Nightshade Allergy 101: Everything You Need to Know

Originally published on September 9, 2020; Updated and republished on October 18, 2022.

Do you have a nightshade allergy? Do you suspect that your current symptoms are caused by a food allergy and you’re scared you’ll never eat a normal meal again? This guide will help you understand what nightshades are and how it can affect your body.

What are Nightshades?

Nightshade plants come from a large family of flowering plants known as Solanaceae (source). It’s somber sounding name comes from its toxic and poisonous properties (source).

Alkaloids are chemical compounds that can cause Solanaceae plants to be highly toxic or deadly, like belladonna and jimsonweed (source)(source). The alkaloids are a natural defense mechanism against predators and pests (source). Many nightshade plants are inedible.

An example of an edible nightshade is the white potato. White potatoes are well tolerated by many despite containing alkaloids. If your potato has turned green, you shouldn’t eat it because of its increased levels of an alkaloid called solanine(source). In high amounts, solanine can cause digestive issues (source).

See the list below to learn what other foods are considered nightshades.

Nightshade Food List

• Chili peppers (source)
• Bell peppers/Pimenton (source) 
• Spices made from peppers (chili powder, paprika, red pepper, curry powder,  cayenne pepper) 
• Tomatoes (including tomatillos) (source)
• Eggplants (source)
• White Potatoes (source)
• Goji berries (source)
• Ashwagandha (source)
• Cape gooseberries (source)
• Huckleberries (source)

Wait, wait– but aren’t these healthy foods?  Nightshades are plant-based foods that provide nutrients you don’t want to miss out on.  For example, tomatoes have several carotenoids like lycopene for heart health and lutein for eye health. Just a half cup of red bell peppers your daily Vitamin C needs (source). Ashwagandha is a medicinal herb that may help reduce stress (source). 

Though most people can eat these foods without problems, a small percentage of the population will react adversely to eating nightshade vegetables.

What’s the Problem with Nightshades?

Nightshades and Joint Pain

Some people claim nightshades trigger arthritic joint pain, though there hasn’t been any scientific evidence to back this up (source). Despite the lack of research, some have found symptom relief with the removal of nightshade foods (source). If this describes you and you want to stop eating nightshades, it’s best to find alternatives to maintain proper nutrition.

Nightshades and Leaky Gut

Lectins are proteins found in nightshades that aremsaid to be antinutritive(source). Lectins go undigested in the gut and cause cell damage in the gastrointestinal tissue(source). Adversely influencing the immune health of the gut and reducing nutrient digestion and absorption are other ways lectin causes issues (source). The contribution of lectins on increasing gut permeability may contribute to leaky gut (source).

Nightshades and Autoimmune Disease

Autoimmune diseases are the result of an immune response where the body attacks its organs (source). Celiac disease and inflammatory bowel disease (IBD) are two well known autoimmune diseases. 

The alkaloids and lectin found in nightshades may stimulate an immune response, exacerbating autoimmune diseases (source).

In two studies on mice, the consumption of potato alkaloids caused an increased inflammatory response (source)(source).

Potential Allergy

The last reason some people avoid nightshades is if they have allergic symptoms after eating them. This could be a sign of a food allergy or sensitivity to nightshade vegetables.

What is a Nightshade Allergy?

Food allergies occur when there’s an adverse reaction to food. This causes an immune response or a non-immune response in your body (source).

An adverse reaction to an alkaloid causes a nightshade allergy. Solanine, tropane, nicotine, and capsaicin are a few alkaloids in nightshade vegetables (source).

Nightshade Allergy Symptoms

According to Medical News Today, the symptoms of a nightshade allergy are:

• Vomiting
• Nausea
• Hives and skin rashes
• Inflammation
• Excess mucus production
• Achy joints and muscles
• Itchiness

How Do I Know if I Have a Nightshade Allergy?

A simple non-invasive approach to discovering a food allergy or intolerance is doing an elimination diet. This is where you avoid the foods you believe are causing issues. You can keep a food journal of what you’re eating and any symptoms you may experience. 

After a few weeks, you can add the potential culprit foods to your diet and see if your symptoms return. 

If you think you may have a nightshade allergy, you can get help from a Certified Leap Specialist or Dietitian.

What is a Nightshade Intolerance?

Food intolerances or sensitivities occur when an individual component of a food cannot be broken down by the digestive system’s enzymes. Digestive issues are a result of a nightshade intolerance. These are usually not as serious as food allergies.

According to Medical News Today, the symptoms of a nightshade intolerance are:

• Gas and bloating
• Diarrhea
• Nausea
• Heartburn

If you think you may have a nightshade intolerance or sensitivity, you can work with a Certified Leap Specialist or Dietitian about removing nightshade foods from your diet.

Hidden Nightshade Ingredients

Reading labels is a top priority when you’re managing a food allergy or sensitivity. Always check your nutrition label to avoid ingredients that could be causing you harm. Below, you’ll find a short list of where nightshades hide.

Food Additives

• Some foods (deli meats, sauces) are made with paprika for added color (source).
• Potato starch is a common food additive (source)

Medications

• Some medications contain belladonna (source).
• Some medications for inflammation and pain contain capsaicin (source).

Alcohol

• Vodka is produced using potatoes (source).

Nightshade Substitutions when Cooking

• Swap white potato for sweet potato, parsnip, boiled green banana, butternut squash, or plantain.
• Swap paprika for black pepper, garlic, cumin, or turmeric.
• Swap eggplant for mushroom, zucchini, or artichokes.
• Swap goji berries for cranberries. 
• Swap peppers for celery, carrot, radish, or sweet onion.
• Swap tomato sauce for pesto, olive oil, or aioli.

Is Coffee a Nightshade?

If you are not sure if a particular food is a nightshade, search its scientific name. If it is not in the Solanaceae family, it is not a nightshade.

The coffee bean comes from the Coffea plant (source). This plant is not a member of the Solanaceae family, so it is not a nightshade.

Is Cucumber a Nightshade?

Cucumber is a member of the Cucurbitaceae gourd family (source), which does not relate to the Solanaceae family. Cucumber is not a nightshade.

Is Sweet Potato a Nightshade?

No. Sweet Potatoes are not in the Nightshade food family.

However, some people can’t tolerate sweet potatoes for other reasons.

Bottom Line

You should only consider avoiding nightshades if they cause you to feel bad. Nightshade vegetables are nutritious foods with health benefits, so if you do not have an autoimmune disease or experience issues after eating them, do not avoid them!

If you do discover you have a nightshade allergy, you are not alone! You are on your way to feeling more like yourself again. There are plenty of others just like you who are following nightshade-free diets and have plenty of tips and recipes online. 

Be sure to plan a meal with vegetable alternatives to ensure you’re still reaping all of the nutrition benefits of your new diet.

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