Adding linseed oil at 1.5% to 3.5% to layer chicken feed lowers saturated and monounsaturated fats in egg yolks by 15–20% and doubles polyunsaturated fats compared to standard feed.

We analyzed the available evidence and found that adding linseed oil to chicken feed appears to change the fat profile of egg yolks. Specifically, when linseed oil makes up 1.5% to 3.5% of the feed, egg yolks tend to have 15–20% less saturated and monounsaturated fat, while polyunsaturated fats roughly double compared to eggs from hens fed standard diets [1]. This pattern was observed across all 17 studies or assertions we reviewed, with none contradicting it. Linseed oil is rich in a type of polyunsaturated fat called alpha-linolenic acid, which chickens can transfer into their eggs. This means the eggs end up with more of this plant-based omega-3 fat and less of the saturated fats typically found in yolks. We don’t know if this change affects taste, shelf life, or how the body uses these fats — only that the fat composition shifts in a consistent way. The evidence we’ve reviewed so far leans toward this being a reliable effect under these specific feeding conditions. But we haven’t seen long-term data on chicken health, egg production rates, or whether these changes last if the feed is changed back. We also don’t know how much of this fat actually reaches the person eating the egg, or if it makes a meaningful difference to health outcomes. If you’re looking to eat eggs with more polyunsaturated fats and less saturated fat, choosing eggs from hens fed linseed oil may help — but it’s just one factor among many that shape what’s in your food.