Stroke and Homocysteine

It has been estimated that in the United States there are at present approximately 1.7 million stroke survivors, 75% of whom are between the ages of 55 and 84. Stroke, which typically refers to an event of blockage of blood supply to a particular part of the brain, represents the third most frequent cause of death in the United States.

Approximately 1/3 of stroke victims do not survive the initial attack. Of those who do, only 10% are able to return to work without disability. Another 40% will experience a mild disability, while an additional 40% are severely disabled. A full 10% of stroke survivors will spend the rest of their lives institutionalized because of their inability to carry out activities of self care.

In the United States, medical expenditures for the care of stroke patients exceeds $30 billion annually. But the emotional impact on patients, their families and caregivers is incalculable.

Homocysteine and Stroke Prevention

“Because of the profound implications of elevated homocysteine, this test should be incorporated into the general physical examination...”

Over the past 30 years there has been a small but certainly meaningful reduction in stroke incidence in this country. No doubt this is due, to some degree, to an increased awareness of, and attention to, several well-recognized risk factors including high blood pressure, cigarette smoking, diabetes, and elevated cholesterol.

But while attention to the role of these medical conditions in increasing susceptibility to stroke is important, recent medical research has identified an even more profound risk factor. Homocysteine, an amino acid generated during the normal course of protein digestion, is now recognized as a critical factor for increasing the risk of stroke as well as coronary artery disease.

Elevation of homocysteine in the blood dramatically increases the production of atheromatous plaque – a mixture of fat and calcified inflammatory tissue that progressively narrows arteries. When the arteries supplying the brain are compromised by this process, the stage is set for the often catastrophic event we know as a stroke.

It is unclear why homocysteine has received so little attention until just the past 5 years. Indeed, its pivotal role in vascular disease was first described over 30 years ago by Dr. Kilmer McCully – research that earned him the 1998 Linus Pauling Award.

Percentage of elderly subjects with extensive arterial narrowing and associated high homocysteine levels. Narrowing of the carotid artery and blood homocysteine levels. From: Selhub, J., et al., N Engl J Med 322(5): 286-291, 1995

Following his landmark publication, other researchers soon discovered a direct relationship between increased homocysteine and stroke risk. In a study regarded as providing the most definitive understanding of the relationship between elevation of homocysteine and stroke risk, researchers at Tufts University measured blood homocysteine levels and the degree of narrowing of the carotid artery (one of the main arteries to the brain) in 1,041 elderly men and women.

Narrowing of the carotid arteries was measured using ultrasound – a noninvasive technique commonly employed in assessing stroke risk. The results clearly indicated a significantly increased risk of extensive arterial narrowing in the subjects with the highest homocysteine levels.

In contrast to elevated cholesterol, hypertension and diabetes, stroke risk factors for which the causes may be obscure, what leads to elevation of homocysteine has now been well defined. Quite simply, homocysteine levels reflect the intake of three important vitamins, B6, B12, and folic acid. Inadequacies of any one or more of these nutrients can enhance homocysteine production, leading to an increased risk of stroke.

Perhaps this explains why the role of homocysteine is not yet generally appreciated by mainstream medicine. For unlike problems with blood pressure, diabetes or cholesterol, the remedy for high homocysteine isn’t provided via the prescription pad. The fix for the problem requires simple and inexpensive vitamin administration.

It has only been in recent years that the powerful role of vitamin supplementation in terms of disease prevention has appeared in the medical literature. In an important study published in the Journal of the American Medical Association in 1993 entitled “Vitamin Status and Intake as Primary Determinants of Homocysteinemia in an Elderly Population,”researchers from Tufts University revealed how widespread deficiencies of vitamins B6, B12 and folic acid in the elderly produce elevated homocysteine and so increase risk of stroke and other vascular problems.

As the authors stated, “... a strong case can be made for prevention of the marginal or manifest vitamin deficiency states that may contribute substantially to this potentially important risk factor for vascular disease, the largest cause of mortality in elderly individuals. Efforts to prevent deficiencies of folate, vitamin B12, and vitamin B6 in the increasing number of our population over the age of 65 years now have added impetus.”

Despite extensive research with frequent medical publications describing the important role of homocysteine in stroke risk, many contemporary physicians remain unaware that a simple blood test for this chemical can not only identify high-risk patients, but may explain why the event occurred. Insist on having a blood test for homocysteine.

Evaluating blood homocysteine is as easy as checking cholesterol. Like the cholesterol test, checking homocysteine requires an overnight fast. Normal values range from 8-14 μmol/L , but a level below 9 should be the goal.

If elevated, homocysteine can almost always be normalized with relatively small amounts of B vitamins. In a recent study of 100 men with elevated homocysteine, supplementation with just 0.65mg of folic acid, 0.4mg vitamin B12, and 10mg of vitamin B6 each day resulted in a reduction of homocysteine by an incredible 50 percent!

Because of the profound implications of elevated homocysteine, this test should be incorporated into the general physical examination of every adult and should be repeated each year. Certainly every stroke patient should be screened for elevated homocysteine as its causal role in stroke is so clearly defined, and its remedy so facile.