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Recent years have witnessed a massive debate on whether nightshade vegetables are good or bad for health. There are critics and supporters both passionately weighing in on this debate. But, what exactly are nightshade vegetables, and are they bad for your health?  A persistent myth about arthritis involves preventing the nightshade family of vegetables, of which berries, white potatoes, eggplant, and bell peppers are all members.

Some folks blame arthritic swelling, stiffness, and pain on a buildup of solanine, a bitter-tasting compound found in nightshade plants.

It's a fact that solanine is among those glycoalkaloids which make"deadly nightshade" deadly, and green potato leaves, sprouts, and stalks poisonous. According to Cleveland Clinic, it's highly improbable that avoiding the trace quantities of solanine found in nightshade vegetables will relieve your arthritic inflammation or pain. Research to support this claim simply is not there. Moreover, it would be a shame to remove these nutritious foods out of your diet.


What are Nightshade Vegetables?

Nightshade vegetables are the parts of the flowering plants from the Solanaceae family that are edible. There are over 2,000 types of plants in the nightshade family, but there are very few of them that get consumed as food. 

Here are some of the most commonly used nightshade vegetables:

·     Potatoes: All types of potatoes except yams and sweet potatoes

·     Tomatoes: All types of tomatoes and related tomato products

·     Eggplants or aubergines

·     Peppers: Includes bell, cayenne, jalapeno, chili, sweet, and other types of peppers as well

·     Red Spices: Chili powder, cayenne powder, crushed red pepper, curry powder, paprika

See: Sun Dried Tomatoes Nutrition Facts & Health Benefits

Are Nightshades good for you?

Nightshades are good nutrition sources

Doctors often encourage people to consume nightshade vegetables because of the high nutrient density, meaning that they contain a lot of nutrients in just a small number of calories. Here's a nutrition profile of some nightshade vegetables:

·     Tomatoes: They are excellent sources of vitamins A and C, and they are also rich in the antioxidant lycopene. All these compounds lower the markers of inflammation in the body. They also reduce the risk of many chronic diseases.1,2

·     Peppers: Peppers are powerhouses of vitamin C. Vitamin C has many health benefits, one of which includes boosting the absorption of iron.3

·     Potatoes: If you have potatoes with the skins, then you get proper amounts of vitamin B6, potassium, and manganese.4

·     Eggplants: Eggplants are a great source of dietary fiber. The body requires fiber for regulating bowel movements and also lowers the risk of heart disease.5 

See: Sweet Potato & Diabetes

Do nightshade vegetables cause inflammation?

However, in spite of their high nutrient content, nightshades may also be harmful to some. One of the reasons why some people believe nightshade vegetables to be problematic is because nightshades cause their inflammation or worsen arthritis-related inflammation. 

Many people have also reported a worsening of their arthritis pain and other symptoms upon consuming nightshades that contain solanine. However, there is no evidence or research to support that the compound solanine has any effect on arthritis pain or inflammation.  

Though some people might report a worsening of symptoms when eating nightshades that contain solanine, there's absolutely no research to support that solanine has a direct effect on inflammation or arthritis pain. Instead, these symptoms could be caused by or associated with a food sensitivity to the nightshade family.

A 2010 study found that eating yellow or purple potatoes may lower inflammation and prevent DNA damage. The researchers established that these potatoes prevent cell damage due to the high levels of antioxidants in these potatoes.6

In spite of this, if an individual believes that they might have a food intolerance or food allergy into nightshades, they could eliminate them from their diet and take note of any effects this has for their symptoms. If you choose to eliminate them, it is critical to be certain that you're still getting important antioxidants and vitamins from different sources.

See: Rheumatoid arthritis Complementary treatment with Probiotics

Nightshades may worsen IBD

Inflammatory bowel syndrome (IBS) or disease (IBD) is an umbrella term used for autoimmune diseases that cause inflammation of the digestive tract.  In people who have IBD, the lining of the intestine fails to function correctly, allowing many harmful substances and bacteria to enter the bloodstream directly. This condition is known as increased intestinal permeability or leaky gut syndrome.7  When you have a leaky gut, your immune system starts attacking the harmful substances that enter the bloodstream, causing further inflammation in the stomach. 

While there is limited research, but a few animal studies have suggested that the presence of alkaloids in nightshades may further irritate the intestinal lining in people with IBD.  For example, in two different studies done on mice with IBD, it was found that the alkaloids present in potatoes adversely affected the intestinal permeability and also increased inflammation in the intestines.8,9  Two more test-tube studies have also suggested that pectin (a fiber present in tomatoes) and capsaicin (present in peppers) may also increase the permeability of the intestinal lining.10,11

See: Low FODMAP Diet For Irritable Bowel Syndrome IBS Relief

Nightshades and Lectins

Some diet "experts" have been sounding alarms about substances found in nightshade vegetables, whole grains, and beans (legumes), such as pinto and garbanzo beans. The seemingly dangerous compounds are lectins.

Lectins are proteins found in most plants. Essentially, they function as defenders of this plant. They're part of an entire group of chemicals naturally found in plants which fend off invaders. There is nothing to fear from nightshade veggies and other lectin-containing foods such as beans. In actuality, these foods are consumed frequently, often daily, by the healthiest, longest-living populations globally.


Adult acne & weight gain

According to some diet experts, lectins are bad for your health. Lectins, these writers insist, incite a kind of chemical warfare in our own bodies that contribute to everything from arthritis, digestive problems, adult acne, high cholesterol, and mind muddiness to weight gain.


Deactivated by cooking

While it's true that some lectins, particularly those found in raw or undercooked beans, can cause some gastrointestinal problems, it is an issue easily avoided with cooking. Lectins become denatured by cooking. Soaking raw, raw beans like black beans overnight and throwing away the water then boil them for 10 to 15 minutes deactivates all of the lectins found in legumes, which can cause GI issues.


No scientific evidence

Moreover, there's nothing in major medical journals to support any claims that lectins are a dietary issue. Do not let quack nutritionists frighten you away from legumes. Beans are super healthy. Data in the PURE Study, which examined the diet and health of 18 populations around the globe, discovered that people who ate more legumes and other lectin-containing entire plant foods were healthier than those eating a diet much lower in lectins. In reality, the PURE Study data indicate that eating more raw fruits and vegetables (which contain more lectins than cooked fruits and vegetables ) was healthier than cooked.


Whole grains

Besides beans, other foods that have a whole lot of lectins include whole grains like corn, wheat, brown rice, and whole wheat, particularly wheat germ. If you are eating a plant-based diet, then you are eating plenty of lectins. In actuality, a diet that is vegetarian, one that is full of whole foods such as nightshade veggies, is a remarkably healthy diet.


Minimal GI issues

Wheat germ is consumed raw or roasted, and its lectins stay intact. And though many vegetables are consumed raw in fairly large quantities, they seem to cause only minimal GI issues, and frequently in people that aren't accustomed to eating them. Lectins can also be found in seeds and nuts such as walnuts, peanuts, sunflower seeds, hazelnuts, and sesame seeds. Other sources of dietary lectins are coffee, chocolate, and a few spices, such as caraway, marjoram,  nutmeg, peppermint, and garlic.


Benefits of lectins

While some of these lectins can escape being denatured, and some do seem to get absorbed. Interestingly, there's evidence that lectins found in wheat and other whole grains may enhance GI health and even possibly reduce some cancers risk if consumed regularly.


See: Are canned beans healthy

Summary

There is no doubt that nightshade vegetables contain many essential nutrients and also have many health benefits. However, animal and test-tube studies have shown that certain compounds present in nightshades may lead to adverse reactions in people, especially those with autoimmune conditions.  If you have an autoimmune condition or you are sensitive to nightshades, then you should include other vegetables and fruits in your diet to ensure that you are eating a nutritious and well-balanced diet.


See: How to heal leaky gut naturally

References

1. Basu, A., & Imrhan, V. (2007). Tomatoes versus lycopene in oxidative stress and carcinogenesis: conclusions from clinical trials. European journal of clinical nutrition, 61(3), 295-303.

2. Riso, P., Visioli, F., Grande, S., Guarnieri, S., Gardana, C., Simonetti, P., & Porrini, M. (2006). Effect of a tomato-based drink on markers of inflammation, immunomodulation, and oxidative stress. Journal of agricultural and food chemistry, 54(7), 2563-2566.

3. Thankachan, P., Walczyk, T., Muthayya, S., Kurpad, A. V., & Hurrell, R. F. (2008). Iron absorption in young Indian women: the interaction of iron status with the influence of tea and ascorbic acid. The American journal of clinical nutrition, 87(4), 881-886.

4. Nutritiondata.self.com. (2020). Potato, baked, flesh and skin, without salt Nutrition Facts & Calories. [online] Available at: https://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2770/2 [Accessed 23 Jan. 2020].

5. Jenkins, D. J., Kendall, C. W., Popovich, D. G., Vidgen, E., Mehling, C. C., Vuksan, V., ... & Corey, P. (2001). Effect of a very-high-fiber vegetable, fruit, and nut diet on serum lipids and colonic function. Metabolism-Clinical and Experimental, 50(4), 494-503.

6. Kaspar, K. L., Park, J. S., Brown, C. R., Mathison, B. D., Navarre, D. A., & Chew, B. P. (2011). Pigmented potato consumption alters oxidative stress and inflammatory damage in men. The Journal of nutrition, 141(1), 108-111.

7. Bischoff, S. C., Barbara, G., Buurman, W., Ockhuizen, T., Schulzke, J. D., Serino, M., ... & Wells, J. M. (2014). Intestinal permeability–a new target for disease prevention and therapy. BMC gastroenterology, 14(1), 189.

8. Patel, B., Schutte, R., Sporns, P., Doyle, J., Jewel, L., & Fedorak, R. N. (2002). Potato glycoalkaloids adversely affect intestinal permeability and aggravate inflammatory bowel disease. Inflammatory bowel diseases, 8(5), 340-346.

9. Iablokov, V., Sydora, B. C., Foshaug, R., Meddings, J., Driedger, D., Churchill, T., & Fedorak, R. N. (2010). Naturally occurring glycoalkaloids in potatoes aggravate intestinal inflammation in two mouse models of inflammatory bowel disease. Digestive diseases and sciences, 55(11), 3078-3085.

10. Carreno-Gomez, B., Woodley, J. F., & Florence, A. T. (1999). Studies on the uptake of tomato lectin nanoparticles in everted gut sacs. International journal of pharmaceutics, 183(1), 7-11.

11. Jensen-Jarolim, E., Gajdzik, L., Haberl, I., Kraft, D., Scheiner, O., & Graf, J. (1998). Hot spices influence permeability of human intestinal epithelial monolayers. The Journal of nutrition, 128(3), 577-581.

12. Victoria Miller, BSc, Andrew Mente, Ph.D., Mahshid Dehghan, Ph.D., Sumathy Rangarajan, MSc, Xiaohe Zhang, MSc, Sumathi Swaminathan, Ph.D. et al., Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study Open AccessPublished: August 29, 2017DOI:https://doi.org/10.1016/S0140-6736(17)32253-5

13. Fikrat I. Abdullaev  Elvira Gonzalez de Mejia Antitumor effect of plant lectins

First published: 07 December 1998 https://doi.org/10.1002/19970504NT6

See: Ayurveda treatments to prevent and reverse Diabetes Mellitus

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