Nightshade Vegetables and Inflammation: Can They Help with Arthritis Symptoms?

Medically reviewed by Natalie Butler, RD, LD on March 28, 2017Written by Annette McDermott

Not all nightshade plants are safe to eat

Nightshade vegetables are members of the Solanaceae family of flowering plants. Most nightshade plants aren’t edible such as tobacco and the deadly herb, belladonna.

A handful of nightshade vegetables, however, are edible and well-known staples in our diets, including:

  • tomatoes
  • eggplant
  • potatoes
  • peppers

All nightshade plants contain compounds called alkaloids. One alkaloid found in nightshade vegetables, solanine, may be toxic in large quantities or in a green potato. There’s no evidence solanine is harmful in typical food amounts. And solanine isn’t only found in nightshades—blueberries, huckleberries, and artichokes contain it, too.

Thanks to anecdotal evidence, nightshade vegetables have earned a bad reputation for causing inflammation in the body. But not everyone with painful joints who eliminates nightshades from their diet experiences pain relief and some evidence suggests that the nutrition content of nightshades may help with arthritis symptoms.

Keep reading to learn how these vegetables may affect inflammation within the body, their potential health benefits, and more.

What the research says about nightshade vegetables and arthritis

According to the Arthritis Foundation, the belief that eating nightshade vegetables worsens arthritis is a myth. They claim people with arthritis may benefit from the high nutrition content in nightshades.

For example, researchers in one 2011 study found that inflammation and DNA damage was reduced in healthy men who ate yellow or purple potatoes, which are nightshade vegetables, for six weeks.

However, more research is needed. To date, there’s little scientific research to draw a conclusion either way.

Health benefits of popular nightshades

Most nightshade vegetables contain an abundance of nutrients. They’re also readily-available and easy-to-prepare. In some cases, the benefits of eating nightshade vegetables may outweigh any inflammation risk.

1. Peppers

peppers

Peppers, including bell peppers and chili peppers, are low in fat and calories.

They’re a good source of nutrients such as:

  • vitamin C
  • fiber
  • vitamin K
  • B vitamins

The capsaicin in chili peppers may relieve arthritis pain by reducing a specific pain transmitter in your nerves called Substance P. Capsaicin, which is a common ingredient in many pain-relieving creams. It may cause mild burning or a skin reaction when applied topically.

2. Potatoes

potatoes

The white potato often gets a bad rap because it’s a starchy carb, but all varieties of potatoes are nutritionally-dense. They can be a part of a healthy diet when eaten in moderation and not fried or slathered in butter and sour cream.

Potatoes are fat-free and a good source of fiber. Fiber helps to keep you fuller longer so you may eat less. Since they contain sodium and potassium, potatoes also help keep your electrolytes in balance.

They’re also a good source of:

  • vitamin C
  • vitamin B6
  • niacin
  • manganese
  • iron
  • copper
  • folate

The healthiest potato is a baked potato. Add herbs and a dollop of Greek yogurt instead of butter and sour cream. Don’t be shy about trying different varieties, especially since pigmented potatoes may give you an anti-inflammatory bang for your buck.

3. Tomatoes

tomatoes

Technically, tomatoes aren’t a vegetable; they’re a fruit. They contain all four of the carotenoid antioxidants, which include:

  • lycopene
  • beta-carotene
  • alpha-carotene
  • lutein

Lycopene is the most powerful carotenoid. It’s thought to help prevent some types of cancer, help prevent heart disease, and boost immunity. Some research has shown tomatoes have anti-inflammatory abilities, although more research is needed.

Tomatoes are a good source of:

  • vitamin E
  • vitamin A
  • potassium
  • calcium
  • vitamin K
  • vitamin B

Add fresh, diced tomatoes to a green salad or make fresh tomato juice. Tomatoes are delicious in vegetable soup and chili, too.

4. Eggplant

eggplant

Like tomatoes, eggplant is also a fruit. It has no fat or cholesterol. Eggplant isn’t high in any one vitamin or mineral, but it contains small amounts of most essential vitamins and minerals.

According to one 2015 study, eggplant stalk extract may help reduce inflammation. More research is needed to determine if eggplant fruit has the same abilities.

To enjoy eggplant in your diet, go beyond a fat- and calorie-laden eggplant Parmesan casserole. Instead, try sprinkling sliced eggplant with olive oil and herbs, then roasting or grilling. You can also steam eggplant, or add sautéed slices to your favorite veggie pizza.

Learn more: The 8 most nutritious nightshade plants »

Should you remove nightshades from your diet?

There’s no scientific evidence to date that shows nightshade vegetables cause inflammation. Even so, that doesn’t mean anecdotal evidence is wrong. Food allergies and intolerances are on the rise worldwide.

To know for certain how nightshades impact you, try an elimination diet. Stop eating all nightshades for two weeks to see if your symptoms improve. If you’re not sure, add them back into your diet to see if your symptoms get worse.

Discontinue eating and see the emergency room and your doctor if you experience symptoms such as these after eating any food, which may suggest you’re having a life-threatening anaphylactic reaction:

  • mouth-tingling
  • rash or hives
  • itching
  • swelling of the face, tongue, or throat
  • difficulty breathing or wheezing
  • gastrointestinal distress
  • dizziness or lightheadedness
  • fainting

If you experience one or more of these symptoms, you may be experiencing an allergic reaction to nightshade. Food intolerances are different from food allergy symptoms in that they don’t pose an anaphylactic risk, but can still produce uncomfortable symptoms like pain, discomfort, aches, and gastrointestinal issues. A dietitian can help you follow an elimination diet to identify and manage any allergies and intolerances.

Anti-inflammatory foods to try

Many foods are thought to help reduce inflammation in the body. Eating them regularly may help reduce joint pain and swelling. Some popular anti-inflammatory foods include:

1. Omega-3 fatty acids

omega 3

Foods high in omega-3 fatty acids may help fight inflammation by limiting two proteins that cause inflammation. Omega-3s may also help reduce your risk of heart disease and help lower cholesterol.

Common options include:

  • salmon
  • sardines
  • mackerel
  • flaxseed oil
  • chia seeds
  • walnuts
  • soybeans
  • spinach

2. Produce

produce

Berries, leafy greens, and other fresh produce are chock full of antioxidants. A diet rich in antioxidants helps boost your immunity and may reduce the risk of inflammation. Eating a variety of fruits and vegetables is one of the best things you can do for your overall health.

It may help:

  • prevent weight gain
  • reduce your risk of heart attack and stroke
  • lower blood pressure
  • reduce your risk of some cancers
  • reduce your risk of bone loss

3. High-fiber foods

fiber

According to the Arthritis Foundation, foods high in fiber such as nuts, whole grains, and produce may help battle inflammation markers common in arthritis in a few ways:

  • It helps lower C-reactive protein levels in the blood. C-reactive protein has been linked to inflammatory diseases such as rheumatoid arthritis.
  • Fiber may also prevent weight gain, another factor linked to inflammation.
  • Finally, fiber is the meal of choice for healthy bacteria in your gut. Research has shown a healthy microbiome may help reduce inflammation.

4. Olive oil

oil

Olive oil is a staple in the anti-inflammatory Mediterranean diet. According to a 2011 study, olive oil contains several compounds with anti-inflammatory abilities. One compound, a phenolic compound known as oleocanthal, was shown to have as potent anti-inflammatory abilities as ibuprofen.

5. Onions

onion

Onions contain a bioflavonoid called quercetin. According to one 2006 study, quercetin has anti-inflammatory and antioxidant abilities. It may help prevent allergic reaction by stopping the release of histamine and mast cell secretion.

Other foods that contain quercetin are:

  • apples
  • leafy green vegetables
  • beans
  • grapefruit

Limit or avoid foods proven to be inflammatory

Not only is it important to add foods that prevent inflammation to your diet, but you should also avoid inflammatory foods.

Foods high in saturated fat and trans fats are linked to inflammation in the body. Some of these items are:

  • fried foods
  • potato chips, crackers, and other processed snack foods
  • processed baked goods such as cakes and cookies
  • foods cooked at high temperatures
  • foods high in sugar
  • beverages high in sugar such as soda and sweetened fruit juice
  • foods high in sodium

Dairy products may cause inflammation in some people. Research shows a link between inflammation and people allergic to cow’s milk. Dairy may also worsen inflammation in people with metabolic disorders. To see how dairy impacts your arthritis symptoms, eliminate it from your diet for two weeks.

Learn more: Foods to avoid with arthritis »

The bottom line

It’s okay to add nightshade vegetables to your anti-inflammatory diet. Unless you eat huge quantities or green potatoes, they don’t contain enough solanine to make you sick. And evidence to date does not support a link between nightshades and inflammation. If you’re concerned, however, talk to your doctor or a dietitian. They’re the best resource to determine the diet that’s right for you.

Keep reading: Anti-inflammatory diet for rheumatoid arthritis »

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