Are Nightshades Dangerous for Your Health?

August 8, 2021 , , ,

In nutrition, it is not uncommon to hear everything and its opposite. So how do you find your way around when one day you hear that you have to eliminate a certain food from your diet, and then the next day it’s the one that you absolutely have to have on your plate? You may have heard that nightshades, also known as “solanaceae”, are dangerous to your health because they contain toxic compounds and it would be better to avoid them. Therefore, should nightshades be eliminated from your diet? And if so, why?

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First of all, what are nightshades?

The solanaceae family includes nearly 100 genera and more than 2,700 species of plants. There are fruits and vegetables industrial plants (tobacco) and many ornamental plants.

Among the fruits and vegetables, many are commonly consumed such as: tomatoes, eggplants, potatoes, peppers, chilis, and goji berries. Many herbs and spices are also derived from these vegetables, including cayenne pepper, chili powder and paprika.

Are nightshades dangerous for your health?

Solanaceae contain certain compounds which are considered toxic, such as lectins and alkaloids, if they are ingested in large quantities. These compounds are present in the plant because they play a protective role against pathogenic bacteria, viruses, and fungi as well as certain predatory insects.

To learn more about lectins, I invite you to read our article on the subject.

The types of alkaloids differ depending on the type of fruit and vegetable and some are more toxic than others. For example, those present in potatoes are more toxic to the human than those in tomatoes.

Consumed in large quantities, alkaloids can cause symptoms such as sweating, nausea, diarrhea, abdominal cramps, headaches, bronchospasms, drowsiness, agitation, tremors, confusion, or vision disturbances.

Several factors can significantly increase the alkaloid content of fruit and vegetables such as: genetics, storage conditions, exposure to light, or bruising during harvesting. It should be noted that these substances are mainly found in the flowers, leaves, sprouts, and skin of fruits and vegetables.

When a food contains high levels of alkaloids, it can have a pronounced bitter taste in the mouth and cause burning sensations.

However, rest assured, solanaceae are regularly consumed by millions of people around the world and poisonings are rare, which suggests that the low concentrations contained in food do not raise concerns.

What do the studies say?

Studies in mice suggest that alkaloids in potatoes have a cytotoxic effect on the cell membrane that can affect intestinal permeability and increase intestinal inflammation in individuals predisposed to inflammatory bowel disease (IBD).

Some blame them for being pro-inflammatory and for being able to worsen the symptoms of people with autoimmune diseases (such as celiac disease, multiple sclerosis and rheumatoid arthritis). This is why some people choose to exclude them from their diet.

However, current scientific knowledge does not allow recommendations to be made in this regard.

Indeed, before nutritional recommendations can be made, more research is needed to know if these conclusions can be transposed to humans and if this can be extended to all solanaceae.

Nightshades, foods that are rich in nutrients!

Fruits and vegetables are excellent sources of vitamins, minerals, antioxidants and fibers, which have many health benefits. It is not for nothing that we recommend filling half of our plate with vegetables and fruits of various colors at each meal and snack.

Here are some good reasons to consume nightshades:

  • Red pepper and tomatoes are rich in vitamin A and C which act as antioxidants in the body and help it fight against viral and bacterial infections, protect the blood vessels linings and thus reduce the risk of atherosclerosis, as well as optimize iron assimilation. Tomatoes also contain lycopene, a very powerful carotenoid that could prevent certain types of cancer and heart disease as well as strengthen immunity.
  • Potatoes are also rich in fiber and nutrients, they contain potassium, vitamin B6 and manganese. Compared to vegetables, potatoes are high in starch, however, they can be part of a balanced diet when consumed in moderation. Prioritize cooking them without frying and avoid adding too much butter and cream. We enjoy them naturally cooked with added herbs.
  • Studies have shown that the consumption of solanaceae, especially peppers, is associated with a lower risk of developing Parkinson’s disease.
  • In addition, it would appear that solanaceae may help lower high cholesterol levels.

Some precautions to take

  • Consume ripe fruits or vegetables because the concentration of alkaloids is lower than when the food is not ripe. And the taste will be better.
  • Remove most of the stalk as this is where the alkaloids are the most concentrated.
  • Remove any damaged part of your fruit and vegetables or that shows signs of rotting or germination.
  • Store your potatoes in a cool, dry place away from the light.
  • Peel your potatoes, in order to eliminate the majority of alkaloids.
  • Consume green tomatoes and products containing them in moderation.
  • Do not consume the stems and leaves of solanaceae.

Note that cooking does not decrease the alkaloid content of food.


In conclusion, excluding nightshades from your diet is not an optimal solution because these foods also contain many nutrients that are essential for health.

If you experience symptoms, digestive or otherwise, that you think might be related to the foods that you consume, or if you suffer from an autoimmune disease, one of your best options is to talk to a dietitian. They will help review your diet with you and can offer modifications aimed at alleviating your symptoms by maximizing food diversity.



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2- Gouvernement du Canada. 2011. «Les glyco-alcaloïdes dans les aliments».  [accessed July 30 2021].

3- Revue médicale Suisse. 2013. «Fruits et légumes : peuvent-ils être dangereux ?» [accessed July 30 2021].

4- Przybylska, S. (2020). Lycopene–a bioactive carotenoid offering multiple health benefits: a review. International Journal of Food Science & Technology, 55(1), 11-32.

5- 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.

6- 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.

7- Fasano, A., & Shea-Donohue, T. (2005). Mechanisms of disease: the role of intestinal barrier function in the pathogenesis of gastrointestinal autoimmune diseases. Nature clinical practice Gastroenterology & hepatology, 2(9), 416-422.

8- Arrieta, M. C., Bistritz, L., & Meddings, J. B. (2006). Alterations in intestinal permeability. Gut, 55(10), 1512-1520.

9- Nielsen, S. S., Franklin, G. M., Longstreth, W. T., Swanson, P. D., & Checkoway, H. (2013). Nicotine from edible Solanaceae and risk of Parkinson disease. Annals of neurology, 74(3), 472-477.

10- Dougnon, T. V., Bankolé, H. S., Klotoé, J. R., Sènou, M., Fah, L., Koudokpon, H., … & Boko, M. (2014). Treatment of hypercholesterolemia: screening of Solanum macrocarpon Linn (Solanaceae) as a medicinal plant in Benin. Avicenna journal of phytomedicine, 4(3), 160.


Jennifer Morzier
Jennifer is a Registered Dietitian graduated from the University of Montreal in December 2018 and is a member of the Ordre professionnel des diététistes du Québec (OPDQ). She believes that the quality of our food choices has a direct impact on our health and energy level. Her goal? To help people improve the quality of what they put in their plates, for their better well-being and greater pleasure.

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