Natural sugars are found in fruit as fructose and in dairy products, such as milk and cheese, as lactose. Foods with natural sugar have an important role in the diet of cancer patients and anyone trying to prevent cancer because they provide essential nutrients that keep the body healthy and help prevent disease.ut the effect on the body and your overall health depends on the type of sugar you’re eating, either natural or refined. We wanted to explore the difference between these sugar types as a follow-up to our post about whether sugar drives the growth of cancer, which has received several comments.