Alkaloids are chemicals that plants produce to protect themselves from pests. This is one reason why people can react to nightshade plants like tomatoes, eggplants and chilli.
Like alkaloids, salicylates are made by plants to defend themselves from insects and disease. Salicylates can be a problem in people who have an impaired ability to digest and excrete them properly.
Amines (like histamine) are formed when certain foods ripen or age. They can cause allergy-like symptoms in sensitive individuals who cannot effectively metabolise them.
Oxalates are naturally found in plants and are made by your body. Having too many oxalates in the body can draw out minerals, like calcium, and lead to issues like painful urination and kidney stones.
- Insoluble fibre and FODMAP sugars
Some vegetables contain fibres and sugars (called FODMAPs) that are not easily broken down in the gut. This can lead to digestive symptoms like gas and bloating and contribute to irritable bowel syndrome symptoms (IBS).