Oxidative stress was reported to be involved not only in cardiovascular diseases, but also in hypertension. Epidemiologic studies indicated that tea consumption slightly reduces blood pressure. We conducted two studies to determine whether black and green tea can lower blood pressure (BP) in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP (n=15) were allowed to recover for 2 wk after a transmitter for measuring BP was implanted in the peritoneal cavity. The rats were divided into three groups: the control group consumed tap water (30 mL/d); the black tea polyphenol group (BTP) consumed water containing 3.5 g/L thearubigins, 0.6 g/L theaflavins, 0.5 g/L flavonols and 0.4 g/L catechins; and the green tea polyphenol group (GTP) consumed water containing 3.5 g/L catechins, 0.5 g/L flavonols and 1 g/L polymetric flavonoids. The telemetry system was used to measure BP, which were recorded continuously every 5 min for 24 h. During the daytime, systolic and diastolic BP were significantly lower in the BTP and GTP groups than in the controls. Protein expressions of catalase and phosphorylated myosin light chain (MLC-p) were measured in the aorta by Western blotting. GTP significantly increased catalase expression, and BTP and GTP significantly decreased MLC-p expression in the aorta. These data demonstrate that both black and green tea polyphenols attenuate blood pressure increases through their antioxidant properties in SHRSP. Furthermore, because the amounts of polyphenols used in this experiment correspond to those in approximately 1 L of tea, the regular consumption of black and green tea may also provide some protection against hypertension in humans.

1. We showed that a nutritional factor was able to attenuate the development of hypertension and its related diseases in stroke-prone spontaneously hypertensive rats (SHRSP). In the present study, the effect of Wakame, an edible brown seaweed, on the development of stroke was examined in SHRSP. 2. We studied the treatment with 5% (w/w in a diet) Wakame powder in salt-loaded (0.5% NaCl in drinking water) SHRSP. Salt-loaded animals treated with 5% cellulose or kaolin were used as controls. Wakame significantly delayed the development of stroke signs (P < 0.05) and significantly improved the survival rate of salt-loaded SHRSP (P < 0.05). There was no significant difference in the elevation of blood pressure among the three groups during the observation period. 3. We isolated fucoxanthin, a carotinoid, from Wakame powder and studied its preventive effect on ischaemic cultured neuronal cell death. Fucoxanthin significantly attenuated neuronal cell injury in hypoxia and re-oxygenation (P < 0.05). 4. Based on these results, we conclude that Wakame has a beneficial effect on cerebrovascular diseases in SHRSP, independent of hypertension. It is possible that fucoxanthin in Wakame may have a preventive effect against ischaemic neuronal cell death seen in SHRSP with stroke.

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1. Recent studies have identified potential beneficial effects of eating nuts, most of which have substantial amounts of monounsaturated fatty acids (MUFA). Macadamia nuts consist of 75% fat by weight, 80% of which is MUFA (palmitoleic acid). 2. To examine variations in serum lipid levels in response to a high-MUFA diet based on macadamia nuts, 3 week interventions of macadamia nuts, coconuts and butter were determined in young, healthy Japanese female students. 3. After 3 weeks intervention, serum concentrations of total cholesterol and low-density lipoprotein-cholesterol were significantly decreased in the macadamia nut and coconut diets and bodyweight and body mass index were decreased in the group fed macadamia nuts, although there were no statistically significant changes in the group fed butter.