Homocysteine

Homocysteine

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

Heart

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

133 J.B. Gibson, N. Carson, D.W. Neil: Pathological findings in homocystinuria. J. Clin. Pathol. 17: 427-437, 1964.
134 K.S. McCully: Vascular pathology of homocysteinemia: implications for the pathogenisis of arteriosclerosis. Am. J. Pathol. 56: 111-128, 1969.
135 K.S. McCully: Homocystinuria, arteriosclerosis, methylmalonic aciduria, and methyltransferase deficiency: a key case revisited. Nutr. Rev. 50: 7-12, 1992.
136 A.J. Olszewski and K.S. McCully: Homocysteine metabolism and the oxidative modification of proteins and lipids. Free Rad. Biol. Med. 14: 683-693, 1993.
137 A.J. Olszewski and K.S. McCully: Homocysteine content of lipoproteins in hypercholesterolemia. Atherosclerosis 88: 61-68, 1991.
138 M.J. Stampfer, M.R. Malinow, W.C. Willet, L.M. Newcomer, B. Upson, D. Ullmann, P.V. Tishler and C.H. Hennekens: A prospective study of plasma homocysteine and risk of myocardial infarction in U.S. physicians. JAMA 268: 877-881, 1992.
139 B. Hultberg, E. Agardh, A. Andersson, L. Brattstrom et. al.: Increased levels of plasma homocysteine are associated with nephropathy, but not severe retinopathy in Type 1 diabetes mellitus. Scand. J. Clin. Lab. Invest. 51: 277-282. 1991.
140 J.B. Ubbink, W.J.H. Vermaak, J.M. Bennett, P.J. Becker, D.A. Van Staden and S. Bissbort: The prevalence of homocysteinemia and hypercholesterolemia in angiographically defined coronary heart disease. Klin. Wochenschr. 69: 527-534, 1991.
141 R. Clarke, L. Daly, K. Robinson, et. al.: Hyperhomocysteinemia: an independent risk factor for vascular disease. N. Engl. J. Med. 324: 1149-1155, 1991.
142 J.B. Ubbink, W.J.H. Vermaak, A. Van Der Merwe and P.J. Becker, D.A.: Vitamin B12, vitamin B6, and folate nutritional status in men with hyperhomocysteinemia. Am. J. Clin. Nutr. 57: 47-53, 1993.
143 E. Joosten, A. van den Berg, R. Riezler, H.J. Naurath, J. Lindenbaum, S.P. Stabler and R.H. Allen: Metabolic evidence that deficiencies of vitamin B-12 (cobalamin), folate, and vitamin B-6 occur commonly in elderly people. Am. J. Clin. Nutr. 58: 468-476, 1993.
144 S.A. Kang-Yoon and A. Kirksey: Relation of short-term pyridoxine-HCL supplementation to plasma vitamin B-6 vitamers and amino acid concentrations in young women. Am. J. Clin. Nutr. 55: 865-872, 1992.
145 J.C.W. Brown and J.J. Strain: Effects of dietary homocysteine on copper status in rats. J. Nutr. 120: 1068-1074, 1990.
146 A.J. Olszewski and K.S. McCully: Fish oil decreases serum homocysteine in hyperlipemic men. Coron. Artery Dis. 4: 53-60, 1993.

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