Your Wellness Lifestyle Starts HereI come upon a lot of misinformation about a lot of things and the information regarding nightshade vegetables can be confusing. But what does the evidence say?
Nightshade vegetables are the edible parts of flowering plants and are members of the Solanaceae (solan-acee-ay) family. The nightshade family includes over 2000 plants, most of which are not eaten as food, and some of which, such as belladonna, are poisonous.
Nightshade vegetables include white potatoes, tomatoes, eggplant, bell peppers, Goji berries, tobacco, and tomatillos. Many herbs and spices are derived from nightshades, including cayenne pepper, crushed red pepper, chili powder, and paprika. Several condiments contain nightshades, including hot sauce, ketchup, tomato-based sauces, and salsa.
Nightshade vegetables are staple foods in many cultures, and have been consumed for centuries without side effects. Despite this, some health professionals claim that nightshade vegetables are harmful for people who have certain conditions, and others think that all people should avoid them.
The subject of controversy is nitrogen-containing substances called alkaloids and glycoalkaloids, which are naturally occurring pesticides in these foods. The claim is that they increase inflammation and can cause or worsen conditions like inflammatory bowel disease, rheumatoid arthritis, and other autoimmune diseases. The fact is that many nightshade vegetables contain phytochemicals that have been shown to be anti-inflammatory, rather than pro-inflammatory, such as capsaicin.
Solanine is one of the glycoalkaloids said to be toxic, but studies in both animals and humans have shown that glycoalkaloids/solanine in potatoes are safe, even when consumed in high doses.[1] [2] Some nightshades, like eggplant, peppers, and tomatoes, do not contain any solanine.
A literature search produced no studies definitively showing that consuming nightshade vegetables causes inflammation or disease. A Google search led to newspaper stories[3] and surveys consisting of self-reported data (notoriously unreliable) by doctors who had a personal interest in the topic because they had arthritis themselves.[4]
Dr. Steven Gundry’s comments about nightshades showed up in the google search results. Dr. Gundry says that nightshades are "aptly named because the word implies danger," and that the alkaloids in nightshades "could inspire people throughout history to consider these as evil plants." Note: it’s unlikely that people throughout history knew anything about alkaloids since the technology to identify them did not exist until modern times).
On his site, Dr. Gundry says concern may be warranted because alkaloids include strychnine, caffeine, nicotine, and morphine which have drug-like effects.[5] Gundry’s article includes many statements unsupported by references, and some statements for which there are citations that are irrelevant or misreported. But by far, my favorite comment is his statement that tobacco is not the only nightshade that contains nicotine – many nightshades do. He says this may be one of the reasons why some people become addicted to nightshades and cannot stop eating them – it’s the nicotine!
The bottom line is that there is no research supporting the idea that nightshade vegetables should be avoided. However, sometimes people with conditions like arthritis sometimes identify specific foods to which they are sensitive. These sensitivities are best identified with an elimination diet, which involves eliminating all but a few foods that are well-tolerated by almost everyone and then re-introducing the other foods one at a time to see if symptoms develop. Many members of Wellness Forum Health have been helped with elimination diets, and the results are highly variable. Some people find that there are no foods to which they are sensitive, while others determine that foods that are not usually on the highly suspect list like bananas and black pepper cause problems. In the case of nightshades, few members have discovered a sensitivity to them, and most of those who have discovered a sensitivity have identified one or two foods, not the entire category.
Elimination diets are difficult and time consuming, so it’s best to adopt a health-promoting diet first, and implement an elimination diet only if symptoms do not resolve after a reasonable period of time.
Nightshades are safe to eat for most people but do be careful. According to at least one doctor, they can be addictive. One you start eating them you may not be able to stop. Maybe that's why I crave potatoes?
[1] Mensinga TT, Sips AJ, Rompelberg CJ et al. "Potato glycoalkaloids and adverse events in humans: an ascending dose study." Regul Toxicol Pharmacol 2005 Feb;41(1):66-72.
[2] Phillips BJ, Hughes JA, Phillips JC, Walters DG, Anderson D, Tahourdin CS. "A study of the toxic hazard that might be associated with the consumption of green potato tops." Food Chem Toxicol 1996 May;34(5):439-48
[3] Susannah Meadows "The Boy With a Thorn in His Joints." New York Times Feb 1 2013
[4] Childers NF, Margoles MS. "An Apparent Relation of Nightshades (Solanaceae) to Arthritis." J Neurol Orthoped Med Surg 1993;12:227-231
[5] https://gundrymd.com/nightshade-vegetables/
Nightshade vegetables include white potatoes, tomatoes, eggplant, bell peppers, Goji berries, tobacco, and tomatillos. Many herbs and spices are derived from nightshades, including cayenne pepper, crushed red pepper, chili powder, and paprika. Several condiments contain nightshades, including hot sauce, ketchup, tomato-based sauces, and salsa.
Nightshade vegetables are staple foods in many cultures, and have been consumed for centuries without side effects. Despite this, some health professionals claim that nightshade vegetables are harmful for people who have certain conditions, and others think that all people should avoid them.
The subject of controversy is nitrogen-containing substances called alkaloids and glycoalkaloids, which are naturally occurring pesticides in these foods. The claim is that they increase inflammation and can cause or worsen conditions like inflammatory bowel disease, rheumatoid arthritis, and other autoimmune diseases. The fact is that many nightshade vegetables contain phytochemicals that have been shown to be anti-inflammatory, rather than pro-inflammatory, such as capsaicin.
Solanine is one of the glycoalkaloids said to be toxic, but studies in both animals and humans have shown that glycoalkaloids/solanine in potatoes are safe, even when consumed in high doses.[1] [2] Some nightshades, like eggplant, peppers, and tomatoes, do not contain any solanine.
A literature search produced no studies definitively showing that consuming nightshade vegetables causes inflammation or disease. A Google search led to newspaper stories[3] and surveys consisting of self-reported data (notoriously unreliable) by doctors who had a personal interest in the topic because they had arthritis themselves.[4]
Dr. Steven Gundry’s comments about nightshades showed up in the google search results. Dr. Gundry says that nightshades are "aptly named because the word implies danger," and that the alkaloids in nightshades "could inspire people throughout history to consider these as evil plants." Note: it’s unlikely that people throughout history knew anything about alkaloids since the technology to identify them did not exist until modern times).
On his site, Dr. Gundry says concern may be warranted because alkaloids include strychnine, caffeine, nicotine, and morphine which have drug-like effects.[5] Gundry’s article includes many statements unsupported by references, and some statements for which there are citations that are irrelevant or misreported. But by far, my favorite comment is his statement that tobacco is not the only nightshade that contains nicotine – many nightshades do. He says this may be one of the reasons why some people become addicted to nightshades and cannot stop eating them – it’s the nicotine!
The bottom line is that there is no research supporting the idea that nightshade vegetables should be avoided. However, sometimes people with conditions like arthritis sometimes identify specific foods to which they are sensitive. These sensitivities are best identified with an elimination diet, which involves eliminating all but a few foods that are well-tolerated by almost everyone and then re-introducing the other foods one at a time to see if symptoms develop. Many members of Wellness Forum Health have been helped with elimination diets, and the results are highly variable. Some people find that there are no foods to which they are sensitive, while others determine that foods that are not usually on the highly suspect list like bananas and black pepper cause problems. In the case of nightshades, few members have discovered a sensitivity to them, and most of those who have discovered a sensitivity have identified one or two foods, not the entire category.
Elimination diets are difficult and time consuming, so it’s best to adopt a health-promoting diet first, and implement an elimination diet only if symptoms do not resolve after a reasonable period of time.
Nightshades are safe to eat for most people but do be careful. According to at least one doctor, they can be addictive. One you start eating them you may not be able to stop. Maybe that's why I crave potatoes?
[1] Mensinga TT, Sips AJ, Rompelberg CJ et al. "Potato glycoalkaloids and adverse events in humans: an ascending dose study." Regul Toxicol Pharmacol 2005 Feb;41(1):66-72.
[2] Phillips BJ, Hughes JA, Phillips JC, Walters DG, Anderson D, Tahourdin CS. "A study of the toxic hazard that might be associated with the consumption of green potato tops." Food Chem Toxicol 1996 May;34(5):439-48
[3] Susannah Meadows "The Boy With a Thorn in His Joints." New York Times Feb 1 2013
[4] Childers NF, Margoles MS. "An Apparent Relation of Nightshades (Solanaceae) to Arthritis." J Neurol Orthoped Med Surg 1993;12:227-231
[5] https://gundrymd.com/
Pam Popper, President, Wellness Forum Health
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