Solanaceae—a group of plants that includes tomatoes, potatoes, eggplant, and bell peppers—contain natural compounds called glycoalkaloids (such as solanine and tomatine) that, in high concentrations, can be toxic or cause reactions in sensitive individuals. In the general population, moderate consumption of ripe tomatoes is safe and is part of a balanced diet. However, in certain health contexts, such as psoriasis, arthritis, or other inflammatory conditions, some patients report improvement by temporarily reducing or eliminating these foods.
Recommendations:
1. General population: Ripe red tomatoes can be consumed daily without known risks, since their tomatine content is very low (0.3–6 mg/kg).
2. Avoid unripe green tomatoes: They can contain up to 500 mg/kg of tomatine; frequent consumption is not advisable, especially for sensitive individuals.
3. Potato: Eat well-stored potatoes that are not green, without sprouts, and preferably peeled; discard if they have a bitter taste.
4. People with psoriasis or autoimmune diseases: consider a 3–4-week elimination diet without nightshades, followed by gradual reintroduction, to assess changes in symptoms.
5. Professional supervision: Any prolonged restriction should be guided by a doctor or nutritionist to avoid nutritional deficiencies.
Note: This content is based on food safety reviews and data, as well as studies and reports on nightshades and health. It does not replace medical advice.
Sources cited:
1) Health Canada. *Glycoalkaloids in foods*. Government of Canada. Available at: https://www.canada.ca/en/health-canada/services/food-nutrition/reports-publications/food-safety/glycoalkaloids-foods.html
2) Friedman M. *Tomatine and tomatidine content in tomatoes and tomato products*. Journal of Agricultural and Food Chemistry, 2009. https://doi.org/10.1021/jf900312x
3) National Psoriasis Foundation. *Dietary behaviors and psoriasis: patient-reported outcomes*. J Am Acad Dermatol, 2017;76(3):618–621. https://doi.org/10.1016/j.jaad.2016.10.019
4) EFSA Panel on Contaminants in the Food Chain (CONTAM). *Scientific opinion on glycoalkaloids in food and feed*. EFSA Journal, 2020;18(8):6222. https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2020.6222