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Taurine supplements lower oxidative stress and improve heart function in iron-overloaded mice
A study published in the April 20 2004 issue of the journal Circulation reported that administration of the amino acid taurine reduced the cardiovascular effects of iron overload in mice. Secondary iron overload and hereditary hemochromatosis have become recognized as widespread, and are associated with increased mortality from cardiovascular disease. In these conditions, iron is deposited in a variety of tissues, including the heart. Because iron overload is associated with increased free radical production, researchers have endeavored to find therapies that minimize the oxidative damage that occurs. The amino acid taurine is found in high concentrations in the heart muscle, accounting for approximately one-fourth of the free amino acid pool in the human heart. Taurine has potent antioxidant properties and has been found to be associated with dilated cardiomyopathy when deficient.
Researchers from the University of Toronto injected two groups of mice with iron for either four or thirteen weeks to create iron overload, and injected another group with a placebo. Two weeks before receiving the iron the mice received either taurine or a placebo in their drinking water, and were continued on these regimens until the end of the study.
Mice who were injected with iron exhibited signs of heart failure, including peripheral edema, lethargy, and increased mortality. Malondialdehyde and other markers of oxidative stress were increased in the myocardium of this group, and glutathione levels decreased. In iron-overloaded mice who received taurine, mortality was reduced compared to those who did not receive the amino acid. Cardiac function, heart rate and blood pressure were improved in the iron-overloaded mice who received taurine and markers of oxidative stress reduced. Taurine supplements completely prevented the decrease of glutathione that occurred in nonsupplemented iron-overloaded mice. When the hearts of the animals were examined, those who received taurine were found to have reduced myocardial iron levels compared to the mice who received iron without taurine.
The authors conclude that in this mouse model of iron-overload, “taurine supplementation has unequivocal beneficial effects on survival and cardiac structure and function, with marked reductions in iron-induced oxidative stress. Given the impressive benefit and absence of toxicity with taurine supplementation, we propose that increased dietary taurine intake represents an important nutritional modification that may prove to be a useful intervention to reduce the worldwide burden from iron-overload cardiovascular disease.” (Oudit GY et al, “Taurine supplementation reduces oxidative stress and improves cardiovascular function in an iron-overload murine model, Circulation, April 20 2004 p 1877-1885.)
Hemochromatosis is a genetic disease of abnormal iron metabolism. A person who has hemochromatosis absorbs too much iron from an ordinary diet. Consequently, this condition is sometimes called "iron overload" or "iron storage overload." If untreated, hemochromatosis can damage major organs in the body (Roeckel et al. 1998). Iron is a catalyst for the generation of free radical activity that has been identified as an underlying cause of cancer, atherosclerosis, liver cirrhosis, neurological disease, and other aging-related disorders. Approximately 32 million Americans are carriers for hemochromatosis, but only a minority of these carriers actually manifests the disease.
Although incidence by this means is rare, hemochromatosis can be acquired from massive doses of iron supplements or from blood transfusions. Far more common is the genetic form of the disease. Genetic hemochromatosis (GH) is also known as hereditary hemochromatosis (HH) and can be detected through screening (Ramrakhiani et al. 1998).
Iron is a catalyst for many enzymatic reactions as well as for massive free-radical damage to cells. Because hemochromatosis patients have chronic high iron levels, they are at risk for a host of free-radical-generated diseases, including cancer and heart disease. Therefore, it is crucial to inhibit these free radicals by consuming large amounts of antioxidants on a regular basis (Last 1991).
Iron-overload disease causes severe depletion of liver glutathione. Glutathione is an important antioxidant, and its depletion in iron overload causes additional free-radical damage. (It should be noted that copper overload induces free radical-induced damage that is similar to iron overload.)
We therefore recommend that hemochromatosis patients take the following in divided doses 2 or 3 times a day with meals:
- 400 IU of vitamin E (alpha tocopherol) with at least 200 mg of gamma tocopherol
- 200 mcg of selenium
- Complete vitamin B complex
- 800 mcg of folic acid
- 30 mg of zinc
- 300 mg of grape seed-skin extract
- 120 mg of ginkgo extract
- 1000 mg of aged garlic extract
- 500 mg of alpha-lipoic acid
- 60 mg of palm-oil tocotrienols
- 600 mg of N-acetyl-cysteine (NAC)
- 300 mg of elemental calcium with each meal
- 500 mg of elemental magnesium
- 500 mg of a silymarin extract containing a high percentage of silbinin
- 1200 mg of a green tea extract (95%) with most meals
- In addition, patients should take 300 mcg-3 mg of melatonin at bedtime.
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Taurine is a conditionally essential amino acid produced from cysteine by the body and found abundantly in the body, particularly throughout the excitable tissues of the central nervous system, where it is thought to have a regulating influence.
L-cysteine is a conditionally essential amino acid, one of only three sulfur-containing amino acids, the others being taurine (which can be produced from L-cysteine) and L-methionine from which L-cysteine can be produced in the body by a multi-step process. Cysteine plays a role in the sulfation cycle, acting as a sulfur donor in phase II detoxification and as a methyl donor in the conversion of homocysteine to methionine. Cysteine also helps synthesize glutathione, one of the body's most important natural detoxifiers. N-acetyl-cysteine is the acetylated form of L-cysteine, which is more efficiently absorbed and used.
Glutathione (gamma-L-glutamyl-L-cysteinyl-glycine) is a peptide (short protein)-like molecule synthesized in the body from the three amino acids L-glutamic acid, L-cysteine, and glycine. Glutathione is one of the body's most important and powerful antioxidants, helping to detoxify xenobiotics.
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