What it is
Lecithin is a fatty substance that works as an emulsifier, holding oil and water together and stopping chocolate from turning grainy. Chemically it is a mixture of phosphatides, the same family of molecules that build the membranes around living cells, which is why it turns up in living things of every kind. The version US regulators describe as generally safe is 'isolated as a gum following hydration of solvent-extracted soy, safflower, or corn oils', in other words squeezed from plants. Nature also packs lecithin into egg yolk, and food makers have pulled it from there for more than a century, so both plant and animal sources are real. When European safety reviewers looked at where E322 actually comes from, they found soya bean oil doing most of the work, with sunflower, rapeseed and egg yolk trailing behind as minor sources.
How to tell
Lecithin turns up in chocolate above almost anything else, then in bread and pastry glazes, margarine, plant milks, ice cream and mayonnaise. Here the law does vegans an accidental favour: soya and egg are both allergens that must be declared in the UK, EU and US, so lecithin from either source is usually spelled out as 'soya lecithin' or 'egg lecithin' rather than hidden. That means a bald 'lecithin' or 'E322' with no allergen warning is very often sunflower, which needs no declaration and is plant-derived. The place to stay alert is baked goods, glossy pastry glazes and some older confectionery recipes, where egg yolk lecithin has a long history. If a label lists only 'lecithin' and you want certainty, check the allergen line for egg, and when it is still unclear a quick message to the maker settles it.
How it is made
Lecithin is a mixture of phospholipids, mostly phosphatidylcholine, found in the cell membranes of plants and animals alike. Commercially it is a byproduct of vegetable oil refining: when crude soybean or sunflower oil is degummed with water, the phospholipids clump out as a thick gum, which is dried into the granules, liquid or powder sold as food-grade lecithin. Because one end of the molecule likes fat and the other likes water, it keeps chocolate, margarine and dressings from separating.
Most lecithin on the market is genuinely plant-derived, and the reason is economics rather than ethics. Soybean and sunflower oil are refined at enormous scale, and lecithin is simply the leftover gum, which makes it cheap and abundant. Egg-derived lecithin is real and is not vegan, but it holds a small specialty share, because pulling phospholipids out of egg yolk costs far more per unit than skimming them off soybean oil. The remaining ambiguity is that a bare lecithin or E322 does not say which.
How to tell
Allergen law narrows this almost to nothing. Soy and egg are both major allergens in the US, the EU and the UK, so soya lecithin and egg lecithin have to be identified as such, usually with a Contains statement or visual emphasis in the ingredient list. Sunflower is not a listed allergen in either system, so sunflower lecithin is named voluntarily. The practical read: a bare lecithin with no soy or egg callout nearby is most likely sunflower, because a manufacturer using soy or egg has a legal reason to say so.
Where egg lecithin genuinely appears is narrower than the internet suggests: some traditional mayonnaise recipes, certain pharmaceutical formulations including injectable lipid emulsions, and some specialty confectionery. It is rare in everyday supermarket packaged food, which is why plain lecithin sits lower on most vegans’ worry list than casein or gelatin.
What the rules say
The FDA lists lecithin as generally recognised as safe and names soy, safflower and corn oils as its sources, which reflects how plant-derived the commercial supply actually is. In the EU, lecithins are approved at quantum satis in most foods, meaning no fixed numerical limit, and the 2017 safety re-evaluation found no basis for setting a numerical acceptable daily intake. Soya lecithin gets no automatic allergen exemption in the EU however refined it is.