B12, Homocysteine and Health
Vitamin B12’s position in the upkeep of one’s health is central. Among many of the aspects of health-maintenance B12 helps to control, minimize and flush the levels of an extremely toxic by-product of hormonal metabolism named homocysteine. Recent research has uncovered that a dangerous condition of elevated homocysteine levels can result from even minor B12 depletion. Individuals most at risk for having elevated levels of homocysteine are those who are most in need of vitamin B12 supplementation – vegetarians, individuals nearing middle-age, individuals suffering from poor absorption and unhealthy lifestyles. For all these groups, homocysteine levels soar and remain undisturbed as the body is unable to control and lessen its amounts.
Homocysteine appears to be a nerve and vessel toxin, promoting mortality, cardiovascular disease (CVD), stroke, Alzheimer’s Disease, birth defects, recurrent pregnancy loss, neural tube defects, eye disorders, increased fractures in elderly persons and nerve damage. Cardiovascular disease (CVD) includes Ischemic heart disease (IHD/heart attack), coronary artery disease (CAD/ plaque obstruction of the coronary arteries to the heart), and stroke. An elevated level of blood serum homocysteine is a powerful risk factor for all these issues
Homocysteine auto-oxidizes and reacts with reactive oxygen intermediates and damage endothelial cells (which are extremely important for protection of the blood vessel) and result in a higher risk of forming a thrombus (blood clot). Although homocysteine does not affect bone density, it appears to affects collagen by interfering with the cross-linking between the collagen fibers and the tissues they reinforce. The damage inflicted on these connective tissues results in increased cases of fracture, bone damage and importantly atherosclerosis which is specifically linked to high homocysteine levels.
Diseases which are associated with elevated homocysteine levels are long-term emergent problems. In other words these illnesses occur due prolonged exposure to elevated homocysteine which damages the tissues through its toxicity. In fact, elevated homocysteine levels are a part of aging, whether due to poor absorption in the GI or other reasons. As people are now living longer, the elevated homocysteine has more time to do its damage to the body, thus a spike is noted in illnesses associated with homocysteine levels and aging. Logically everyone should eventually attempt to control their homocysteine levels through B12 supplementation if they wish to lessen the risk of these illnesses
How is homocysteine produced in the body?
Methionine is an essential amino acid involved in hormonal metabolism which is obtained exclusively from ingested protein. In the processes of hormonal metabolism some methionine is turned into homocysteine. The body converts much of the homocysteine back into methionine through an intricate process involving the vitamin B12. If the individual is B12-deficient, homocysteine levels will begin to increase as the reaction of the compounds cannot take place. There are several studies discussing the benefits of B12 supplementation on homocysteine levels and health, and following are several excerpts from these studies.
Medically established normal serum levels of homocysteine range from 2.2 to 13.2 µmol/l. The levels of homocysteine in a typical Western population are around 12 µmol/l. Although this is considered to be within the “normal” range, it is not necessarily healthy.
The analysis of the Oxford Vegetarian Study reported in 2002 showed that overall mortality was the same between vegetarians and non-vegetarians. But vegetarians had 2.2 times the death rate from mental and neurological diseases as non-vegetarians.
The vegetarians had higher homocysteine and lower B12 levels leading to more neurological damage and problems.
Appleby PN, Key TJ, Thorogood M, Burr ML, Mann J. Mortality in British vegetarians. Public Health Nutr. 2002 Feb;5(1):29-36.
11 prospective studies of IHD and 8 of stroke tried to examine and anaylize the effects on health if homocysteine levels were lowered by 25%. The studies involved 9,025 people.
A 25% lower homocysteine level reduced the risk of IHD by 11%, and the risk of stroke by 19%.
In 16 prospective studies of IHD, a 5 µmol/l increase in homocysteine increased the risk of contracting IHD by 23%.
In 8 prospective studies on strokes, a 5 µmol/l increase in homocysteine increased risk of a stroke by 42%.
Homocysteine is better controlled through adequate level of B12, B6 and folate (also known as folic acid). Since vegetarian diets are typically high in folate, the elevated homocysteine levels are normally due to a low B12 intake which, as studies have shown, cannot be viably obtained from ingestion of plant-life. The greater effect of elevated homocysteine on stroke compared to heart disease could explain why vegetarians have not been shown to have lower rates of death from stroke, while they do have lower rates of death from heart disease.
The British Medical Journal published an analysis of 12 studies on the effectiveness of reducing homocysteine levels with folic acid and vitamin B12. They concluded that folic acid in the range of 500-5,000 µg/day reduced homocysteine by 25%, and that B12 supplements (average intake of 500 µg/day) reduced it a further 7%. An addition of B6 did not show any further homocysteine level reduction.