Lactose is a sugar created by the combination of galactose and glucose, it is found primarily in milk (dairy) foods.
At an early age almost everyone has the ability to digest lactose since it is an important source of energy from nursing milk. Later on in life some people lose the ability to digest lactose and suffer from lactose intolerance. Lactose intolerance can lead to cramps, bloating, flatulence, diarrhea, and even nausea.
Foods high in lactose are typically those which contain milk, cheese, butter, or cream. These include infant formula, candies, chocolates, cakes, pies, eggnog, ice-cream, and macaroni and cheese. Below are the top 10 foods highest in lactose, for more, see the extended list of lactose food sources.