Why have french fries and fried chicken contained trans fats?

French fries and fried chicken have historically contained trans fats because food manufacturers and restaurants adopted hydrogenation to improve the quality and longevity of their products.

By the 1980s, many establishments replaced traditional fats like tallow and lard with trans-fat-based products because they offered similar smoke points and were erroneously believed to be a healthier alternative. Furthermore, hydrogenation transforms liquid vegetable oil into a more stable, semisolid form. This process significantly extended the shelf life of ingredients and provided a stable medium for deep-frying, which was highly valued by the food industry.1

It is important to note that the consumption of manufactured trans fats is linked to serious health risks, including increased LDL cholesterol, heart disease, and stroke. Due to these dangers, many fast-food restaurants have voluntarily moved away from using trans fats in their cooking processes.1