Sunday, August 15, 2010

The Homocysteine Story

As early as 1968, Kilmer McCully, M.D., an observant scientist with training in biochemistry, genetics, and pathology posited that homocysteine was the culprit in the creation of damage to blood vessel walls.

Protein is composed of amino acids. One of these amino acids is methionine. It is an essential amino acid, which means it must be ingested in the food. Methionine is used to create the physical structure of the body, in other words, muscle mass. The body can take methionine and convert it to another essential amino acid called cysteine. Likewise, cysteine can be converted to methionine. However, these biochemical conversions are not straightforward. An intermediary product has to be produced first. Homocysteine is the intermediary product in the interconversion between methionine and cysteine.

Some people have a genetic defect that causes the normal conversion process to go haywire. Consequently, they produce large amounts of homocysteine in the blood and in the urine. Normally, homocysteine is only present in trace amounts in the blood.

A Child with Severe Atherosclerosis. A 9-year old girl with homocystinuria. In describing the medical historyof the family, it was explained that her uncle died at the age of 8 due to a stroke. At autopsy, they found this boy's arteries to be clogged with atherosclerosis, as if he were elderly. That case had been published in the New England Journal of Medicine in 1933 and had referenced the hospital where the study of the case had been undertaken - Massachusetts General Hospital, the place where Dr McCully was employed.McCully went to the archives and confirmed from microscopic slides and small preserved fragments of the organs that the boy did indeed have arteriosclerosis.

What McCully realized in 1968 was that the plaques showed no evidence of cholesterol or fat deposits. He reasoned that homocysteine had caused the damage to the artery wall, but that there had not been enough time for the fat and cholesterol deposits to develop. he later confirmed the same findings in another case of elevated homocysteine in a child. This second case served as proof of his theory that the amino acid homocysteine caused atherosclerosis. But there is more to the story.

As previously stated, the interconversion of methionine to homocysteine to cysteine and back again does not take place in a vacuum. Biochemical processes often require enzymes or cofactors to facilitate the conversion. The cofactors required to convert the toxic substance (homocysteine) to one of its nontoxic counsins (methionine or cysteine ) are the following : vitamin B6, B12, and folic acids. In fact, the genetic defect in the second child McCully studied had a problem with the function of B12.

Folic Acid and B Vitamins
In formulating his theory, McCully recalled the work of pathologist James Rhinehard who had done several experiments on monkeys. Studies in experiments by restricting vitamin B6, vitamin B12 and folic acid showed unequivocally that arteriosclerosis was the result.

How has science missed this important connection? Arteriosclerosis and atherosclerosis were characterized by the Russian pathologist Rudolph Virchow in the 19th century. He noticed the influx of immune cells and proposed the theory that artherosclerosis was the result of some infection, as there were obvious signs of inflammation present. His theory of infection and inflammation is particularly relevant to what we now understand in the role of inflammatory markers such as C-reactive protein (CRP) in predicting artery disease.

Cellular dehydration (water deficit) in your lifestyle also can cause infection and inflammation. Regular and correct amount of water intake is remedy for these causes.

Animal protein is high in methionine, the precursor or artery-damaging homocysteine.

DR.Harry Newburgh did experiments in the 1920s that proved a direct relationship between increasing amounts of dietary protein and increasing atherosclerosis. The more protein he fed the rabbits, the faster they developed artery disease. However, when he was unable to prove that feeding individual amino acids to the rabbits caused atherosclerosis, his theory was abandoned. Unfortunately, two amino acids had not yet been discovered at the time - methionine and homocysteine. Today there are still many substances which we scientists have not discover within our human body. Consequently, the cholesterol myth prevailed.

It was in 1960 that McCully formally proposed his homocysteine theory of heart disease. Although he was almost ostracized by the medical community, he fortunately persisted, and today research studies have proven him correct. An elevated homocysteine is a strong risk factor for heart disease.

What is the relationship between cholesterol and homocysteine?
The same lipoprotein particle that transports cholesterol throughout the human body is also a carrier of homocysteine. This may explain why there is a relationship (even though weak) between markedly elevated cholesterol levels and arteriosclerosis.

Do you know that when after prolonged water deficit within your body system, some cells will be surrounded by cholesterol in order to prevent premature death? It is this water deficit which caused the high blood pressure(to service those cells) and high cholesterol (to prevent premature cell death).

How do we avoid this artery-damaging substance? Two strategies are important. Never take water intake for granted, unless your daily diet is 100% fresh fruits and vegetables. The first is to lower the intake of animal proteins that are high in methionine. The second is to avoid processed foods that are devoid of the vitamins B6, B12 and folic acids (and eat your vegetables!)

What source of protein are high in methionine?
Animal protein. Given that meat is a source of high methionine, then what can we advise about high-protein, low carb diets? It is best to avoid them.

Because the medical community (try asking your doctor) has focused so much attention on the cholesterol myth, proponents of the low-carbohydrate, high-protein diet may seem to have been vindicated. Many stated that a high-protein, low-carb diet would not significantly raise cholesterol levels. The current evidence says that they were right. However, this thinking adheres to the myth that cholesterol is the problem to begin with. If we understand that oxy-cholesterol and homocysteine (and not pure cholesterol per se)are the real instigators of artherosclerosis, then we must take a more scientific view.

Bad News for Low-carb, High-protein Diet!
What happens to the normal function of the cells that create the inner lining of arteries (endothelium) as a result of a low-carbohydrate diet?

26 people were studied using electronic imaging techniques and ulrtrasound scan of the heart and other blood studies. Sixteen of the 26 had a standard low-fat diet. Ten ate a high-protein, low-carbohydrate diet.

After one year patients in the high-protein group showed a worsening of their condition and the markers for artery disease.Specifically, C-reactive protein (CRP) increased 61 percent. Fibrinogen, a substance involved in the clotting process, increased 14 percent. Lipoprotein (a), a type of lipoprotein associated with artery disease, increased 106 percent . The progression of coronary artery disease was documented in each of the vascular territories under study. In the high-protein group there was an overall progression of 39.7 percent . On the other hand, patients in the low-fat diet group had a regression in the extent and severity of their disease as well as improvement in heart muscle function.

Just remember your body need amino acids (found plenty in vegetables and fresh fruits)and not animal protein, to grow its own protein.

The results showed that high-protein diets may precipitate progression of coronary artery disease by increasing inflammation, clot formation, and the deposition of fat on blood vessel walls. Like the rabbits on a high-protein diet, human also risk damage to their human arteries by intentionally taking a high-protein, low-carbohydrate diet. These diet are a large experiment that are proving to be extremely dangerous.

Two harmful substances are present in meat : oxy-cholesterol and high methionine levels.
Methionine can be converted to the injurious homocysteine molecule. One might conclude, then, that a herbivore (fruitarian & vegetarian)would be superior in terms of artery health. In fact, in study after study,fruitarians & vegetarians are clearly found to have better cardiovascular health. You may decide your level of wealth through your health.

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