A stroke happens when the blood supply to the brain is stopped because of a blockage of blood vessel or because of a blood vessel rupture. It deprives the brain tissue of oxygen and nutrients. That causes damages to that brain area. This medical condition affects about four out of 1,000 people, and is the third leading cause of death in most developed countries and the leading cause of disability in adults. Factors predisposing an individual to stroke are high blood pressure, diabetes, high cholesterol and smoking. Recently, another risk factor has generated great interest: homocysteine, a natural compound in the body, derived from dietary proteins. Homocysteine at normal levels does not cause any harm to the body. However, a high level of homocysteine will increase the risk of developing stroke. This trend was observed in a case control study conducted by the European Concerted Action Project, involving a total of 1,550 patients of both sexes younger then 60 years old in nine European countries. "High levels of homocysteine can cause injury and scarring to the lining of the blood vessel wall. Arteries damaged by this process will narrow and may close completely. If this happens to the blood vessel leading to the brain, a stroke will occur," said Dr KS Tan, lecturer in medicine and neurology at the Department of Medicine, Faculty of Medicine, University of Malaya. A study, headed by him in collaboration with the neurology unit at the University of Malaya shows that homocysteine levels in stroke patients was 28 per cent higher when compared to that of normal individuals. Genetic defects or deficiency in certain vitamins may hamper the metabolism of homocysteine to safer by-products and as a result, less homocysteine is removed and more remains in the blood. To maintain normal homocysteine levels, it is recommended to eat foods rich in folic acid, vitamin B6 and vitamin B12. A combination of leafy green vegetables, asparagus, beans, cabbage, non-citrus fruits, poultry and fish are good sources of vitamins B6, B12 and folic acid. A second local study was conducted by University of Malaya on the effectiveness of vitamin B in reducing high homocysteine levels in stroke patients. Dr Tan, a member of the Malaysian Society of Neurosciences and a key researcher of the study, elaborates: "In our study, we recruited patients with borderline or high homocysteine levels. They received six weeks of either one tablet of high potency vitamin B complex containing 0.4mg folic acid, 20mg vitamin B6 and 12-mcg vitamin B12 or a sugar pill." "When compared to patients who were on the sugar pill, there was approximately a 30 per cent reduction in plasma homocysteine levels in these patients." These results are promising as homocysteine levels can now be reduced by consuming foods rich in vitamin B or by adding vitamin B supplements to one's diet as nutritional insurance.