Research nurses will screen the medical records and exclude patients who have a history of coronary heart diseases or patients who are taking drugs known to interfere with folic acid, or taking vitamin supplements containing folic acid. Patients will be eligible for inclusion if aged 65 years or more and if their medical histories include two or more of the following conditions: diabetes, hypertension, hyperlipidemia, obesity or smoking. All eligible individuals will receive a letter from the hospital explaining the study, followed by a telephone call inviting them to attend the first visit and instructing them to fast from midnight the night before the visit. At the first visit, all baseline measurements will be taken. Research nurses will take general information, such as, name, age, sex, phone number, address, smoking history, marital status, socioeconomic factors, and the names and phone numbers of two or three friends or relatives who always know how to reach the participants. Drugs history including aspirin or other anticoagulants, antihypertensive, anti-angina, and lipid-lowering drugs will be reviewed. Study procedures will be explained to all subjects. Subjects who are unlikely to complete follow-up due to plans to move or due to disease likely to be fatal within 4 years, or unwilling to participate will be excluded from the study.
Ethics: All subjects will be explained the study protocol, and a written informed consent will ...