Soya-derived lecithin is an emulsifier – it is a lipid (fat) which stabilizes foods which contain water and fats, which do not normally mix (which is why you have to shake many salad dressings as they contain oil and water/vinegar which do not mix). For example, lecithin stops the cocoa and cocoa butter in chocolate bars from separating. In addition, lecithin improves the texture of many foods such as chocolate and spreads, and also helps preserves some foods. Since lecithin is a fat, soya lecithin contains very little soya protein, and most people with soya allergy can tolerate it.