Vitamins are classified as either fat-soluble (lipid soluble) or water-soluble. Vitamins A, D, E and K are lipid-soluble and accumulate within the fat stores of the body and within the liver.The lipid-soluble vitamins are often associated with toxicity when taken in large amounts.itamins are classified as either fat-soluble (lipid soluble) or water-soluble. Vitamins A, D, E and K are lipid-soluble and accumulate within the fat stores of the body and within the liver.