P. Rogers

Evidence for a direct effect of alcohol consumption on blood pressure in normotensive men. A randomized controlled trial.

A direct pressor effect of alcohol is proposed as the basis for the association between regular alcohol consumption and an increase in blood pressure found in population studies. To examine this further, a randomized controlled crossover trial of the effects of varying alcohol intake on blood pressure in 46 healthy male drinkers was conducted. From an average of 336 ml of ethanol per week, alcohol consumption was reduced by 80% for 6 weeks by drinking a low alcohol content beer alone. This reduction was associated with a significant reduction in systolic and diastolic blood pressure (p less than 0.001 and p less than 0.05 respectively). The mean difference in supine systolic blood pressure during the last 2 weeks of normal or low alcohol intake was 3.8 mm Hg, which correlated significantly with change in alcohol consumption (r = 0.53, p less than 0.001). Reduction of alcohol intake also caused a significant decrease in weight (p less than 0.001). After adjustment for weight change, an independent effect of alcohol on systolic but not diastolic blood pressure was still evident, with a 3.1 mm Hg fall predicted for a decrease in consumption from 350 ml of ethanol equivalent per week to 70 ml per week (p less than 0.01). Systolic blood pressure rose again when normal drinking habits were resumed. These results provide clear evidence for a direct and reversible pressor effect of regular moderate alcohol consumption in normotensive men and suggest that alcohol may play a major role in the genesis of early stages of blood pressure elevation.

Effects of isoflavonoids on blood pressure in subjects with high-normal ambulatory blood pressure levels: A randomized controlled trial

Vegetarian diets lower blood pressure (BP), but attempts to identify dietary components responsible have been unsuccessful. Isoflavonoids are commonly consumed as part of vegetarian diets. The objective of this study was to assess the effect of isoflavonoid supplementation on BP. Fifty-nine subjects with high-normal range systolic BP completed a randomized, double blind, placebo-controlled trial of two-way parallel design and 8 weeks duration. One tablet containing 55 mg of isoflavonoids, including 30 mg of genistein, 16 mg of biochanin A (a genistein precursor), 1 mg of daidzein, and 8 mg of formononetin (a daidzein precursor), or one placebo tablet, was taken daily with the evening meal. Significant increases in urinary excretion of genistein (5.22 mg/day, 95% CI: 3.72, 6.72) and daidzein (2.53 mg/day, 95% CI: 1.66, 3.40) were observed in the group taking the isoflavonoid supplement. There were no significant changes in isoflavonoid excretion in the placebo group. Clinic BP was measured at two visits, and ambulatory BP monitoring was performed over one 24-h period, at baseline and postintervention. There was no significant difference between groups, after adjustment for baseline values, in postintervention clinic supine BP (systolic 1.2 mm Hg, 95% CI: -2.3, 4.7; diastolic 0.6 mm Hg, 95% CI: -1.9, 2.5), clinic erect BP (systolic 1.7 mm Hg, 95% CI: -4.0, 8.4; diastolic 0.4 mm Hg, 95% CI: -2.4, 3.2), or 24-h ambulatory BP (systolic -1.4 mm Hg, 95% CI: -4.4, 1.6; diastolic -0.8 mm Hg, 95% CI: -2.3, 0.7). Adjustment for age, gender, and weight change did not alter the result. Therefore, these results do not support the hypothesis that isoflavonoids, and genistein in particular, are major contributors to the BP lowering effect of vegetarian diets.

A factorial study of salt restriction and a low-fat/high-fibre diet in hypertensive subjects.

Objective: To compare the independent and additive effects of sodium restriction and a low-fat, high polyunsaturated: saturated fatty acids (P:S) ratio, high-fibre diet upon blood pressure. Design: A randomized, parallet, double-blind, placebo-controlled (for sodium) 2x2 factorial trial. Setting: Clinical. Participants: Ninety-five hypertensive subjects (mean blood pressure, 137/83 mmHg), mean age 53.5 years, consuming<30 ml ethanol/day were selected from community volunteers. Sevevty-nine treated and twelve untreated hypertensives completed the trial. Intervention: Subjects followed either a low-sodium, low-fat/high-fibre diet (<60mmol sodium/day; 30% fat energy; P:S ratio=1; 30-50g fibre/day) or a low-sodium, normal-fat/normal-fibre diet (<60 mmol sodium/day; 40% fat energy; P:S ratio=0.3; 15 g fibre/day) for 8 weeks. Half of each group received 100 mmol/day NaCI and the remainder received placebo. Main outcome measures: Blood pressure and blood lipids. Results: Sodium restriction significantly reduced standing and supine systolic blood pressure, with no effect upon diastolic blood pressure. The low-fat/high-fibre diet had no effect upon blood pressure, but significantly reduced total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. Conclusions: Sodium restriction reduced blood pressure and did not raise low-density lipoprotein cholesterol. A low-fat/high-fibre diet did not reduce blood pressure but lowered cholesterol levels. A combination of the two regimes has the greater potential for reducing cardiovascular risk in hypertensives.

Ambulatory blood pressure and heart rate responses to vegetarian meals.

Objectives: To determine the effects of a vegetarian diet on daytime ambulatory (Accutracker) blood pressures and heart rates, and to relate these to the estimated peak in plasma glucose to determine whether low-glycaemic-index diets reduce sympathetic activity in response to differences in postprandial glucose and insulin. Design: The subjects were matched for age and body mass index and randomly assigned to one of two parallel diet groups. Setting: Clinical. Participants: Twenty-one normotensive non-vegetarian male hospital workers volunteered for the study and 20 completed it. Intervention: After 2 weeks of baseline measurement the subjects followed an omnivorous or a lacto-ovovegetarian diet for 6 weeks. Main outcome measures: Daytime ambulatory blood pressures and heart rate, and postbreakfast catecholamines, insulin and glucose. Results: Ambulatory systolic blood pressure and heart rates were lower in the vegetarian group during the working day. The preprandial rise in diastolic pressure was attenuated on the vegetarian diet. There were no differences in plasma catecholamine, glucose or insulin levels sampled after breakfast on the two dietary regimes. Conclusions: The blood pressure-lowering effect of a lacto-ovovegetarian diet, which occurs throughout the working day, is associated with lower heart rates, suggesting a central nervous or cardiac mechanism. The possibility that the lower glycaemic index of a lacto-ovovegetarian diet has some effect needs to be investigated further in relation to major meal-times and studied in both normotensive and hypertensive subjects.

Potassium supplementation does not lower blood pressure in normotensive women.

Forty-four normotensive females, who were selected on the basis of lower prevailing potassium intake, participated in a two-period crossover study to assess the effects of potassium supplementation on blood pressure. They were randomly allocated to one of two groups who took either 80 mmol/day of KCl (Slow-K, Ciba Geigy), or matching placebo, for the first of two 4-week treatment periods. The treatments were reversed during the second 4-week period. Despite significant increases in both urinary and plasma potassium no consistent fall in blood pressure was seen during 80 mmol/day potassium intake.

COMPARISON OF OSCILLOMETRIC BLOOD PRESSURE MEASUREMENTS AT THE WRIST WITH AN UPPER-ARM AUSCULTATORY MERCURY SPHYGMOMANOMETER

1. Oscillometric devices for blood pressure (BP) measurement at the wrist are becoming more widely used in clinical practice. However, systematic comparisons with standard auscultatory BP measurement at the brachial artery are scarce. Therefore, we compared two such devices, the Boso‐Mediwatch (Bosch & Sohn GmbH U. Co., Jungingen, Germany) and the Omron R3 (Omron Corp., Tokyo, Japan), with upper‐arm auscultatory mercury sphygmomanometry.

Biochemical and neurohormonal responses to the introduction of a lacto-ovovegetarian diet

Objective: To assess the mechanisms of the blood pressure-lowering effect of a vegetarian diet in the early and later stages of dietary intervention Design: After 2 weeks without intervention (baseline), 20 normotensive men were matched for age and body mass index and randomly allocated to an omnivorous (control) or a lacto-ovovegetarian diet for 6 weeks in a parallel trial Methods: Ambulatory blood pressures were recorded between 0800 and 1700 h on alternate days during the first week of intervention, twice in the second week and weekly thereafter. Blood samples collected after a standard breakfast were analysed for plasma noradrenaline, adrenaline, atrial natriuretic peptide (ANP), renin, aldosterone, glucose and insulin. Factor and multiple regression analyses were used to assess the association among neurohormonal factors, blood pressures and diet. Results were analysed for the first week of the diet and for the entire 6 weeks Results: Ambulatory blood pressures at work were lower on the vegetarian diet than in the controls. This blood pressure decrease was associated with a factor representing lower plasma catecholamine and renin activity levels throughout the study, and a factor representing reduced plasma glucose and insulin levels in week 1 of intervention only. Plasma ANP levels were significantly higher during week 1 of the vegetarian diet Conclusions: A blood pressure lowering effect of a vegetarian diet during normal working activity was shown. Using factors derived from the biochemical variables, results were in keeping with the hypothesis that these effects may be mediated by reduced sympatho-adrenal activity consequent to altered glucose and insulin handling. An early increase in plasma ANP may contribute to the blood pressure reduction

The effect of ascorbic acid on plasma sulfate conjugated catecholamines after eating bananas

The effects of eating bananas, a rich source of biogenic amines, on the plasma concentration of free and sulfate conjugated norepinephrine (NE) and dopamine (DA), and free epinephrine (E), were examined in normal male subjects before and after treatment with ascorbic acid, 2 g daily for 7 days. There were no significant changes in the levels of free NE or E in any subjects after eating a banana, either before or after ascorbic acid. Plasma free DA became detectable in some subjects, but the overall changes were not significant. Sulfate conjugated DA and NE increased markedly after banana ingestion, as previously demonstrated in our laboratory. After ascorbic acid treatment the rise in sulfate conjugated NE was attenuated, presumably because ascorbic acid acts as a competitive inhibitor of sulfate conjugation. In contrast, the rise in conjugated DA was potentiated after ascorbic acid treatment. This may be indicative of the higher affinity of DA for phenolsulfotransferase, an inhibitory effect of ascorbic acid on dopamine-receptor coupling or of ascorbic acid protecting DA from oxidation in the gut.