Acute effects of coffee on endothelial function in healthy subjects.

BACKGROUND/OBJECTIVES: Coffee is the most widely consumed beverage in the world, but its effect on the cardiovascular system has not been fully understood. Coffee contains caffeine and antioxidants, which may influence endothelial function, both of which have not yet been investigated. The objective of this study was to investigate the acute effects of coffee on endothelial function measured by brachial artery flow-mediated dilation (FMD). SUBJECTS/METHODS: A total of 20 (10 males and 10 females) healthy non-obese subjects underwent a double-blind, crossover study. Subjects ingested one cup of caffeinated (CC) and one cup of decaffeinated (DC) Italian espresso coffee in random order at 5- to 7-day intervals. RESULTS: Following CC ingestion, FMD decreased progressively and significantly (mean+/-s.e.m.: 0 min, 7.7+/-0.6; 30 min, 6.3+/-0.7; 60 min, 6.0+/-0.8%; ANOVA (analysis of variance), P<0.05), but it did not significantly increase after DC ingestion (0 min, 6.9+/-0.6; 30 min, 8.1+/-0.9; 60 min, 8.5+/-0.9%; P=0.115). Similarly, CC significantly increased both systolic and diastolic blood pressure; this effect was not observed after DC ingestion. Blood glucose concentrations remained unchanged after ingestion of both CC and DC, but insulin (0 min, 15.8+/-0.9; 60 min, 15.0+/-0.8 muU/ml; P<0.05) and C-peptide (0 min, 1.25+/-0.09; 60 min, 1.18+/-0.09 ng/ml; P<0.01) blood concentrations decreased significantly only after CC ingestion. CONCLUSIONS: CC acutely induced unfavorable cardiovascular effects, especially on endothelial function. In the fasting state, insulin secretion is also likely reduced after CC ingestion. Future studies will determine whether CC has detrimental clinically relevant effects, especially in unhealthy subjects.

Dose-dependent effects of decaffeinated coffee on endothelial function in healthy subjects.

BACKGROUND/OBJECTIVES: Coffee is known to contain antioxidant substances whose effects may be blunted because of caffeine that may unfavorably affect the cardiovascular system. This study was designed to investigate the acute dose-dependent effects of decaffeinated coffee (DC) on endothelial function measured by the brachial artery flow-mediated dilation (FMD). SUBJECTS/METHODS: A total of 15 (8 men and 7 women) healthy nonobese subjects underwent a single-blind, crossover study. Subjects ingested one and two cups of decaffeinated Italian espresso coffee in random order at 5- to 7-day intervals. RESULTS: In the hour following the ingestion of two cups of DC, FMD increased (mean+/-s.e.m.): 0 min, 7.4+/-0.7%; 30 min, 8.0+/-0.6%; 60 min, 10.8+/-0.8%; P<0.001) as compared to consumption of one cup of DC (0 min, 6.9+/-0.7%; 30 min, 8.4+/-1.2%; 60 min, 8.5+/-1.1%; 3 x 2 repeated-measures analysis of variance: P=0.037 for time x treatment effect). Blood pressure did not differ between groups, and basal heart rate was lower in the two-cup group at baseline and 60 min. CONCLUSIONS: The present study demonstrated a significant acute favorable dose-dependent effect of decaffeinated espresso coffee on endothelial function. Further studies are needed to investigate the effects of chronic use of DC especially with respect to caffeinated coffee and in subjects with cardiovascular diseases.

A low reported energy intake is associated with metabolic syndrome.

BACKGROUND AND AIMS: Metabolic syndrome (MS) may be associated with the presence of an energy-sparing metabolism that predisposes to the excess accumulation of body fat. This study examined the relationship between reported energy intake and obesity in individuals with and without MS. METHODS AND RESULTS: Ninety consecutive non-diabetic obese subjects were divided into 2 groups based on the presence (MS+: no.=50) or absence (MS-: no.=40) of MS. The study design was cross-sectional. The 3-day food record method was used to assess the subjects' usual energy intake and the Diet Readiness Test (DRT) was also administered. Compared to the MS- group, the MS+ group had a significantly higher body weight, body mass index (mean+/-SEM: 39.1+/-1.3 vs 31.5+/-0.9, p<0.001) and fat mass. The absolute energy intake of the MS+ group (8629+/-331 kJ/24h) did not differ from that of the MS- group (8571+/-515 kJ/24h; p=ns). The daily energy intake normalized for the fat-free mass (FFM) size was higher in the MS- group (163+/-8 kJ/kg-FFM x 24h) than in the MS+ group (138+/-4 kJ/kg-FFM x 24h; p<0.03). The DRT test results were similar in both groups except that section 6 (exercise patterns and attitudes) score was lower in the MS+ group (10.0+/-0.5) than in the MS- group (11.9+/-0.5; p<0.01). CONCLUSION: The results of this study support the hypothesis that subjects with MS have an energy-sparing metabolism.

Effects of hypocaloric very-low-carbohydrate diet vs. Mediterranean diet on endothelial function in obese women*.

Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known. The effect of diet on endothelial function in two hypocaloric diets, a very-low-carbohydrate diet (A) and a Mediterranean diet (M), was measured by brachial artery flow-mediated dilation (FMD). Design Using a longitudinal, randomized, open study design, subjects were engaged in a 2-month weight loss diet. FMD, inflammatory cytokines [interleukin-6 (IL-6) and tumour necrosis factor-alpha] and a marker of oxidative stress [8-iso-prostaglandin F2alpha (8-iso-PGF2alpha)] were measured in subjects on three occasions: before initiating the diet (T0), after 5-7 days of dieting (T5) and after 2 months of dieting (T60). The very short- and medium-term time points were established to discriminate respectively the effect of the diet itself (T5) from that of weight loss (T60). Twenty overweight/obese but otherwise healthy women (BMI: 27-34.9 kg m(-2); age 30-50 years) completed the study. Results Group A lost more weight (mean +/- SEM; -7.6 +/- 0.8 kg) than group M (-4.9 +/- 0.6 kg, P = 0.014) at T60. The FMD was not significantly different between the two groups at T0 (group A: 12.2 +/- 2.9% vs. group B: 10.3 +/- 2.3%, P = ns). In group A, FMD was significantly reduced at T5 and returned to baseline at T60; in group M, FMD increased at T5 and returned to baseline at T60 (P = 0.007 for diet x time interaction). Serum concentrations of IL-6 and 8-iso-PGF2alpha were not significantly different between the two groups at T0 and increased significantly at T5 only in group A (P < 0.001 and P < 0.005 respectively). Conclusion As endothelial dysfunction is known to be associated with acute cardiovascular events, this study suggests that the cardiovascular risk might be increased in the first days of a very-low-carbohydrate diet.