A Preliminary Study of Potential Dietary Risk Factors for Coronary Heart Disease among Chinese American Adolescents

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Coronary heart disease (CHD) is the leading killer in the United States. Some 570,000 premature deaths occur each year from CHD. Approximately half of Americans older than age 65 have CHD, most commonly, CHD with or without hypertension. The incidence of CHD progressively increases after age 35. However, modifiable risk factors such as low levels of plasma HDL cholesterol, and elevated levels of plasma total and LDL cholesterol, probably are more important than age alone in the etiology of CHD.[1] Compelling scientific evidence supports the view that serum total cholesterol and LDL concentration are the most important factors in determining risk of CHD, with level of risk rising progressively with increasing levels of cholesterol.[2] For population in which the mean serum cholesterol concentration is relatively high, such as in North America, prospective observational studies indicate a strong, direct association between serum cholesterol concentration and CHD.[3]

CHD is one of the diseases associated with affluence. It is more prevalent in population with a high standard of living than in those with a low standard. This difference is reflected in the higher prevalence of CHD in countries where diets include more meat, milk, and fat. The current view suggests that dietary fat, especially saturated fat, is the dietary cause of CHD.[4] Diets high in energy density, total fat, saturated fatty acids, and cholesterol, and low in the ratio of polyunsaturated to saturated fatty acids (P:S), are associated with increased plasma lipids, total cholesterol, triglycerides, and LDL cholesterol and an increase in severity of susceptibility to CHD. Diets low in energy density, fat, and cholesterol and high in polyunsaturated fatty acids (PUFAS) are thought to be protective against CHD.[5]

International comparisons indicate that occurrence of CHD varies greatly from one country to another. In China, the incidence of and mortality from CHD is low, as shown by the World Health Organization (WHO) project on monitoring trends and determinants in cardiovascular disease (MOMICA). The highest age standardized CHD mortality in men ages 35-64 was found in the Siberian MONICA study (401/100,000) and the lowest in the Sino MONICA Beijing study (40/100,000). In women, the highest CHD mortality was found in the Glasgow MONICA study (132/100,000), whereas in Beijing it was only 28/100,000. These 10-fold differences in men and 4.7-fold differences in women may be explained by different levels of CHD risk factors such as dietary habit.[6]

The age adjusted rate for heart disease death in China in 1986 was 28% compared to 37% in U.S., and the mortality rate of CHD in China in 1986 was 6% compared to 16% in U.S.[7] Results of dietary surveys of population subsamples showed that the diet of the Chinese population had the common characteristics of a high carbohydrate content, mainly from starch, and a relatively low fat content, which made up 18% to 31% of total caloric intake. The proportion of saturated fat was low, only 19% of total fat. The diet of North American men contained a considerably higher percentage (40%) of energy from fat, with a high proportion (37%) of saturated fat. Mean daily intake of cholesterol was 300 mg in Chinese men, while a distinctly higher intake of up to 500 mg or more was found for U.S. men.[7]

Asians generally have a lower incidence of CHD than Americans. However, CHD is the leading cause of death for Asian Americans. The incidence of and mortality from CHD appears to increase as Asians migrate from their countries of origin to the U.S. In performing a CHD risk factor and cholesterol screening in an ethnic community in New York City, supporting data suggest the influence of environment on mean total serum cholesterol is important. Chinese living in New York City's Chinatown district have a higher level of total cholesterol than would be expected from studies of Chinese living in China.[8] Dietary changes can alter total cholesterol level in as little as three-four weeks in patients eating the usual American diet who are then placed on a cholesterol-free diet. …