Homocysteine 24 August 2009
Homocysteine is a breakdown product of the amino acid methionine which is found in protein. Elevated levels have now been associated with increased risk of heart attacks, strokes, some cancers, diabetes, depression, osteoporosis and Alzheimer’s disease. Normally homocysteine is metabolised to glutathione (an important antioxidant) and SAMe (a nutrient with antidepressant properties) by enzymes controlled by B vitamins. However, if you don’t have adequate levels of the B vitamins, homocysteine is not sufficiently metabolised and levels rise. Of course, levels of glutathione and SAMe unfortunately decrease. Homocysteine causes damage by:
- inflaming blood vessels resulting in heart attacks and strokes
- damaging DNA increasing the risk of breast and colon cancer and leukaemia.
- increasing the oxidation of LDL cholesterol
- decreasing nitric oxide (a hormone secreted by the endothelium of blood vessels to keep blood pressure normal and decrease blood clotting in arteries)
It is estimated that elevated blood homocysteine levels are responsible for approximately 15% of every heart attack and stroke. Studies also show that the higher your homocysteine level is, the higher your risk of Alzheimer’s disease.
Why don’t you hear more about the risk of homocysteine? Probably because reducing levels is easily done with lifestyle changes and B vitamins. Expensive drugs are not needed. Everybody should know what their homocysteine level is. Homocysteine levels over 20 increase coronary risk tenfold. Levels over 10, double the risk for cardiovascular disease. If your level is greater than 11, your risk of stroke is nearly 4 times higher than it would be if your level was less than 7. The lower your level, the better. Aim for a level of less than 7. If your level is greater than 7, methods to decrease it include:
- decrease animal protein intake
- increase vegetable intake
- have garlic daily
- reduce stress
- stop smoking
- take a multivitamin tablet with at least 800 mcg of folic acid, 300 mcg of vitamin B12 and 100 mg of vitamin B6.
- get your homocysteine level retested after 3 months and if it has not improved, take a supplement specifically designed to lower homocysteine which would include higher doses of the above B vitamins as well as trimethylglycine (TMG) and zinc. TMG tablets contain 500mg of TMG. One to 5 tablets are usually sufficient but up to 12 tablets can be taken if high levels of homocysteine persist. Vitamin B6 can be taken up to 800 mg but 100-250 mg is usually enough. Vitamin B12 can be raised to 300-1500 mcg daily. Failure to reduce homocysteine levels with these high dose supplements suggests kidney dysfunction which should be further investigated.
A study reported in the 2004 edition of the Journal of the American Medical Association tested two different vitamin combinations to see what effect they had on homocysteine levels and recurrent strokes. Unfortunately vitamin doses in both combinations were way too low. The low dose group received vitamin B6 0.2 mg, folic acid 20 mcg and vitamin B12 6 mcg. The “high dose group” received vitamin B6 25 mg, folic acid 2500 mcg and vitamin B12 400 mcg. Other studies have suggested that doses of 100 to 1000 mg of vitamin B6 are necessary to lower homocysteine to safe levels.
In the study, the low dose group experienced minimal change in homocysteine levels over two years. The high dose group had a decrease from an average of 13.4 to 11. There was no decrease in the incidence of recurrent strokes between the two groups. All that means, (as expected) is that decreasing homocysteine from 13 to 11 is not particularly helpful.
The other reason the studies failed to demonstrate a reduction in the incidence of stroke is that there are three blood tests which protect the risk of further stroke:
- C-reactive protein
To protect against stroke, it is important that all three be addressed. Much larger doses of the above vitamins may be required to reduce homocysteine to safe levels.