Magnesium and Taurine in Vascular Protection

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Reference: McCarty MF. Complementary vascular-protective actions of magnesium and taurine: a rationale for magnesium taurate. Med Hypoth 1996; 46:89-100.

Summary: Writing from his office at Nutrition 21 in San Diego, California, the author reviews 136 studies examining the functions of magnesium and taurine in protection of the cardiovascular system. For magnesium, the emphasis is on its intracellular role as a cofactor for the enzymes Na/K-ATPase and Ca-ATPase. Because these transport enzymes undergo decreased function as a result of magnesium deficiency, intracellular concentrations of calcium and sodium may be problematically increased, and potassium concentrations problematically decreased, by magnesium deficiency. The author points out that in many instances where potassium supplementation fails to remedy potassium deficiency, supplemental magnesium may reverse this unwanted outcome.

Extracellularly, magnesium works in much the same way as a calcium channel blocker. High magnesium outside the cell lessens calcium uptake by the cell and results in vasodilation. Conversely low extracellular magnesium can result in vasoconstriction. The author notes that healthy heart muscle cells have significantly higher concentrations of intracellular magnesium than diseased cells.

According to studies cited by the author, humans have a fairly limited capacity for synthesis of taurine from cysteine, resulting in the use of dietary taurine as the major taurine source. In the U.S., daily dietary intake of taurine may be as low as 40 mg or as high as 400 mg.

As with magnesium, one of the physiological roles played by taurine is closely connected to calcium-based signalling mechanisms in the cell and to regulation of calcium homeostasis. Taurine has been shown to promote sarcolemma Ca-ATPase activity, as well as Na/Ca-countertransporter-enzymes which help remove calcium from the interior of the cell and thereby facilitate relaxation of the heart muscle during diastole.

Although studies do not show a direct role for taurine in the neutralizing of reactive oxygen species, they do indicate an ability of taurine to protect the fats in cell membranes from peroxidation. Other cardioprotective aspects of taurine include its ability to reduce the calcium-based response of blood platelets to activating factors, and to suppress sympathetic nervous system activity and reduce the responsiveness of vascular smooth muscle cells to vasoconstricting agents.

The author concludes that both taurine and magnesium act as regulatory molecules which can lessen calcium influx into the cells and enhance the activity of transport proteins which promote calcium efflux. More specifically, a "protein kinsase C hyperresponsiveness syndrome" or "PKC syndrome" is proposed by the author as a fundamental metabolic mechanism partly attributable to our current Western diet and underlying a variety of chronic diseases including hypertension, atherosclerosis, insulin resistance, and certain cancers. In this syndrome, increased intracellular calcium levels increase the activity of protein kinase C enzymes, resulting in excessive vasoconstriction, mitotic signalling, platelet aggregation, cancer promotion, and insulin resistance. The author argues that magnesium taurate makes a logical nutrient combination for helping to restore calcium homeostasis in the above context.

Comments/Opinions: Although the above summary speaks largely for itself, I was particularly interested in the doses of magnesium and taurine reported in Mr. McCarty's review, and the relationship of these doses to food-based intake of magnesium and taurine. In the U.S., we average just under 200 mg of magnesium per day, and between 40-400 mg of taurine, depending on the study cited. By contrast, we average about 600-850 mg of calcium, and as much as 5,000-10,000 mg of other amino acids like phenylalanine. The studies cited in this review article involve magnesium intake at levels approximately twice as high as the U.S. average intake, and taurine levels approximately four times higher.

Achieving research levels of these two nutrients within the context of current U.S. dietary practices will be difficult. To get the World Health Organization's recommended allowance for magnesium, which is about 6 mg/kg/day, most of us would need about 400 mg of magnesium. In terms of food, approximately one cup of almonds or blackstrap molasses (both excellent magnesium sources) would be required to provide that amount. The only more readily available concentrated sources would be sea greens which, in their dried form, average about 175mg/ounce. In case you haven't weighed out an ounce of dried sea greens recently, however, this amount might fall into the category of "gustatorily challenging" for some individuals. Although I've been unable to find reliable data on the taurine content of foods, I am aware of the relative availability of taurine's precursor amino acid, cysteine, in the diet. Approximately one-half cup of wheat germ (or the germ of other grains) would be required to get a 400 mg dose of cysteine. Given some of these dietary realities, the author's argument for magnesium taurate seems even more well-founded.

Natural Product Research Consultants, Inc.

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By B. Levin

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