What Are Nightshade Foods & How to Identify an Intolerance

Delicious food giveth and delicious food taketh away, and anyone who has had to deal with any sort of food intolerance or digestive issues knows the latter as a far too familiar fact. Although the word “nightshade” is typically associated with the deadly, deep-purple Atropa belladonna plant, there is actually an entire family of nightshade vegetables. While they won’t kill you, nightshade plants can give a few unlucky folks a myriad of unpleasant or painful symptoms.

Nightshades belong to the Solanaceae family, which is home to roughly 2,000 varieties of plants. These plants’ distinguishing feature is their high alkaloid content, chemical compounds used by the plants to protect themselves from insects that might try to eat them. Some of these alkaloids are old friends — capsaicin, for example, is an alkaloid found in peppers responsible for offering that irresistible, tongue-burning heat to your favorite chilis and serranos. Nicotine, tropane, and solanine are other common alkaloids, none of which are exactly good for humans. Not deadly, but not great.

If you’re finding yourself bloated, uncomfortable, constipated, gassy, or otherwise symptomatic after eating certain foods found within the nightshade family, it might be worth finding out if you are nightshade intolerant or allergic.

The rub of it all? Nightshade vegetables are everywhere. Found in just about every cuisine worldwide and used as the basis for a wide variety of common dishes, the following foods are considered part of the Solanaceae, or nightshade, fam:

• Tomatoes and tomato products (this includes marinara, salsa, and ketchup)
• Tomatillos (you too, salsa verde)
• White and red potatoes
• Eggplant
• All sweet and spicy peppers
• Pimentos
• Goji berries
• Ground cherries
• Ashwagandha
• Red spices: curry, chili, and cayenne powder; red pepper flakes; paprika

If you’ve noticed feeling one or more of the following symptoms after eating one or more of these nightshade foods, it could be worth looking into whether you have a nightshade intolerance or allergy. Symptoms of a nightshade intolerance include:

• Bloating and gas
• Heartburn
• Nausea
• Diarrhea
• Itchy eyes
• Excessive mucus
• Changes in mood
• Constipation

Compared to an allergy, an intolerance is not nearly as serious. A food intolerance suggests a deficiency of enzymes that help break down a particular food, while an allergy presents the serious possibility of anaphylactic shock, immunodeficiencies, chronic bad skin, and more. Symptoms of a nightshade allergy include:

• Hives or skin rash
• Nasal congestion
• Wheezing or coughing
• Pale skin

Call 911 or seek emergency treatment if you experience:

• Difficulty breathing
• A swollen throat (feeling like you have a “lump” in your throat)
• Dizziness, lightheadedness, or loss of consciousness

If you have eaten one or more foods from the nightshade family and experienced any of the symptoms listed for a nightshade allergy, we recommend seeking out a medical professional’s opinion. If you’ve only experienced symptoms of a nightshade intolerance, this can be assessed, corrected, and treated safely from home. The best way to identify an intolerance is through an elimination diet and food challenge tests.

Because our normal diet consists of meals with endless combinations of different ingredients, some nightshade and some not, it’s difficult to identify food sensitivities without first eliminating the questionable foods entirely. An elimination diet just does that: for two to four weeks, certain foods are entirely removed from the diet. Once those foods have been entirely processed and removed by the body, they can be slowly reintroduced through a “food challenge test.” Like with any other restrictive diet, it’s best to approach an elimination diet in the right attitude. Luckily, the University of Wisconsin breaks down the basics of an elimination diet in layman’s terms.

Step One: Plan, plan, plan!

An elimination diet isn’t something to dive headfirst into; begin your diet prep by keeping a food and symptoms journal for at least one full week. For a minimum of seven days, write down everything you’ve eaten (particularly any nightshade-related ingredients) and any corresponding symptoms you’ve had. Since symptoms might not show up until hours after a troublesome meal, be sure to monitor your symptoms before, during, and after your meals. Asking yourself these questions is a good place to start with your food/symptoms journaling:

• What foods do you eat the most?
• What foods do you crave the most?
• What foods do you eat to feel better emotionally?
• What foods do you have trouble giving up?

More often than not, these foods will be the ones you’ll want to monitor the most closely during your preparation period.

During this time, you should also do a bit of self-reflection and assessment to determine whether you have enough time, mental and physical energy, or resources to successfully and safely go through with this new dietary regimen. Consider your external environment. Have you recently picked up extra work, causing any and all downtime to be a stressed-out “break” before your next shift? Is your schedule jam-packed from 6 a.m. to 10 p.m.? Are you experiencing any financial strain that is causing your diet to shift to cheaper, more readily available options?

If any of these questions can be answered in the affirmative by you, it might be best to wait to start your elimination diet until you have the mental clarity, time, and resources to fully immerse yourself in the process.

Step Two: Avoid!

Next, the “easy” part. Completely eliminating certain ingredients from your diet means just that: completely. If you accidentally slip up and eat an ingredient or food containing the ingredient of something you planned on testing during your food challenge phase, you’ll have to completely start the elimination process over in order to get the most accurate assessment. This process should take roughly two to four weeks. Make sure to pay close attention to nutritional labels, as these nightshade ingredients might be hiding in your prepackaged goodies without you realizing it. You should also be wary of eating out at restaurants, which makes it more difficult to ensure the nutritional and preparation information of the dish you’re served.

Step Three: Challenge.

After you’ve gone 2-4 weeks without any nightshade foods in your diet, you can now begin the “food challenge” phase. This involves slowly reintroducing foods-in-question and closely monitoring your physical and mental symptoms. Because your body might be reintroduced to a food to which its sensitive or allergic, be sure to test your foods slowly. Overloading your body with symptom-inducing foods can mess with your final results.

It’s best to be symptom-free for at least five days before beginning your food challenges. When you do reintroduce your foods, it’s best to consume them in the purest form possible: in the case of nightshade veggies, opt for raw or cook with no extra spices, breading, oil, etc. Begin by eating a very small serving of one nightshade veggie. Wait a few hours, monitor your symptoms, and repeat the process for the next three days, slowly increasing the serving size each time. If you feel no symptoms at the end of four days, chances are, you’re in the clear. If you feel any symptoms, put a mark beside the cuisine culprit and move on.

If you experienced symptoms in your first food challenge, wait until you’ve been symptom-free for five days and repeat the process with a new ingredient. From there, you can continue testing all the foods you eliminated until you’ve determined which foods create symptoms and which don’t.

Step Four: Making the long term change.

You might need to try an elimination diet a few times to get the most accurate assessment. Typically, any foods that didn’t cause symptoms can be reintroduced into your normal diet with no problem. Foods that left you feeling bloated, gassy, or otherwise uncomfortable might be best left avoided. Of course, if you’re willing to deal with the digestive consequences of keeping those flavors in your life, an ignored nightshade intolerance won’t kill you.

But if you want to live your life with a bubble-free belly, consider switching out some of your nightshade favorites with non-nightshade alternatives (both in flavor and nutrition):

Tomatoes

• For texture and flavor similar to raw tomatoes: underripe mango
• Lightly sauteed zucchini easily replaces lightly-cooked tomatoes
• Canned pumpkin, butternut squash, or sweet potato puree
• Umeboshi paste

White and red potatoes

• Sweet potatoes or yams
• Cauliflower

Eggplant

• Portabella or shitake mushrooms
• Zucchini
• Root veggies like turnips, rutabagas, and radishes
• Non-sweet winter squash

Peppers

• For the crispy bite of a bell pepper: celery, radishes, zucchini, or Swiss chard
• For the heat of a spicy pepper: black pepper, ginger, cloves, garlic, mustard powder, horseradish, or wasabi (These are also great replacements for red powder spices!)