Fat-soluble vitamins, including vitamins A, D, E and K, are molecules with no energy value that are essential for the body to function and for life. Their intake is almost exclusively exogenous, i.e. dietary. As a result, deficiencies in fat-soluble vitamins are rarer in industrialised countries than in countries with limited resources. However, even in the latter, certain groups of individuals are affected, such as newborns or growing children, pregnant or breast-feeding women and elderly or isolated subjects. Vitamin A, D, E and K deficiencies are also relatively common in people with digestive tract disorders, in patients suffering from chronic pathologies or in intensive care patients. Deficiencies or excesses of fat-soluble vitamins are responsible for a variety of more or less specific clinical symptoms. Treatment of deficiencies requires vitamin supplementation, a well-balanced diet and treatment of the cause. [ABSTRACT FROM AUTHOR]