Can you get too much?
Except in persons with kidney disease, there is no evidence that large oral
Intakes of magnesium are harmful according to Dr Mansmann. However, people can
Develop diarrhea when they take large quantities of these synthetic forms of the
Mineral; many supplements provide the mineral in the same oxide form that serves
As the basis of common laxatives. Neuroscience Letter 1999 Oct 22;274(2):83-6
Extracellular magnesium regulates effects of vitamin B6, B12 and folate on
Homocysteinemia-induced depletion of intracellular free magnesium ions in canine
Cerebral vascular smooth muscle cells: possible relationship to [Ca2+]i,
Atherogenesis and stroke.
Li W, Zheng T, Wang J, Altura BT, Altura BM Department of Physiology, State
University of New York, Health Science Center at Brooklyn, 11203, USA.
Homocysteine (HC) at concentrations of from 0.05 to 1.0 mm caused
Dose-dependent loss of [Mg2+]i in cultured cerebral vascular smooth muscle cells
(VSMC), whereas cysteine and methionine (its metabolic products) failed to
Interfere with changes in [Mg2+]i. HC, methionine and cysteine did not produce
Any changes in [Ca2+]i.
Lowering [Mg2+]o to 0.3 mm resulted in elevation of [Ca2+]i and loss of[Mg2+]i. Depletion of [Mg2+]i, induced by HC, was potentiated by low Mg2+.
Preincubation of these cells with vitamin B6, vitamin B12, folic acid, alone,
Did not alter [Ca2+]i or [Mg2+]i. Likewise, concomitant addition of vitamin B6,
Vitamin B12, or folic acid, together with HC (1 mm) did not change the reduction
In [Mg2+]i induced by HC.
However, concomitant addition of HC and the three vitamins inhibited
Completely the loss of [Mg2+]i. Exposure of these cells to each vitamin, alone,
Or combination of the three vitamins failed to interfere with reduction in[Mg2+]i induced by low [Mg2+]i, but it did suppress the rise in [Ca2+]i.
Interestingly, in the presence of low [Mg2+]o, the vitamin combination did
Not retard depletion of [Mg2+]i. The present findings are compatible with the
Hypothesis that an increased serum HC concentration causes abnormal metabolism
Of Mg2+ in cerebral VSMC, thus priming these cells for HC-induced atherogenesis,
Cerebral vasospasm and stroke.