The investigators propose to conduct a population-based case-control study in Costa Rica to test hypotheses relating dietary intake of specific fatty acids (FA), vitamin E and beta-carotene to risk of coronary heart disease (CHD). Specific associations to be addressed include the relationships between intakes of palm oil, palmitic acid, linoleic acid, trans-isomers of fatty acids, oleic acid, vitamin E, beta-carotene and incidence rate of CHD. Secondary hypotheses to be examined include the relation between intake of vitamin B-6, dietary fiber, body fat and fat distribution and risk of CHD. The Costa Rican population is especially suitable for this study because it is characterized by the following: 1) a range of intake of specific types of fat, especially palm oil, that are of worldwide interest but that cannot be studied in the U.S., 2) a centralized health infrastructure and available census information, and 3) research participation rates over 85%. Case subjects will be 480 residents of a defined geographic region who have been diagnosed as having a myocardial infarction for the first time. Control subjects will be randomly selected using census data from the National Statistics and Census Bureau and matched with the cases for age (+ 5 years), sex, and area of residence. The relationships between dietary FA intake and CHD will be evaluated using a semiquantitative food frequency questionnaire (SFFQ) and analysis of adipose tissue FA composition with capillary column gas-liquid chromatography. Vitamin E and beta-carotene intake will also be assessed by analyses of subcutaneous adipose tissue as well as by the SFFQ. The SFFQ used in this study has been previously used in this population and is predictive of relevant biochemical CHD risk factors. The validity of the SFFQ will be assessed further using seven 24-hour recalls, as well as by comparison with plasma determinations of carotenoid and alpha-tocopherol levels in a subset of 120 controls. Analysis of dietary data will be carried out using stratified and multivariate models, adjusting for significant confounders such as socioeconomic status (SES), cigarette smoking, and body habitus. The investigators state that the findings from this study will provide abundant information on associations between dietary factors and coronary heart disease, and in particular regarding the relation of palm oil and palmitic acid intake to the risk of myocardial infarction, a topic of great debate and economic consequence but for which data have been almost entirely lacking.
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