Magnesium deficiency is one of the most frequently encountered nutritional problems seen clinically. Low magnesium intake is due in large part to the high proportion of nutrient-depleted refined and processed foods in the Western diet. For example, 85% of the magnesium is lost in the refining of whole wheat flour to white flour. Also, studies conducted in the United States and England revealed a 21-35% decline in the magnesium content of fresh fruits and vegetables between the years 1940 and 2000. (Worthington V. Nutritional quality of organic versus conventional fruits, vegetables, and grains. J Altern Complement Med 2001;7:161-173.)
Biochemistry of Magnesium
The adult human body contains 21-28 g of magnesium, about 60% of which is found in bone, 38-39% in cells, and 1-2% in serum and extracellular fluids. Magnesium is the second most abundant cation in soft tissue, behind potassium. Magnesium is a cofactor for more than 300 different enzymes. It is essential for the synthesis of adenosine triphosphate (ATP), the body’s main storage form of energy. In addition, magnesium is involved in a wide range of physiological processes, including neuronal activity, cardiac excitability, and electrical properties of cell membranes. Magnesium inhibits platelet aggregation, promotes dilation of blood vessels, and has an antispasmodic effect on skeletal and smooth muscle. It also plays a role in carbohydrate and lipid metabolism, and in the synthesis of glutathione.
Symptoms of Magnesium Deficiency
Common symptoms of mild to moderate magnesium deficiency may include the following: anxiety, depression, fatigue, insomnia, irritability, panic attacks, muscle cramps and twitches, chest tightness, hyperventilation, faintness, difficulty with mental concentration, memory loss, confusion, headaches, intestinal complaints, tremor, palpitations, and certain types of cardiac arrhythmias. (Durlach J. Clinical aspects of chronic magnesium deficiency. In Magnesium in Health and Disease. New York, Spectrum publications, 1980:883-909.)
Manifestations of more severe magnesium deficiency (in addition to those mentioned above) may include abnormal gait, muscle weakness, vertigo, seizures, hallucinations, electrolyte disturbances (particularly hypokalemia and hypocalcemia), anorexia, myoclonic jerks, nystagmus, stupor, and coma. (Hall RCW, Joffre JR. Hypomagnesemia: physical and psychiatric symptoms. JAMA 1973;224:1749-1751.)
Pathogenic role of magnesium deficiency in ophthalmic diseases
The following paper by Agarwal R, Iezhitsa L, and Agarwal P that was published in 2013 in the Journal Biometals discusses the pathogenic role of magnesium deficiency in ophthalmic diseases. Please see the abstract below and the graphs below that the authors included in their paper:
Magnesium is one of the most important regulatory cation involved in several biological processes. It is important for maintaining the structural and functional integrity of several vital ocular tissues such as cornea, lens and retina. The magnesium content of lens, especially in its peripheral part, is higher than that in aqueous and vitreous humor. Magnesium has also been shown to play critically important role in retinal functions. Magnesium plays significant role as a cofactor for more than 350 enzymes in the body and regulates neuroexcitability and several ion channels. Membrane associated ATPase functions that are crucial in regulating the intracellular ionic environment, are magnesium-dependent. Moreover, the enzymes involved in ATP production and hydrolysis are also magnesium-dependent. Magnesium deficiency by interfering with ATPase functions causes increased intracellular calcium and sodium and decreases intracellular potassium concentration. Such ionic imbalances in turn alter the other cellular enzymatic reactions and form the basis of the association of magnesium deficiency with ophthalmic diseases such as cataract. In presence of magnesium deficiency, an imbalance between mediators of vasoconstriction and vasorelaxation may underlie the vasospasm, which is one of the pathogenic factors in primary open angle glaucoma. Furthermore, magnesium deficiency is also a contributing factor in increased oxidative stress and inducible NOS stimulation that can further contribute in the initiation and progression of ocular pathologies such as cataract, glaucoma and diabetic retinopathy. In this paper we review the association of disturbances of magnesium homeostasis with several ophthalmic diseases.
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