It has been discovered recently that the nerve bundles and neurons in the heart contain an abundant supply of glutamate receptors.243 This may explain why some people suddenly die after consuming foods containing large amounts of MSG. Many reports tell of people who eat out at restaurants and an hour later develop crushing chest pain and shortness of breath. Despite all the signs and symptoms of a major heart attack, when they are taken to the emergency room, the ECG may indicate minor abnormalities or, in some cases, severe abnormal heart beats (arrthythmias), but angiograms reveal no problems with the coronary arteries.
By overstimulating the nerves of the heart, MSG could very well induce symptoms similar to a heart attack. Most likely, people suffering from this effect also have low magnesium levels, which would not only make the heart muscle more irritable, but could throw the coronary arteries into spasm, producing a fall blown fatal heart attack. Like the brain, magnesium in the heart prevents the glutamate receptors from over reacting.
Experiments have shown that when animals are fed low magnesium diets and then given a sudden fright, many will die, whereas those fed normal magnesium diets are much more resistant to such sudden death.244 This may explain many of the deaths seen in people caused by sudden shocking events or stress, especially when low magnesium is combined with a high intake of MSG.
Besides the acute danger faced when eating meals high in MSG another less obvious danger exists. Recent studies have found that animals exposed to MSG soon after birth show markedly elevated levels of triglycerides and the very low-density lipoproteins (VLDL) that persist throughout life.245 The values were higher in males than females, ft is now accepted that elevated serum oxidized lipids are associated with an increased risk of heart attack and stroke.
Interestingly, glucose levels in the MSG-treated rats were also markedly elevated, as were insulin levels. This combination—high insulin level along with elevated glucose levels (hyperinsulinemia)—is also found in non-insulin dependent diabetes (type II) in humans. Several studies have confirmed these findings of hyperinsulinemia with MSG exposure.246 Like gross obesity, type II diabetes is also increasing astronomically in children—the very ones who consume the most MSG-containing foods.
High insulin levels combined with hyperinsulinemia, high triglycerides, and hypertension are all symptoms of a newly described disorder called Metabolic Syndrome, a condition that constitutes major risk factors for atherosclerosis, heart attacks, and strokes. So we see that, if the same effects found in test animals also occur in humans, a diet high in MSG-containing foods and snacks would greatly increase the likelihood of a child developing early-onset diabetes and cardiovascular disease—exactly what we are seeing today.
Recent studies have also demonstrated the existence of glutamate receptors on the cells lining arteries in the brain, called endothelial cells, which control calcium entry into the cells. Abnormal functioning of these cells, triggered by excess calcium entry into their interior, is thought to be the central event in the early stages of atherosclerosis. Excess glutamate, derived from the diet, could trigger such calcium flow into the endothelial cell, initiating the events leading up to plaque buildup. Unfortunately, no one has looked at this possibility. If it turns out to be true in humans, MSG in the food supply could be a major contributing factor in atherosclerosis, and so heart attacks, strokes, and peripheral vascular disease.
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