Homocysteine

A heart risk you probably haven't heard of..

Homocysteine, a substance the body normally turns into two amino acids, came into the limelight several years ago. Researchers found some families had a genetic risk for early heart attacks, occurring between 10 and 45 years of age. Some of these heart attack-prone families were discovered to have an enzyme deficiency that created high blood levels of homocysteine.¹³³

Later researchers discovered that homocysteine can directly damage blood vessels and is strongly associated with heart attacks, strokes and peripheral vascular disease.^{134, 135} Homocysteine attaches to LDL and modifies its structure, much like oxidation and glycosylation do. This modification of LDL by homocysteine seems to accelerate heart disease.¹³⁶ One study found that homocysteine levels were four times as high in the LDL of men who had high cholesterol levels compared to those who did not.¹³⁷ In another study of nearly 15,000 physicians, those with unhealthy blood levels of homocysteine were three and a half times more likely to have a heart attack than those with healthy levels.¹³⁸

The hereditary enzyme deficiency mentioned earlier is rare. However, homocysteine levels also rise when B vitamins are low, as they often are in diabetes. Excess urination caused by high blood sugars seems to cause the loss of the water-soluble B vitamins. Homocysteine is found at high levels in most people with diabetes who have kidney disease,¹³⁹ and in 20 to 40 percent of the general population who have heart disease.^{140, 141}

Vitamin B deficiencies also become more likely as we age.¹⁴² One study found a deficiency of one or more B vitamins in 63 percent of healthy Europeans over the age of 65, and in 83 percent of the elderly who were hospitalized for any reason.¹⁴³

A buildup of homocysteine also causes the loss of cysteine, an important antioxidant. In one study, women, ages 20-30, were given a vitamin B-6 supplement, and their cysteine levels rose 50 percent.¹⁴⁴ High levels of homocysteine also lower copper levels in the blood. The activity of some antioxidants depends on copper.¹⁴⁵

Blood levels of homocysteine are easily lowered with a  vitamin B complex supplement. Fish oil has also been shown to decrease homocysteine levels.¹⁴⁶

Bottom Line: A multivitamin supplement containing B vitamins (especially vitamin B6, B12, and folic acid) will keep homocysteine levels lower and may reduce the risk of a heart attack or stroke. This is especially important with any level of kidney disease.

References

Reprinted from Using Insulin by John Walsh, P.A., C.D.E. and Ruth Roberts, M.A. Copyright © 2003, Diabetes Services, Inc.