Wednesday, April 27, 2011

High Homocysteine - Risk Factor for Alzheimer's Disease


Multiple researches revealed the statistically significant trend, showing that people with high blood levels of homocysteine have at least double than average risk of developing Alzheimer's disease later in life.  Homocysteine is created when the body uses the amino acid, methionine, for methylation.  Normally homocysteine is converted back to methionine, or used to create cysteine and other useful substances.  If these conversions are blocked homocysteine accumulates leading to a host of negative reactions.

Homocysteine, which damages blood vessels, nerves, and specifically mitochondria, has been linked to heart attacks, strokes, cancer (particularly colon, breast, and prostate cancer), Alzheimer's disease and other neurological diseases, depression, birth defects, gout, cervical dysplasia, erectile dysfunction and rheumatoid arthritis.

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What is Homocysteine?

Homocysteine (ho-mo-SIS te-en) is an amino acid (a building block of protein) that is produced in the human body. Homocysteine may irritate blood vessels, leading to blockages in the arteries, called atherosclerosis. High homocysteine levels in the blood can also cause cholesterol to change to something called oxidized lowdensity lipoprotein, which is more damaging to the arteries.

In addition, high homocysteine levels can cause blood clots to form more easily than they should, increasing the risk of blood vessel blockages. A blockage might cause you to have a stroke or a problem with blood flow. Up to 20% of people with heart disease have high homocysteine levels.

Homocysteine is normally changed into other amino acids for use by the body. If your homocysteine level is too high, you may not have enough B vitamins to help this process. Or you may not have enough of the enzymes to process homocysteine.

The B Vitamins Reducing Homocysteine

Efficient conversion of homocysteine requires certain nutrients, which neutralize homocysteine’s toxicity by transforming it into useful substances.  The most well-studies nutrients are folic acid, vitamin B12, and vitamin B6. Choline, betaine (TMG), creatine, riboflavin, zinc, magnesium and other nutrients also help detoxify homocysteine.

Based on the association between elevated homocysteine and Alzheimer’s disease, strategies that lower homocysteine levels to safe ranges, including supplementation with B vitamins, are recommended.

Vitamin B12

Research has suggested that low cobalamin (vitamin B12) levels are related to dementias in general. In a study evaluating levels of vitamin B12 in patients who had Alzheimer’s disease or frontotemporal dementia, researchers found a significant negative correlation (the lower the level of vitamin B12, the more the deterioration) between vitamin B12 and degree of cognitive deterioration. A population-based longitudinal study in Sweden of 370 people aged 75 years or older who did not have dementia found that subjects who had low levels of vitamin B12 or folate had twice the risk of developing Alzheimer’s disease over the 3-year period of the study.

Vitamin B6

A study found significantly lower consumption of vitamin B6 after age 60 years in patients with Alzheimer’s disease compared to control subjects. Low vitamin B6 levels are also associated with elevated numbers of lesions on the brains of patients with Alzheimer’s disease.

Folate (a form of vitamin B9)

Folic acid is needed for DNA synthesis and to make S-adenosylmethionine (SAMe). A study of 126 patients, including 30 who had Alzheimer’s disease, found that the levels of folate in cerebrospinal fluid were significantly lower in patients with late-onset Alzheimer’s disease. Another longitudinal analysis of people between the ages of 70 and 79 years found that people who had high levels of homocysteine or low levels of folate had impaired cognitive function. The strongest association between abnormal levels and dementia was found in people who had low folate levels, leading researchers to suggest that folate might reduce the risk of cognitive decline.

Your Diet

Dr. David Snowden shows in his Kentucky Nuns Study that nuns who were most likely to suffer Alzheimer's disease have low blood levels of the vitamin folic acid and high levels of the protein building block homocysteine. Not eating enough leafy greens and whole grains can deprive you of the vitamin folic acid, and eating too much meat provides you with too much methionine, and the combination of these two factors raises brain levels of homocysteine, that punches holes in arteries and causes plaques to form in them to cause ministrokes, which damages your brain.

Methionine is an essential protein building block that your body uses to make another nonessential building block called cysteine. If you lack any of the three vitamins: B12, folic acid or pyridoxine, methionine is converted to a poison called homocysteine that damages arteries and causes strokes, heart attacks and Alzheimer's disease. Meat is one of the richest sources of methionine, and leafy greens and whole grains are full of folic acid that prevents methionine from being converted to homocysteine. Reducing your intake of meat and poultry lowers your intake of methionine. Folic acid is found everywhere in nature that you get carbohydrates, because folic acid helps your body convert carbohydrates to energy. You can help to prevent Alzheimer's disease by getting folic acid from all whole grains and fortified cereals, leafy green vegetables, beans, seeds, nuts, and many other plants; and by reducing your intake of methionine by eating less meat.

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The amount of vitamin B12 actually needed by the body is very small, probably only about 2 micrograms or 2 millionth of a gram/day. Unfortunately, vitamin B12 is not absorbed very well so much larger amounts need to be supplied through the diet or supplementation. The richest dietary sources of vitamin B12 are liver, especially lamb's liver, and kidneys. Eggs, cheese and some species of fish also supply small amounts, but vegetables and fruits are very poor sources. Several surveys have shown that most strict, long-term vegetarians are vitamin B12 deficient. Many elderly people are also deficient because their production of the intrinsic factor needed to absorb the vitamin from the small intestine decline rapidly with age.

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 Vitamin B6 is found in a wide variety of foods including fortified cereals, beans, meat, poultry, fish, and some fruits and vegetables. The best sources of vitamin B6 include spinach, bell peppers, and turnip greens. Very good food sources of vitamin B6 include garlic, tuna, cauliflower, mustard greens, banana, celery, cabbage, crimini mushrooms, asparagus, broccoli, kale, collard greens, Brussels sprouts, cod and chard.

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Vitamin B Supplements

The usual recommended vitamin and folate doses for lowering homocysteine levels are as follows: a daily multivitamin containing 400 μg of folate and less than 5 mEq of iron. An additional 800 μg of folate per day for 8 weeks. If this does not lower your homocysteine level, you may need a higher dose.

It is important to get your homocysteine level rechecked after you have been taking the multivitamin and folate for 8 weeks. If your homocysteine level remains high, you may need to take more folate (2 mg per day). If you have had a high homocysteine level, you may need to have your level checked later.

Sources and Additional Information:

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