Are Nightshade Vegetables Bad for Me?

Nightshades are a group of flowering plants that belong to the Solanaceae family.

Researchers have studied these plants for their antioxidant and anti-inflammatory properties, which may benefit heart health and prevent certain health conditions.

The following article covers the uses of nightshades, their nutritional value, and safety considerations, including whether you should avoid them for any reason.

 

What Are Nightshade Vegetables?

There are over 2,000 types of nightshades, many of which are poisonous. However, several nightshades are considered to be safe and edible.

Common, edible nightshades include tomatoes, eggplants, potatoes, bell peppers, chili peppers, and tomatillos. Nonedible nightshades include belladonna, mandrake, and jimsonweed.

Although they are mostly considered vegetables, many nightshades are technically fruits. Botanically, tomatoes are fruits, but they are mainly classified as vegetables because of how they’re used in different dishes.

Nightshades are unique because they produce alkaloids, chemicals that protect the plant from insects, animals, and diseases. Alkaloids may be toxic to humans, especially if consumed in large amounts.

However, some alkaloids may be beneficial and have even been used for various medications.

 

Nightshade Vegetable Nutrition

Many misconceptions surround nightshades, mostly due to the presence of alkaloids. Yet, edible nightshades remain some of the most nutrient-dense whole foods available.

• • Tomatoes contain antioxidants in the form of vitamin C, vitamin A, and lycopene, a phytonutrient. They’re also a source of calcium, magnesium, potassium, and iron.
  • Eggplant is high in potassium, vitamin K, and beta-carotene, an important antioxidant. Eating eggplant also provides vitamin C, folate, manganese, and amino acids.
  • Potatoes are another rich source of potassium, as well as other minerals like magnesium, choline, and phosphorus. Potatoes also contain vitamins, including B vitamins such as B6 (pyridoxine), B3 (niacin), and B9 (folate), plus vitamin C.
  • Bell peppers are another source of antioxidants (vitamins C, A, E, and beta-carotene) and other important nutrients. Magnesium, phosphorus, potassium, zinc, and B vitamins are all found in bell peppers.
  • Hot chili peppers contain capsaicin, a bioactive ingredient linked to various health benefits. They’re also a source of amino acids, antioxidants, and vitamins and minerals like vitamin C, potassium, iron, selenium, and B vitamins.

 

• Tomatillos are similar to tomatoes but have different uses and flavors. Although tomatillos don’t contain lycopene, they do contain other important nutrients like lutein (an antioxidant), vitamin K, magnesium, vitamin C, B vitamins, and choline.

These and other edible nightshades also contain fiber, an important nutrient with known benefits for heart health. Fiber is also essential for digestive health and the gut microbiome.

Some nightshades, like potatoes, contain more starch (a type of carbohydrate) than other nightshades and non-nightshade vegetables.

Non-starchy vegetables are thought to have a lower impact on blood sugar than starchy vegetables. However, starchy vegetables also contain fiber, which helps blunt blood sugar spikes that may otherwise occur due to carbohydrates.

 

The Research on Nightshade Vegetables

There are many claims that nightshade vegetables may cause side effects or worsen certain health conditions. And while they may not fit into everyone’s diet, little research proves nightshades have harmful effects.

Instead, research shows that nightshades may possess various beneficial properties.

Antioxidant Properties

Many nightshades contain antioxidants. Antioxidants are substances in some foods that scavenge and neutralize unstable molecules known as free radicals, which are natural by-products of metabolism.

Free radicals have the potential to be harmful, damage DNA, and cause oxidative stress (an imbalance of antioxidants and free radicals, which can damage cells).

Antioxidants found in various nightshades include:

Various lab studies have confirmed the presence and effectiveness of these antioxidants in nightshades.

In one lab study, African nightshade, an edible plant, was found to reduce oxidative stress caused by free radicals. Researchers believe these results may show that African nightshade may help prevent cancer by protecting DNA from damage. However, this hasn’t been proven to be true for humans.

It’s worth noting that not all studies support the use of nightshades for oxidative stress. One study even shows that nightshades may worsen oxidative stress in inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). However, these results are also not well supported.

Nightshades may reduce oxidative stress for some but exacerbate it in others. Overall, more research is needed in this area.

Potential Anti-Inflammatory Effects

Nightshades contain fiber and phytonutrients that are thought to reduce inflammation.

One lab study found that an eggplant extract reduced the production of pro-inflammatory messenger proteins (also known as cytokines). These effects were believed to be caused by phenols and other bioactive substances in the eggplant extract.

However, there is concern that nightshades may actually be pro-inflammatory.

Older research pointed to certain substances in nightshades, like solanine and other alkaloids, as pro-inflammatory.

However, according to the Arthritis Foundation, there isn’t enough solid evidence to show that any substances in nightshades cause inflammation. The foundation recommends that people with arthritis (inflammation of the joints) only avoid nightshades if they worsen symptoms.

More research is needed to understand the relationship between nightshades and inflammation better.

Heart Health

Various nightshades may improve your heart health.

Capsaicin, a bioactive ingredient in chili peppers, has been linked to a lower risk of coronary heart disease. In one study, adults with dyslipidemia who took 4 milligrams (mg) of capsaicin daily for three months experienced increased levels of high-density lipoprotein (HDL) cholesterol (considered “good cholesterol”) and decreased levels of triglycerides (a type of fat in the blood).

Tomatoes have also been shown to be good for your heart. According to one review, the main bioactive ingredient in tomatoes, lycopene, may help lower blood pressure as well as the risk of a heart attack.

Other research shows that eggplant may help protect against metabolic syndrome, a risk factor for heart disease. A review found that eggplant may help control diabetes, reduce blood pressure, and protect against hyperlipidemia. These effects are thought to be due to the presence of antioxidants polyphenols and anthocyanins(two types of antioxidants) in eggplant.

Digestive Health

Nightshades are believed to be good for digestive health, although some reports say otherwise.

Solanine is a type of alkaloid (plant chemical) found in nightshades that may cause upset stomach and other digestive symptoms in some people. Solanine is present in green potatoes and sprouts.

Digestive side effects associated with eating too much solanine are mostly gastrointestinal and include stomach pain, diarrhea, nausea, and vomiting.

Unspoiled nightshades are considered safe to eat when consumed in normal amounts. Additionally, nightshades’ fiber and other nutrients may improve your digestive health.

Research shows that plant-based foods, including nightshades, may improve your overall gut health, including your gut microbiome, which is the natural community of microorganisms present in your gut.

According to one review, a plant-based diet increases natural prebiotics, reduces pro-inflammatory cytokines, and improves your gut’s balance of “good” (helpful) vs. “bad” (harmful) bacteria.

Despite this, some people report digestive side effects from eating certain nightshades. If you notice any issues with your digestive health after eating nightshades, it may be best to avoid them in the future.

Chronic Disease Prevention

Due to their antioxidant and anti-inflammatory properties, nightshades are thought to be therapeutic and may help prevent various chronic diseases.

In folk medicine, eggplants are used to prevent chronic inflammatory conditions like stomatitis, arthritis, and gastritis.

Inflammation and oxidative stress may lead to a myriad of conditions, like heart disease, diabetes, neurodegenerative diseases (those that damage parts of the nervous system over time), and cancer. Antioxidants and anti-inflammatory substances (like those found in nightshades) are thought to help prevent oxidative stress and, thus, chronic diseases.

At this time, however, there isn’t much research on the direct effects of nightshades on chronic diseases. While nightshades contain various nutrients and substances that may help prevent chronic diseases, more research is needed to confirm their effects.

 

How to Use Nightshade Vegetables

With so many different nightshades, many ways exist to incorporate them into a well-balanced diet.

Potatoes may be one of the most versatile foods on the planet. They can be roasted, boiled, baked, or fried and served as a main or side dish.

Eggplants are also versatile as they take on the flavor of the other foods and spices they’re cooked with. Like potatoes, eggplants can be roasted, baked, or cooked in an air fryer. They also make a great addition to grilled vegetable skewers.

Tomatoes are delicious, both raw and cooked. Many people use fresh tomatoes to make homemade salsa, ketchup, sauces, or even jams. Tomatoes are also often added to Italian and Mexican dishes and can be grilled, fried, or roasted.

Tomatillos may also be eaten raw or cooked and are often used in soups, salads, salsa, or guacamole. Tomatillos can also be roasted, broiled, or fried and served as a side dish or added as a garnish.

Bell peppers and chili peppers are commonly used to add flavor and spice to recipes. Stuffed bell peppers are a crowd favorite, but there are many other ways to enjoy peppers. Peppers are great in fajitas, curries, salads, pasta, veggie skewers, chili, or stir fry.

Cooking nightshades may make them more easily digestible for some people. However, cooking nightshades using specific methods or for too long may lose some nutritional value.

According to one study, potatoes (and some other vegetables) may be more likely to lose certain nutrients if boiled. However, this will depend on the vegetable and the nutrients inside.

To prevent excess nutrient loss, it’s recommended that you don’t cook nightshades or other vegetables for extended periods.

While some nutrients may decrease slightly when vegetables are cooked, others may actually increase. Lycopene, calcium, magnesium, and carotenoids may increase and become more easily absorbed when cooking nightshades.

Many nutrients, including fiber, are present in vegetable skins. Potatoes, tomatoes, eggplant, peppers, and other nightshades have edible skins that don’t need to be peeled away.

 

Are Nightshade Vegetables Bad for Me?

Some people believe that nightshades are bad for them. However, most people can enjoy nightshades as a part of a healthy, well-balanced diet.

Of course, you should avoid any nightshades if you are allergic to them. Seek immediate medical attention if you have any signs of a severe allergic reaction such as itching, hives, or shortness of breath.

Some people may experience an upset stomach when eating certain nightshades.

For example, small studies performed on people with Crohn’s disease (a type of IBD) have found that eliminating nightshades may help with symptom management. However, more large-scale data are needed to back these findings up.

There are also anecdotal claims that nightshades may trigger or worsen autoimmune disorders, such as rheumatoid arthritis (RA), a disease marked by inflammation. However, research shows that nightshades may reduce inflammation rather than cause it. Nightshades may also improve gut permeability, a common issue in those with RA.

If you have an autoimmune condition or a possible sensitivity, it may not be necessary to eliminate all nightshades from your diet.

You may choose to try an elimination diet to determine if any particular nightshade is causing side effects or worsening your symptoms. An elimination diet should be done under the guidance of a healthcare provider, such as a registered dietitian.

 

Summary

Nightshades are fruits and vegetables that belong to the Solanaceae family of plants. Popular edible nightshades include potatoes, tomatoes, peppers, and eggplant.

Nightshades are rich in vitamins, minerals, fiber, and phytochemicals, including antioxidants.

Many people are confused over the benefits and drawbacks of nightshades. While some reports show that nightshades and beneficial to eat, others show that they may cause side effects.

In general, there is no strong evidence that nightshades aren’t safe to eat. Some people may have sensitivities to nightshades, however, and may need to avoid eating them.

Talk with a healthcare provider to learn more about the science behind nightshades.