Though many people are just fine eating as much eggplant as they can, there are some folks that should watch the amount of eggplant they intake. Nasunin is a phytochemical that binds to iron and removes it from cells in a process called iron chelation.
This process, while useful to those who have too much iron in their systems, is dangerous for people with low iron levels. People with iron deficiencies should not consume large amounts of foods that contain nasunin, including eggplant.
Because eggplants belong to the nightshade family, they contain an alkaloid called solanine, which can be toxic if consumed in large amounts. Eating the leaves and tubers of nightshade plants can be fatal, as there are large amounts of the alkaloid in parts of the plant that are not normally consumed.
People are generally at risk of solanine poisoning if they have eaten potatoes that have turned green, as they have the highest amount of solanine in them. Eggplants have a moderate to low amount of solanine and are very unlikely to cause solanine poisoning unless consumed in extremely large amounts that would be impractical for a normal person to be able to eat all at once.
In very rare cases, people can trigger a reaction to one or more of the compounds present in eggplants due to a lipid transfer protein in the plant. These eggplant allergies can cause hives, swelling, and difficulty breathing, and in extreme cases, could lead to anaphylaxis. If anyone experiences any of these symptoms, they should quickly seek medical attention, as anaphylaxis can be a life-threatening allergic reaction.