TY - CHAP M1 - Book, Section TI - Vitamin and Trace Mineral Deficiency and Excess A1 - Suter, Paolo M. A1 - Russell, Robert M. A2 - Jameson, J. Larry A2 - Fauci, Anthony S. A2 - Kasper, Dennis L. A2 - Hauser, Stephen L. A2 - Longo, Dan L. A2 - Loscalzo, Joseph PY - 2018 T2 - Harrison's Principles of Internal Medicine, 20e AB - Vitamins are required constituents of the human diet since they are synthesized inadequately or not at all in the human body. Only small amounts of these substances are needed to carry out essential biochemical reactions (e.g., by acting as coenzymes or prosthetic groups). Overt vitamin or trace mineral deficiencies are rare in Western countries because of a plentiful, varied, and inexpensive food supply; food fortification; and use of supplements. However, multiple nutrient deficiencies may appear together in persons who are chronically ill or alcoholic. After gastric bypass surgery, patients are at high risk for multiple nutrient deficiencies. Moreover, subclinical vitamin and trace mineral deficiencies, as diagnosed by laboratory testing, are quite common in the normal population, especially in the geriatric age group. Conversely, because of the widespread use of nutrient supplements, nutrient toxicities are gaining pathophysiologic and clinical importance. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/10/11 UR - accessmedicine.mhmedical.com/content.aspx?aid=1160015696 ER -