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Nightshades and Psoriasis

Nightshades and Psoriasis

What are nightshades, why nightshades trigger psoraisis flares and should you avoid them all?

What are nightshades?

It is believed that most nightshades grow better in shady areas and bloom at night so the term “nightshade” may have been coined for these reasons. Nightshades belong to the Solanaceae family, the name Solanaceae derives from the genus Solanum, “the nightshade plant”, the etymology of the Latin word is unclear. Besides few edible nightshades, we are familiar with, there are thousands of inedible plants you may or may not have heard of. Many members of the family contain potent alkaloids, and some are highly toxic. [1]

List of edible nightshades

Bell Peppers
Chilli Peppers
Goji Berries
banana peppers and psoriasis
Banana Peppers
Cayenne Peppers
Ground Cherries

Why nightshades tigger psoriasis flare-ups?

NIghtshades trigger psoriasis and eczema flare-ups, however, this is not the case for everyone, but perhaps for the majority. Some people are highly sensitive and experience red and itchy flare-ups and some experience mild discomfort. So it does affect everyone differently depending on;

  • The severity of Psoriasis
  • Other underlying conditions
  • Lack of digestive enzymes
  • And the way we consume those nightshades; frequency of consumption, method of preparation etc.

The reason for flare-ups could be the components of these fruits and vegetables, for example;

Lectins: Just like gluten, lectins can reduce nutrient absorption, therefore Also known as “antinutrients” they are a type of sugar-binding proteins present in many plant foods and even in some animal products. It is believed that some of these lectins play a role in plant defence against insects. Some studies suggest that lectins in higher amounts can be proinflammatory and can increase intestinal permeability / leaky gut.[2]

Alkaloids: Nightshades contain glycoalkaloids; Αchaconinealso known as conine, belongs to the class of organic compounds known as steroidal saponins (toxic soapy compound) and Solanine is a green-coloured pigmented glycoalkaloid, also known as αsolanine. Glycoalkaloids are usually secondary natural poisonous metabolites produced by plants of the Solanaceae family. It is thought that alkaloids in plants have a function to protect them from the destructive activity of some insect species. They play an important role in plants due to their toxic nature and may have potentially inflammatory effects on people with preexisting inflammatory conditions.[3]

Should you avoid all nightshades if you have psoriasis?

If you notice itching, redness, new psoriasis spots, joint pain, swelling on your fingers and toes after consumption, eliminate nightshades along with other dietary triggers. To understand whether these fruits and veggies are a trigger for you or not, It is worth eliminating them from your diet for a period of one month and see if your skin does any better.

Not everyone is equally sensitive to nightshades. However, since they are known to worsen inflammation in general, it is best to replace them with anti-inflammatory fruits and vegetables.

How to reduce the harm?

After your skin clears up, you can reintroduce nightshades one at a time and see which nightshade you are more sensitive to. Most reported inflammatory nightshades are; Eggplants, Hot peppers and Tomatoes, which is not surprising because they contain the highest solanine and some of them are known as irritants.

According to Dr Gundry, the author of Plant Paradox, who strongly believes that lectins as a major cause of obesity, chronic inflammation, and autoimmune diseases; there is a way to reduce the harm, cooking with high-heat methods like boiling, stewing, or soaking can deactivate most lectins and alkaloids also reduces during cooking. Here are some tips to reduce the harm of most common nightshades:

  • Potatoes:
    • Do not buy green potatoes; The green colour and bitter taste that potatoes can indicate the presence of a toxin.
    • Store potatoes in cool dark areas; When stored in a warm bright place, potatoes produce glycoalkaloids and can turn green.
    • Soak potatoes in cold water overnight; Soaked potatoes make perfect crispy fries and soaking remove the starch and some lectins.
    • Blanch potatoes for three to five minutes before frying, roasting or baking; this will help remove more toxins and whether fried, roasted or baked, blanching potatoes will also guarantee crispiness.
    • Use healthy oils and consume in moderation; Deep-fried foods are a major trigger, so be aware, consume in moderation or avoid, at least during flare-ups.
  • Bell Peppers:
    • Avoid consuming raw peppers; Raw nightshades are higher in toxins, especially bell peppers (capsicum) because the presence of spoilage fungi and the co-occurrence of mycotoxins in the pepper production chain are common.[4]
    • Peel and remove all the seed; It is believed that most toxins are in the seeds and the skin. You can peel the skin by blanching, or grilling over a gas stove or placing it on a hot pan. Once the skin is well grilled, place them in a zip lock bag and let it cool to peel off easily. Peeling peppers this way gives them a smooth texture and deepens the flavour.
  • Tomatoes:
    • Avoid raw green tomatoes; Green tomatoes have higher toxic alkaloid solanine and higher acidity, therefore they are best avoided.
    • Avoid cooked tomatoes; Unlike other nightshades, tomatoes are better uncooked. Some people say they can tolerate fresh tomatoes but not cooked tomatoes. This is true because tomatoes become more acidic during cooking and they can irritate the stomach lining, cause digestive problems as well as psoriasis and eczema flare-ups.
    • Peel and remove all the seeds; Tomato skin and seeds contain the most lectins[5]. Seeds are also known as an irritant to a sensitive stomach and the skin Is indigestible, therefore it is important to peel and deseed tomatoes. The easiest way to peel is to cut an X on the bottom side skin of tomatoes and blanch them for no more than a minute and use the spoon to scoop out all the seeds.
  • Eggplants:
    • Peel and remove the seeds; You can reduce the lectin content of eggplants also by peeling the skin off and removing the seeds. Eggplants seeds tend to hold in most of the bitterness and removing the seeds will help reduce the bitter taste too.
    • Avoid deep-frying; Eggplants’ spongy texture absorbs a surprising amount of oil, and again, deep-fried foods promote inflammation and trigger flare-ups.
    • Salt and wash well; Bitterness and toxins can also be removed with salt and water. Salt the eggplants or soak them in salted water for an hour and wash to remove the excess salt and paper towel dry before cooking.
  • Chilly Peppers:
    • Chilly peppers are best avoided because the capsaicin in chillies can cause inflammation by irritating the lining of the stomach and intestines and so do the seeds, whether it is red or green, chilly seeds can cause irritation and worsen inflammation and this can lead to more flare-ups. However, If you can’t say no to chillies, then note that green chillies are less irritant and more nutritious than red chillies. No matter what type of chilly pepper you choose to consume always remove the seeds.


[1] Gebhardt C. The historical role of species from the Solanaceae plant family in genetic researchTheor Appl Genet. 2016;129(12):2281-2294. doi:10.1007/s00122-016-2804-1

[2] Aristo Vojdani, Daniel Afar, Elroy Vojdani, “Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to Autoimmunity”Journal of Immunology Research, vol. 2020, Article ID 1438957, 16 pages, 2020. https://doi.org/10.1155/2020/1438957

[3] Omayio D. G, Abong G. O, Okoth M. W. A Review of Occurrence of Glycoalkaloids in Potato and Potato Products. Curr Res Nutr Food Sci 2016;4(3). doi : http://dx.doi.org/10.12944/CRNFSJ.4.3.05

[4] Costa, Jéssica et al. “Overview of Fungi and Mycotoxin Contamination in Capsicum Pepper and in Its Derivatives.” Toxins vol. 11,1 27. 8 Jan. 2019, doi:10.3390/toxins11010027

[5] https://gundrymd.com/deseed-tomatoes/ By Gundry MD Team | Aug 27, 2019 

Disclaimer: Dear reader, any and all the content on OffPsoriasis.com Is created for informational purposes only. The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this Website.

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