Water-soluble vitamins are found in a wide range of foods, including fruit, vegetables, potatoes, grains, milk and dairy foods.Unlike fat-soluble vitamins, they can be destroyed by heat or being exposed to the air. They can also be lost in water used for cooking.at-soluble vitamins. Fat-soluble vitamins are found mainly in fatty foods and animal products, such as vegetable oils, milk and dairy foods, eggs, liver, oily fish and butter.