Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial.

Regular consumption of green tea may be cardioprotective. In the present study we investigated the health effects of dietary supplementation with green tea catechins and the potential modifying effect of the catechol-O-methyltransferase (COMT) Val/Met genotype. Subjects (sedentary males, aged 40-69 years, with BMI ≥ 28 and ≤ 38 kg/m(2)) were randomly assigned to consume decaffeinated green tea extract (DGT; 530 mg containing about 400 mg total catechins/capsule, twice daily) and placebo in a complete cross-over design. Ambulatory blood pressure and biomarkers of metabolic function (cholesterol, TAG, glucose and insulin) were measured at weeks 0 and 6. Although a marked increase in the concentration of plasma epigallocatechin gallate (EGCG), urinary epigallocatechin (EGC) and urinary 4'-O-methyl EGC was found after DGT treatment, no effect on blood pressure or biomarkers of metabolic function was observed. However, a period × treatment interaction (P < 0·05) was detected for body-weight change. Despite a similar increase in estimated energy intake during intervention period 1, body weight decreased by 0·64 (sd 2·2) kg and increased by 0·53 (sd 1·9) kg in the DGT and placebo groups, respectively (P = 0·025), suggesting a protective effect of green tea catechins on weight gain. Additionally, the COMT Val/Met genotype influenced urinary accumulation of EGC and 4'-O-methyl EGC (P < 0·01). Mean concentrations were lower in individuals homozygous for the high-activity G-allele, possibly reflecting increased metabolic flux and a more rapid conversion to downstream metabolic species, compared with individuals carrying at least one copy of the low-activity A-allele. Additional studies are needed to confirm these findings and further explore the modifying effect of genotype.

Cortisol awakening rise in middle-aged women in relation to psychological stress.

OBJECTIVES: The cortisol awakening rise (CAR) is defined as cortisol secretory activity in the first 45-60 min immediately post-awakening. It has been suggested that psychological factors may disrupt the normal awakening rise. Recent research has shown that psychological stress may influence the magnitude of the CAR, however the findings have been mixed. This study examined the impact of stress on the CAR and the diurnal mean in a sample of middle-aged women. METHOD: One hundred and eighteen healthy female participants who reported experiencing high or low stress were recruited. Salivary cortisol levels were measured immediately upon awakening (at 0, 15, 30, and 45 min) and at 3, 6, 9 and 12 h on two consecutive days. A number of metabolic and inflammatory biomarkers were also assessed together with measures of mood disturbance and health behaviour. RESULTS: The magnitude of the CAR, assessed by the area under the response curve (AURC) estimate, was significantly lower in the high stress group compared to the low stress group indicating that participants who experienced high stress secreted lower levels of cortisol. The effect was largely accounted for by differences 30 min after waking. The diurnal mean was also lower for the high stress group. Although participants in the high stress group had a slightly worse inflammatory profile, only low-density lipoprotein levels were found to be significantly higher, compared to the low stress group. Lifestyle indicators and mood were also found to be significantly poorer in the high stress group. CONCLUSIONS: The results suggest that psychological stress may be associated with a smaller cortisol awakening rise, a lower diurnal mean, poor lifestyle choices and high levels of psychological distress. These findings may have broader implications for future health risk and for an individual's ability to cope with imminent daily stressors and demands.