Abstract: | Except for a few experimental models of magnesium (Mg)-deficiency-induced neoplasms, less attention has been paid in the past
quarter century in the Western world to this macromineral than to the trace elements; e.g., selenium (Se) and zinc (Zn), and
to vitamins, deficiencies of which are each considered probable factors in oncogenesis. Although early epidemiologic studies
showed an inverse correlation between the amount of Mg in soil and water and the incidence of (gastric) cancer, and several
animal studies supported the premise that Mg has a prophylactic effect against induction of cancer, other studies showed that
Mg supplementation increased the growth of established experimental tumors. Thus, enthusiasm for this approach subsided. The
early epidemiologic findings have since been confirmed, and there have been studies demonstrating the importance of Mg in
maintaining immunocompetence, and others indicating that immunodeficiencies increase susceptibility to the development of
cancer. Evidence has now accrued that indicates that Mg deficiency increases susceptibility to chemical oncogens. The abnormal
metabolism of tryptophan (yielding a carcinogenic metabolite) that indicates functional or absolute pyridoxine deficiency
is an indirect clue to Mg deficiency. Vitamin B6-activated enzymes require Mg as a cofactor. However, the early warnings against the use of Mg as part of an antineoplastic
program against established cancer were justified, since rapidly metabolizing cells (such as cancers) are dependent on Mg.
There are similarities between experiences with Mg and with Se and Zn. All three are required for normal metabolism; Se also
protects against free radicals in the environment. Mg and Zn have increased established tumor growth, and their depletion
has been applied to antineoplastic programs, with risks comparable to those of using antimetabolic agents. |