Inflammasome. This is a protein complex that regulates the innate immune system and inflammatory signaling. This study concluded that dietary lectins may promote inflammatory diseases Lectins are also known to trigger intestinal permeability or leaky gut. Intestinal permeability is an issue because it allows foreign objects to sneak through your intestinal lining. Your body may then mount an attack on those foreign objects, which can trigger inflammation.
Capsaicin is the spicy compound that’s found in peppers, a nightshade vegetable. Research is mixed on the benefits or downsides of capsaicin. In one study, researchers found that mice exposed to capsaicin saw an increase in leukocytes and a shift toward a more inflammatory microbiome. However, another study found that low doses of capsaicin may actually lower the risk of GI-related cancer. Capsaicin can also irritate mucus membranes, including those in the gut.
Should people with autoimmune diseases avoid nightshade vegetables?
Choose organic nightshade vegetables whenever possible. Organic vegetables have lower levels of glycoalkaloids than non-organic vegetables.
Peel and cook nightshade vegetables before eating them. Peeling and cooking can help to reduce the levels of glycoalkaloids and lectins in nightshade vegetables. Pressure cooking can break down lectins very efficiently too.
Avoid eating green potatoes and unripe tomatoes. Green potatoes and unripe tomatoes have higher levels of glycoalkaloids than ripe potatoes and tomatoes.
Combine nightshade vegetables with other anti-inflammatory foods, such as leafy greens, berries, and fatty fish. Anti-inflammatory foods can help to offset the potential inflammatory effects of nightshade vegetables.