Abstract
Basic principles of Japanese dietary reference intakes (DRIs) published in 2005 for saturated fatty acids are described in detail and evidence tables used for their establishment are presented. Increased intake of saturated fatty acids leads to increased incidences of obesity, diabetes, and myocardial infarction, whereas decreased intake leads to an increased incidence of brain (intraparenchymal) hemorrhage. Therefore, the tentative dietary goal (DG) for saturated fatty acids in individuals more than 18 years of age was set between 4.5% and 7% energy. Obesity due to increased intake of saturated fatty acids eventually causes diabetes, and an increase in saturated fatty acids leads to an increase in LDL-cholesterol concentration that eventually causes myocardial infarction. Many intervention studies have indicated that diets in which saturated fatty acids account for less than 10% energy (NCEP step I diet) or 7% energy (NCEP step II diet) effectively reduce LDL-cholesterol concentration and obesity. Large-scale observation studies have indicated that increased intake of saturated fatty acid or habits to eat more saturated fatty acids may lead to increased dose-dependent incidences of diabetes and myocardial infraction. Median intake of saturated fatty acids in Japanese more than 18 years of age in 2001 was 4.9-7.2% energy in males and 5.4-7.9% energy in females. Considering current saturated fatty acid intakes in Japanese and the dose-dependent effects of saturated fatty acids on the incidence of diabetes and myocardial infarction, the upper limit of saturated fatty acid intake was set at 7% energy. Observation studies targeting Japanese populations have indicated that a lower intake of saturated fatty acids increases the incidence of brain hemorrhage. One study has shown that middle-aged Japanese individuals who had a lower intake of saturated fatty acids had a dose-dependently increased incidence of intraparenchymal hemorrhage, after consideration of confounding factors such as blood pressure, BMI, blood cholesterol, smoking and alcohol consumption. In another study, Japanese living in Hawaii who ate less that 10 g/day saturated fatty acid had a 2-fold increased incidence of stroke. Considering these two studies, the lower intake limit for saturated fatty acids was set at 4.5% energy.
