R. Vandongen

REGULAR ALCOHOL USE RAISES BLOOD PRESSURE IN TREATED HYPERTENSIVE SUBJECTS: A Randomised Controlled Trial

44 men with treated essential hypertension who were moderate to heavy drinkers took part in a randomised, controlled, crossover trial of the effects of alcohol intake on blood pressure. Usual antihypertensive treatment was maintained throughout 6 weeks of normal drinking and 6 weeks of drinking only a low-alcohol beer. Self-reported changes in alcohol consumption (mean [SEM] from 452 [30] ml ethanol/week during normal drinking to 64 [8] ml/week while drinking the low-alcohol beer) were confirmed by biochemical measurements. Mean systolic and diastolic blood pressures were significantly lower during the last 2 weeks of the low-alcohol period than during the normal-alcohol period, the mean difference in the supine readings being 5.0 (1.4) and 3.0 (0.9) mm Hg, respectively. Regression analysis suggested that reduction in alcohol intake contributed to the fall in both systolic and diastolic blood pressures independently of changes in weight. Thus, curtailing alcohol intake may lead to improved blood-pressure control and may reduce the need for antihypertensive drugs.

BLOOD-PRESSURE-LOWERING EFFECT OF A VEGETARIAN DIET: CONTROLLED TRIAL IN NORMOTENSIVE SUBJECTS

59 healthy, omnivorous subjects aged 25-63 years were randomly allocated to a control group, which ate an omnivorous diet for 14 weeks, or to one of two experimental groups, whose members ate an omnivorous diet for the first 2 weeks and a lacto-ovo-vegetarian diet for one of two 6-week experimental periods. Mean systolic and diastolic blood pressures did not change in the control group but fell significantly in both experimental groups during the vegetarian diet and rose significantly in the experimental group which reverted to the omnivorous diet. Adjustment of the blood-pressure changes for age, obesity, heart rate, weight change, and blood pressure before dietary change indicated a diet-related fall of some 5-6 mm Hg systolic and 2-3 mm Hg diastolic. Although the nutrient(s) causing these blood-pressure changes are unknown, the effects were apparently not mediated by changes in sodium or potassium intake.

Leukocyte and platelet function and eicosanoid production in subjects with hypercholesterolaemia

A group of 22 subjects with type IIA hypercholesterolaemia (mean serum cholesterol = 8.3 +/- 0.3 mmol/l) were sex, age and weight matched with 22 control subjects (mean serum cholesterol = 4.5 +/- 0.1 mmol/l). Diastolic blood pressure was significantly higher in hypercholesterolaemic subjects (79.2 +/- 1.4 mm Hg) than in control subjects (71.9 +/- 1.4 mm Hg). While the high cholesterol group had 52% greater thromboxane production in clotted whole blood than controls this difference was not significant, and the platelet aggregation and serotonin secretion response to doses of collagen, ADP and arachidonic acid were similar between the 2 groups. Polymorphonuclear leukocyte (PMN) chemiluminescence (used as a measure of reactive oxygen species production) in response to low doses of the chemotactic-peptide FMLP and opsonized zymosan was significantly greater in high cholesterol subjects compared to their matched controls. The production of platelet activating factor (PAF) by calcium ionophore (2.5 micrograms) stimulated PMN isolated from hypercholesterolaemic subjects (11.5 +/- 1.4 ng/10(6) cells) was significantly greater than PAF production by cells from the control group (8.3 +/- 1.0 ng/10(6) cells). Leukotriene B4 release by PMN in response to calcium ionophore did not differ between the 2 groups. These data suggest a degree of leukocyte activation in hypercholesterolaemic subjects compared to controls with normal cholesterol. In addition, plasma levels of lyso-PAF were higher in high cholesterol subjects (317 +/- 21 ng/ml) compared to their matched controls (271 +/- 18 ng/ml) perhaps indicating increased plasma acetylhydrolase activity in subjects with raised cholesterol levels. Recently described biological activity for lyso PAF suggests a possible role for this substance in atherogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

New findings in the fatty acid composition of individual platelet phospholipids in man after dietary fish oil supplementation

Nine healthy male volunteers were given 15 Max EPA fish oil capsules providing 2.67 g of eicosapentaenoic acid (EPA, 20∶5ω3) and 1.72 g of docosahexaenoic acid (DHA, 22∶6ω3) daily for 3 wk. Measurements were taken at baseline, at the end of the fish-oil period, and at 2 and 6 wk postsupplementation. The effect of fish oil on plasma lipids and the fatty acid composition of individual platelet phospholipids was studied. In general, the proportions of 20∶5ω3 and 22∶6ω3 in platelet phosphoglycerides were substantially increased mainly at the expense of arachidonic acid (AA, 20∶4ω6). A large and significant increase in the relative EPA content of phosphatidylcholine (PC) (P<0.001) and phosphatidylethanolamine (PE) (P<0.001) was noted at the end of the 3 wk supplementation. We have also shown for the first time a small but significant (P<0.001) incorporation of EPA in phosphatidylserine (PS). Incorporation of DHA was also detected in PC, PE and PS, whereas the relative AA content of these phospholipids was significantly reduced. Fish oil supplementation led to a significant increase of 22∶5ω3 in PS and decreases of 20∶3ω6 in PC and 22∶4ω6 in PE. Postsupplementation measurements showed a gradual return of all fatty acids to baseline levels. The fatty acid composition of the phosphatidylinositol (PI) fraction remained unchanged throughout the trial period. We conclude that in humans ω3 fatty acids are incorporated into platelet membrane phospholipid subclasses with a high degree of specificity.

Vegetarian diet and blood pressure levels: incidental or causal association?

Evidence that nutrients other than the major cations may influence blood pressure levels stems from studies of acculturated vegetarians and from randomized controlled dietary trials. Earlier studies of vegetarians focused on religious groups and on vegans, making it difficult to know whether their lower blood pressures were due to diet per se or to other aspects of lifestyle. Seventh-day Adventist vegetarians showed significantly less hypertension and lower blood pressures compared with Mormon omnivores, effects which were independent of differences in obesity and not due to altered sodium intake. Subsequently, controlled dietary intervention studies in healthy normotensive omnivores provided more direct evidence for a blood pressure-lowering effect of a lactoovovegetarian diet with reversible changes of 5-6 mm Hg systolic and 2-3 mm Hg diastolic occurring over 6-wk periods. Similar dietary effects in mild hypertensive subjects provides impetus for identifying the responsible nutrients.

Effects on blood pressure of omega 3 fats in subjects at increased risk of cardiovascular disease.

This study was conducted to compare the effects of omega 3 fatty acids, taken as fish or fish-oil supplements in the setting of a high- or low-fat dietary background, on blood pressure and heart rate in men with moderate cardiovascular risks. One hundred twenty men were randomly allocated to five high-fat (40% of daily energy) and two low-fat (30% of energy) groups to undertaken a 12-week dietary intervention period involving fish, fish oil, or a combination of these. Sodium intake was restricted to less than 90 mmol/d. The five high-fat groups were assigned to take either 6 or 12 fish-oil capsules daily, fish or a combination of fish oil and fish, or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals were devised to provide 1.3 g of eicosapentaenoic acid daily, equivalent to that contained in 6 fish-oil capsules. Subjects were instructed to eat a selection of fish that provided an average of 3.65 g/d (range, 3.2 to 4.1 g/d) of total omega 3 fatty acids. Subjects were seen at regular intervals during the baseline and dietary intervention periods for measurement of weight, blood pressure, heart rate, dietary compliance, urinary electrolyte excretion, platelet phospholipid fatty acids, blood glucose, and insulin concentration. There was a greater fall in both systolic and diastolic blood pressures in subjects allocated fish or fish oil, particularly in the low-fat groups, compared with control subjects. However, there was no significant group effect.(ABSTRACT TRUNCATED AT 250 WORDS)

HAEMODYNAMIC AND NEUROENDOCRINE CONSEQUENCES OF STOPPING SMOKING-A CONTROLLED STUDY

1. The haemodynamic and neuroendocrine consequences of stopping smoking for a 6 week period were studied in thirty‐three smokers and their matched controls.

Clustering of Cardiovascular Risk Factors in Australian Adolescents: Association with Dietary Excesses and Deficiencies

Background: Effective cardiovascular disease prevention requires strategies aimed at those children and adolescents most at risk. This study was designed to identify adolescents with clustering of higher levels of cardiovascular risk factors related to diet, blood pressure, fitness, fatness and blood cholesterol. Methods: A representative sample of 555 schoolchildren aged 15 years from the Perth, Australia metropolitan area, was included in a cross-sectional survey analysing relationships between nutrient intake, fitness, physical activity, percentage of body fat, blood pressure and heart rate. Results: Cluster analysis identified 21.1% of boys and 20.7% of girls with significantly worse risk profiles. Higher cardiovascular risk was associated with both dietary excesses, particularly in fat, cholesterol and sodium intake, and deficiencies of a number of minerals, vitamins and dietary fibre. Socioeconomic status was inversely associated with cardiovascular risk and undernutrition in girls. Conclusions: The analysis has identified a subgroup of about 21% of 15-year-old schoolchildren who share features of a range of unhealthy lifestyle variables, putting them at substantial risk of cardiovascular disease and other ill health in later life.

Controlled comparison of effects of exercise and alcohol on blood pressure and serum high density lipoprotein cholesterol in sedentary males.

1. Seventy‐two sedentary male drinkers, aged 20–45 years, and with mean blood pressure (BP) at entry of 132±1.2/73±0.9 mmHg, completed a 4 week study during which they were assigned randomly to either drink a low alcohol beer (effectively reducing their weekly alcohol intake from 481±47 mL to 52±5 mL) or to continue their normal drinking habits.

WHOLE BLOOD PLATELET AGGREGATION IS NOT AFFECTED BY CIGARETTE SMOKING BUT IS SEX‐RELATED

1. In normal subjects, 18–49 years old, the effects of the smoking habit (>10 cigarettes/day) and the act of smoking two cigarettes over 10 min were studied on whole blood platelet aggregation (in vitro impedance method).