French fries, in essence, are just potatoes. Cut to variable degrees of thin and thick and fried in hot oil or in the air fryer, any additional ingredients should be limited to seasonings — ranging from classic salt to spicy cajun seasoning. But the french fries from McDonald's tell another story. In the U.S., McDonald's french fries contain more than 10 ingredients, including meat byproducts, wheat, and dairy, listed as follows: Potatoes, vegetable oil (including canola oil, corn oil, soybean oil, and hydrogenated soybean oil), natural beef flavor (containing wheat and milk derivatives), dextrose, sodium acid pyrophosphate, and salt. If you were to visit a McDonald's location in Europe, on the other hand, your fries would only contain four.

McDonald's European menu lists the ingredients of its french fries as potatoes, non-hydrogenated oil (rapeseed in the U.K.; rapeseed or sunflower in Ireland), dextrose, and salt. But even with the dramatically different ingredient lists, McDonald's fries don't look or taste much different in Europe than they do at home. So, what's the point? According to McDonald's, the ingredients in any given menu item in any given country vary depending on things like customer preference and supply chain variability — the same reason why there are different international McDonald's menu items, too. However, another big reason why the fries in particular vary so much is the variation in local food regulations and guidelines between Europe and the U.S.