Numerous epidemiologic investigations have found an association between moderate intake of alcohol and increased blood pressure (BP). However, in controlled clinical studies that directly tested the effects of alcohol intake on BP, findings are inconsistent, perhaps because of differences in duration of alcohol use and the timing of BP measurements. In this setting, we performed a systematic review of trials that measured BP after a period of sustained alcohol intake (defined as daily intake of at least one alcoholic drink daily) in one group and that also had a control group of individuals who consumed no alcohol. Nine studies met the entrance criteria. The review demonstrated a significant rise in systolic blood pressure (SBP) and diastolic BP (DBP) of 2.7 mm and 1.4 mm Hg, respectively, after alcohol intake. An early effect of alcohol leading to a reduction BP (in the hours after exposure) and a later effect (next day) of raising BP led to smaller differences in the net effect of alcohol on BP when ambulatory BP monitoring measurements were compared with casual office- or clinic-based measurements. Our findings may have important implications for interpreting studies measuring the effect of alcohol on BP as well as for regular clinical care. These findings indicate that the timing of BP measurements after alcohol intake has a substantial effect on the magnitude and perhaps even the direction of BP change.

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The literature on salt intake and insulin sensitivity presents a mixed picture, as some studies have shown an increase, whereas others have shown a decrease, in insulin action as sodium intake is enhanced. In some cases, this may relate to the study of salt intake in patients with co-morbidities such as hypertension or diabetes. In the present study, we selected healthy normotensive lean volunteers who underwent a euglycaemic clamp following 6 days of a low-salt diet (20 mmol sodium daily) and, subsequently, 6 days of a high-salt diet (200 mmol sodium daily). Our results show an increase in insulin-mediated glucose disposal during euglycaemic clamp conditions that was significantly higher following the high-salt diet compared with the low-salt diet (7.41+/-0.41 compared with 6.11+/-0.40 mg x kg(-1) of body weight x min(-1) respectively; P=0.03). We measured calf blood flow before and during insulin infusion (no significant change after the two dietary salt interventions was detected) and plasma non-esterified fatty acids (also no significant differences were detected). We observed the expected increases in renin concentration and aldosterone activity in subjects on the low-salt diet, and also observed a significantly less increase in plasma noradrenaline concentration during euglycaemic insulin infusion following the high-salt compared with the low-salt diet. We propose that the 4-5-fold increase in serum aldosterone and the greater increase in plasma noradrenaline concentration following the low-salt intervention compared with the high-salt period may have contributed to the differences in insulin sensitivity following the adjustment in dietary sodium intake.