Summary Sesamin, one of the lignans contained in sesame, has been considered to have medicinal effects. It has been reported that sesamin suppressed the development of hypertension in rats. In this study, using a double-blind, cross-over, placebo-controlled trial, we investigated the effect of 4-wk administration of sesamin on blood pressure (BP) in mildly hypertensive humans. Twenty-five middle-aged subjects with mild hypertension were divided into two groups, matched by age and body mass index. Twelve subjects were allocated to 4-wk intake of capsules with 60 mg sesamin per day and 13 subjects to 4-wk intake of a placebo (period 1). After a 4-wk washout period, the subjects received the alternative administration for 4 wk (period 2). BP decreased with statistical significance with the administration of sesamin (systolic: 137.6 Ϯ 2.2 to 134.1 Ϯ 1.7 mmHg, p ϭ 0.044, diastolic: 87.7 Ϯ 1.3 to 85.8 Ϯ 1.0 mmHg, p ϭ 0.045), but little changed with the placebo (systolic: 135.0 Ϯ 1.8 to 135.1 Ϯ 1.7 mmHg, diastolic: 85.9 Ϯ 1.2 to 86.6 Ϯ 1.2 mmHg). In conclusion, 4-wk administration of 60 mg sesamin significantly decreased BP by an average of 3.5 mmHg systolic BP and 1.9 mmHg diastolic BP. These results suggest that sesamin has an antihypertensive effect in humans. Epidemiological studies suggested that a 2-3 mmHg decrease in BP reduces the rate of cardiovascular diseases; therefore, it is considered that BP reduction achieved by sesamin may be meaningful to prevent cardiovascular diseases. Key Words sesamin, hypertension, double-blind, cross-over study, antihypertensive effects Sesame seeds have been commonly used as a traditional health food since ancient times in Asian regions. Sesamin seeds contain not only oil and protein but also characteristic lignans, such as sesamin (0.01-1.0%) and sesamolin. Sesamin is epimerized during acid-clay bleaching in the oil refining process to form episesamin ( Fig. 1) ( 1 ).It seems that sesamin was absorbed via the portal vein in the native form and metabolized to the mono-or di-catechol compound by enzymes in hepatocytes. Both metabolites had antioxidant activity in the liver and were finally conjugated with glucuronic acid by glucuronidase for excretion into bile ( 2 ).Several studies have shown the biological activities of sesamin: anti-oxidative activity ( 2 , 3 ); cholesterol and lipid-lowering ( 4 -8 ); protection against liver damage ( 8 -10 ); synergy with ␣ -tocopherol ( 6 , 11 ) and improvement in the bioavailability of ␥ -tocopherol ( 12 -14 ); anticarcinogenic activities ( 15 , 16 ); and precursors of mammalian lignans ( 17 , 18 ). It has been also reported that sesamin suppressed the development of hypertension in rats ( 2 , 19 -26 ).There are also clinical studies about the effects of sesamin in humans. Hirata et al. ( 5 ) showed that, in males with hypercholesterolemia, oral administration of 9 capsules (each capsule contained 3.6 mg sesamin and 18 mg vitamin E) per day for 4 wk, followed by 18 capsules per day for 4 wk significantly reduced serum total and LDL chole...

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