Homocysteine is an amino acid which the body makes from another amino acid called methionine. Methionine is obtained through protein-rich foods like meats seafood, dairy products and eggs.

Ordinarily, homocysteine is converted into two substances called SAMe (S-adenosyl methionine) and glutathione, both of which have benefits to our health. For example, SAMe helps to prevent depression, arthritis and liver damage while glutathione is a powerful antioxidant that helps to slow the ageing process.

The conversion of homocysteine into SAMe requires folic acid, vitamin B12, vitamin B2, zinc, trimethylglycine and magnesium. The conversion of homocysteine to glutathione requires vitamin B6, vitamin B2 and zinc.

When these conversions do not occur properly, the amount of homocysteine in the blood becomes elevated. High levels of homocysteine have been linked with an increased risk of heart disease, vascular disease, dementia and Alzheimer’s disease. Let’s take a look at the evidence.

CARDIOVASCULAR DISEASE

High homocysteine levels have been identified as an independent risk factor for heart disease.1 This is because elevated blood homocysteine levels are thought to be linked with damage to the arteries, causing atherosclerosis (hardening of the arteries). High homocysteine can also cause the blood to have a higher than normal tendency to clot, which leads  to an increased risk of developing a dangerous clot that could lead to a stroke. And, high homocysteine is also known to significantly lower the levels of nitric oxide in the blood. Nitric oxide is essential for the maintenance of healthy and flexible arterial walls.

ALZHEIMER’S DISEASE

High levels of homocysteine have been linked with brain diseases such as Alzheimer’s disease and dementia. Homocysteine is normally converted into the brain chemical acetylcholine, which is used for memory, but studies have shown that Alzheimer’s patients have unusually high levels of homocysteine in their bloodstream and low levels of acetylcholine. A study published in the New England Journal of Medicine in 2002 reported that elevated homocysteine blood levels are an independent risk factor for dementia and Alzheimer’s disease. The researchers found that raised homocysteine levels preceded the onset of dementia in 83 of 111 individuals. Furthermore, the findings showed that the risk of Alzheimer’s disease nearly doubled in individuals who had blood levels of homocysteine greater than 14 μl. per litre.2

REDUCED IMMUNITY

When an inefficient conversion of homocysteine to glutathione leads to a high blood level of homocysteine, the body ends up with fewer levels of glutathione and the antioxidant activity that it provides. With reduced amounts of glutathione and antioxidant activity in the blood, the cells are more susceptible to free radical damage, which accelerates the ageing process and decreases the strength of the immune system.

THE IMPORTANCE OF B VITAMINS

Research suggests that supplementation with B vitamins can help to reduce the body’s levels of homocysteine. Indeed, a 2002 review article in the Journal of the American Medical Association reported that an analysis of multiple studies found that folic acid lowered homocysteine levels by about 25 per cent. When folic acid was combined with vitamin B12, homocysteine levels reduced by a further 7 per cent.3

According to the Linus Pauling Institute, supplementation with vitamins B6, B12 and folic acid, as well as betaine, has been shown to effectively lower homocysteine levels in the blood. One particular report states that “folic acid appears to be useful in most subjects; very high doses of B6 (100 mg or more daily) also seem to have broad utility, whereas lower doses may benefit only those whose baseline B6 status is poor.”4

The report also states that “an additional mechanism for reconverting homocysteine to methionine is provided by the enzyme betaine homocysteine methyltransferase (BHMT).” It explains that intakes of 6g or more daily of betaine have been successfully used to treat genetic homocystinuria (increased levels of homocysteine) in humans.

So, in conclusion, in order to keep your homocysteine levels in check, it is well worth considering supplementing your diet with these vital vitamins.