The human body requires a small amount of certain fatty acids in order to function properly. Unable to be synthesized from other fats within the body, these essential substances must be obtained from the diet. The most important essential fatty acid is linoleic acid, which is the shortest chain omega-6 fatty acid. Linoleic acid occurs in significant amounts in a number of seed oils and can also be obtained in small quantities from the cell membranes of meats and vegetables. Linoleic acid deficiencies are rare, but are characterized by anemia, scaly skin, decreased healing capabilities, and permeation of fat into the liver. Some studies have indicated that intake of considerable amounts of linoleic acid may help lower the amount of cholesterol in the blood and lessen the propensity for thrombosis.