What are nightshades, and are they problematic for people with endometriosis to include in their diet?

Nightshades refer to a group of over 2000 plants, though most are not eaten by humans. Below is a summary of commonly consumed nightshades:

• Tomatoes

• Goji berries

• Aubergine

• Potatoes

• Peppers

• Jalapeños

• Ashwagandha

While nightshades are not inherently harmful, they may be problematic for individuals with inflammatory or autoimmune conditions. This concern arises from the idea that they might exacerbate pre-existing inflammation in the body. However, it is important to note that they do not directly cause inflammation. This belief is largely anecdotal, and scientific research does not support the idea.

Since people with endometriosis may experience pre-existing inflammation or other inflammatory or autoimmune conditions, they could be sensitive to these foods. Even if the research cannot validate these concerns, it is important to listen to personal experiences, as there may be valuable insights to gain.

Nightshades contain compounds called alkaloids, which are nitrogen-containing substances mainly found in the stems and leaves of these plants. Alkaloids act as natural insect repellents due to their bitter taste and toxicity. This bitterness also discourages humans from consuming certain parts of the plant. While most people can eat nightshades without issue, large doses of alkaloids can be dangerous, though it is unlikely to consume such amounts from normal portions of food. Most people can tolerate dietary alkaloids, but for those who are sensitive, they may cause gastrointestinal symptoms, skin irritation, or joint pain.

Alkaloid levels vary across different parts of the plant and change at various stages of development. This means that the timing of consumption can affect the amount of alkaloids ingested. For example, the skin of a potato is rich in alkaloids, and peeling it before consumption can remove up to 70% of these compounds [1]. For those with sensitivities, peeling the skin may be a practical way to enjoy potatoes. However, potato skins are also packed with nutrients, some of which may have anti-inflammatory properties. Unless adverse symptoms arise, there is no need to avoid them [2]. When potatoes turn green, it indicates a higher alkaloid content, so it may be wise to avoid potatoes that have changed colour or sprouted. In tomatoes, the stem and vine contain more alkaloids than the fruit, which is fortunate since we typically do not consume those parts. Although alkaloids are present in the tomato itself, their levels decrease as the fruit ripens from green to red. Avoiding green tomatoes can help reduce alkaloid intake. Paying attention to these visual cues from food can guide you in making informed dietary choices.

If you are dealing with inflammation and consume a diet high in nightshades, it may be worth eliminating these foods for a couple of weeks to assess any improvements. Upon reintroducing them, observe any symptoms that arise. If your body reacts negatively, it is best to avoid them. However, if you experience no issues, continue to enjoy these nutritious foods. Nightshades offer many health benefits, as they are rich in antioxidants, fibre, and micronutrients.

If you have struggled with nightshades or have seen any difference in removing them from your diet, please leave a comment below.

I posted a couple of polls on my instagram @smart.endo regarding nightshades, here are the results.

References:

1. Rytel E, Tajner‐Czopek A, Aniołowska M, Hamouz K. The influence of dehydrated potatoes processing on the glycoalkaloids content in coloured-fleshed potato. Food Chemistry. 2013;141(3):2495-2500. doi:10.1016/j.foodchem.2013.04.131

   
   

2. Hossain MB, Brunton NP, Dilip K. Effect of drying methods on the steroidal alkaloid content of potato peels, shoots and berries. Molecules. 2016;21(4):403. doi:10.3390/molecules21040403