Robert Vandongen

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 alcohol use and other aspects of lifestyle on blood pressure levels and prevalence of hypertension in a working population.

The relationship between alcohol consumption and blood pressure was studied in 491 males, ages 20–45 years, who volunteered to complete a health questionnaire and submit to standardized measurements of blood pressure, heart rate and body size. Average weekly alcohol consumption correlated with systolic pressure (r = 0.18) but not diastolic pressure. Systolic pressure increased progressively with increasing alcohol consumption, with no obvious threshold effect. In moderate and heavy drinkers (53% of the population studied), the prevalence of systolic hypertension (≥ 140 mm Hg) was four times that of teetotalers. The effect of alcohol on systolic blood pressure was independent of the effects of age, obesity, cigarette smoking and physical activity. Ex-heavy drinkers had blood pressures similar to those of teetotalers, suggesting that the effect of alcohol is reversible. Cigarette smokers had lower diastolic pressures than nonsmokers, an effect independent of obesity. The linear correlation between alcohol consumption and systolic blood pressure and the lower blood pressures in exdrinkers suggest a cause-and-effect relationship. The results indicate that alcohol ranks close to obesity as a potentially preventable cause of hypertension in the community.

Vegetarian diet in mild hypertension: a randomised controlled trial.

In a randomised crossover trial 58 subjects aged 30-64 with mild untreated hypertension were allocated either to a control group eating a typical omnivorous diet or to one of two groups eating an ovolactovegetarian diet for one of two six week periods. A fall in systolic blood pressure of the order of 5 mm Hg occurred during the vegetarian diet periods, with a corresponding rise on resuming a meat diet. The main nutrient changes with the vegetarian diet included an increase in the ratio of polyunsaturated to saturated fats and intake of fibre, calcium, and magnesium and a decrease in the intake of protein and vitamin B12. There were no consistent changes in urinary sodium or potassium excretion or body weight. In untreated subjects with mild hypertension, changing to a vegetarian diet may bring about a worthwhile fall in systolic blood pressure.

Effects of alcohol and caloric restrictions on blood pressure and serum lipids in overweight men.

We have examined the independent and combined effects on blood pressure and blood lipids of alcohol restriction and weight loss in overweight male drinkers with a view to assessing overall effects on cardiovascular risk of two widely promoted nonpharmacological approaches for hypertension. Eighty-six men with a mean age of 44.3 years, a mean regular alcohol intake of 440 ml/wk (five or six standard drinks per day), a mean blood pressure of 137.4 mm Hg systolic and 84.8 mm Hg diastolic, and a mean body mass of 92.5 kg entered a controlled two-way factorial study. The subjects were randomly assigned to four groups for an 18-week intervention in which members of two groups drank only low-alcohol beer, thereby reducing their alcohol intake by 374 ml/wk, while those of the other two groups continued their normal alcohol intake. Within the low and normal alcohol intake groups subjects either continued their usual diet or reduced their caloric intake by 4,200-6,300 kJ/day (1,000-1,500 kcal/day) (with protein, fat, and carbohydrate provided as 15%, 30%, and 55% of total calories, respectively). Calorie reduction and alcohol restriction caused weight losses of 7.5 (p less than 0.001) and 2.1 (p less than 0.01) kg, respectively. Calorie reduction and alcohol restriction were associated with decreases in systolic blood pressure of 5.4 (p less than 0.001) and 4.8 (p less than 0.01) mm Hg, respectively, and in diastolic blood pressure of 4.2 (p less than 0.001) and 3.3 (p less than 0.01) mm Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary modification of fatty acid and prostaglandin synthesis in the rat: Effect of variations in the level of dietary fat

Dietary supplements with safflower oil, linseed oil, cod liver oil and hydrogenated coconut oil were given to rats at levels of 5, 20 and 40 energy % to simultaneously assess the effects of both type and level of dietary fat on tissue fatty acid composition and prostanoid synthesis. There was no significant change in weight gain or blood pressure between the dietary groups after the 4-week dietary regimen. The liver oil and linseed oil diets depressed the arachidonic acid content of kidney phospholipids at all levels of supplementation. The arachidonic acid content of plasma lipids was significantly elevated in animals on the safflower oil diet at 20 and 40 energy % while those on the same level of liver oil diet showed a marked reduction in arachidonic acid. Whole blood synthesis of thromboxane B2 varied significantly at all levels of fat supplementation, with the 20 energy % safflower oil fed group showing maximally enhanced thromboxane B2 production compared to the coconut oil group (P less than 0.001). Conversely, the liver oil groups showed depressed thromboxane B2 synthesis at 20 and 40 energy % (P less than 0.01) compared to the coconut oil group and at 5 energy % compared to the safflower oil group (P less than 0.05). Production of 6-ketoprostaglandin F1 alpha and prostaglandin E2 by incubated kidney homogenates only differed significantly between the dietary groups at 40 energy %. Urinary excretion of 6-ketoprostaglandin F1 alpha was increased by 45% and 55% in rats fed the safflower oil diet at 20 and 40 energy %, respectively compared to the saturated fat diet, while in the liver oil groups excretion was reduced by 20% and 32%. Dietary suppression of prostanoid synthesis is explained in part by changes in available arachidonic acid and competitive inhibition of cyclooxygenase by (n - 3) fatty acids. Thus, minor changes in dietary fat can readily alter tissue fatty acid composition, but both the extent and nature of changes in phospholipid and prostanoid metabolism vary markedly according to the tissue site.

The pressor effect of moderate alcohol consumption in man: a search for mechanisms.

Thirty pairs of drinking and nondrinking men, matched for age and weight, were drawn from a working population in which a close relationship between alcohol consumption and blood pressure had been demonstrated. In this smaller sample, men who drank an average of 408 ml of ethanol/week had higher supine (126.9 ± 2.3 mm Hg) and standing (113.3 ± 2.5 mm Hg) systolic and supine diastolic blood pressure (75.5 ± 2.2 mm Hg) than nondrinkers (117.5 ± 2.0, 107.4 ± 2.2 and 68.9 ± 1.8 mm Hg, respectively). Resting plasma concentrations of free and sulfated norepinephrine and epinephrine, renin activity, angiotensin II, aldosterone and cortisol were similar in drinkers and nondrinkers. To investigate differences that may arise when sympathoadrenal activity was stimulated, the subjects underwent a series of standardized physiologic stresses: isometric hand grip, mental arithmetic, cold pressor testing, standing and bicycle exercise. Blood pressure and heart rate responses were similar in drinkers and nondrinkers, although the differences in blood pressure between the two groups tended to become smaller after certain stresses. No differences in the plasma levels of free or conjugated catecholamines were apparent after these stresses. Plasma renin activity increased only after bicycle exercise, and this was similar in both groups. Plasma cortisol levels did not increase. The higher blood pressure in drinkers, therefore, cannot be explained by increased activity of the sympathoadrenal and renal pressor mechanisms.

Effects of Alcohol Consumption on Serum Lipoprotein-Lipid and Apolipoprotein Concentrations Results from an Intervention Study in Healthy Subjects

Serum levels of cholesterol, triglyceride, cholesterol in low density lipoprotein (LDL) and in high density lipoprotein (HDL) and its major subfractions, and of apolipoproteins A-I, A-II and B were measured in 48 healthy men at the end of two 6-week periods in which they consumed normal alcohol (5.0%, v/v) or low alcohol (0.9%, v/v) beer, respectively. Other dietary and behavioural variables were kept constant. Mean levels of triglyceride, HDL cholesterol, HDL2- and HDL3 cholesterol, and apolipoproteins A-I and A-II were higher at the end of the normal compared with the low alcohol periods, and levels of LDL cholesterol were lower. Body weight was greater at the end of the normal alcohol period than at the end of the period of low alcohol but multiple regression analysis suggested that the changes in lipoprotein-lipid and apolipoprotein levels were due primarily to the change in alcohol consumption rather than concomitant changes in body weight. This study confirms an effect of alcohol on both major subfractions of HDL and on its major apolipoproteins.

Two-way factorial study of alcohol and salt restriction in treated hypertensive men.

The aim of this study was to determine whether moderate restriction of dietary salt intake leads to an additional fall in blood pressure in treated hypertensive men who are asked to simultaneously reduce their usual alcohol intake. Sixty-three subjects entered an initial 2-week familiarization period during which they continued their usual alcohol intake and commenced a low sodium diet (less than 60 mmol/day) supplemented with 100 mmol sodium chloride per day as enteric-coated tablets. Subjects were then randomly assigned to either drink a low alcohol beer alone for a 4-week period (reducing their self-reported alcohol consumption from 537 to 57 ml/week) or to continue their usual alcohol intake (543 versus 557 ml/week). Within the low and normal alcohol intake groups, subjects were assigned to either a low or normal sodium intake. The low sodium groups continued the sodium-restricted diet but were switched to placebo sodium chloride tablets for the 4 weeks. This resulted in a fall in the 24-hour urinary sodium excretion from 144 to 69 mmol/day. The normal sodium groups continued the low sodium diet but kept taking 100 mmol/day of the sodium chloride tablets, and their urinary sodium excretion remained unchanged (125 versus 142 mmol/day). Regular antihypertensive therapy was continued throughout. Fifty-nine subjects completed the trial. In those who reduced their alcohol intake there was a fall in both systolic blood pressure (-5.4 mm Hg supine, p less than 0.01) and diastolic blood pressure (-3.2 mm Hg supine, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of eating bananas on plasma free and sulfate-conjugated catecholamines

Abstract The effect of eating bananas, a known and rich source of biogenic amines, on plasma free and sulfate-conjugated catecholamines was examined in normal human volunteers. Before ingestion conjugated norepinephrine (NE) and epinephrine (E) comprised 60% and 84% of the total concentration respectively. Free dopamine (DA) was undetectable. Although there was no change in free NE and E levels after eating bananas, free DA became measurable in some subjects. In contrast, conjugated NE and particularly DA, increased markedly in all subjects. More detailed study in 2 subjects indicated that this increase may persist for 8 hours after consumption. Available evidence suggests that sulfate conjugation of free catecholamines in banana largely takes place in the gut. It is important therefore to consider dietary influences when the physiological role of conjugated catecholamines. and perhaps free dopamine, is being assessed.

Determinants of blood pressure in childhood and adolescence

Relationships between blood pressure and dietary factors were investigated in 434 boys and 450 girls aged 9 years. Dietary data were obtained from a food-frequency questionnaire which was completed by parents. This was used to estimate daily energy intake and the intake of 14 nutrients considered likely to influence blood pressure. Blood pressure was tested for relationships to absolute and calorie-adjusted intakes of each nutrient after adjustment for age, weight, height, socio-economic status and the month of examination. Ambient temperature was the most important determinant of blood pressure, an increase of 10°C being associated with a 6-7mmHg fall in blood pressure. Diastolic blood pressure in boys was negatively related to energy intake and to calorie-adjusted fibre intake. Mean adjusted diastolic blood pressure in boys in the top fibre intake quartile was 2.5mmHg lower than that in the lowest quartile. Systolic blood pressure in girls was negatively related to calorie-adjusted intakes of protein. There were no relationships between blood pressure and calorie-adjusted intakes of fats, carbohydrates, sodium, potassium, calcium or magnesium