Peanuts and processed peanuts have been demonstrated to be advantageous to health due to their ideal lipid profile, which is richer in unsaturated fatty acids than saturated fatty acids. Peanut oil is trans-fat-free, cholesterol-free, and low in saturated fats by nature. However, the same does not hold true for peanut butter itself. While the oil used to make peanut butter is typically well-hydrated and contains few saturated fats, the protein portion of peanut butter has about 7% fat by weight: mostly oleic acid but also some saturated fatty acids. Peanuts are a legume like soybeans or lentils. Like other beans, they contain high levels of fiber and vitamin B groups. They also provide small amounts of calcium and iron. Eating peanuts can help reduce the risk of developing kidney stones since they are high in fiber and low in sodium. Peanut butter is made from roasted peanuts that are mixed with salt and oil and then pressed or squeezed to remove most of the water content and produce an oil-and-protein paste. The remaining solid material is mixed with sugar or honey as a sweetener and sometimes vanilla or other flavorings are added. Smooth peanut butters have been shown to contain less protein than chunky ones, because the smooth texture allows more exposure to heat during processing. This causes the protein to denature and become insoluble, thus reducing its value as a food source for those who are allergic to peanuts.