Acute effects of coffee on QT interval in healthy subjects

The coronary endothelial function is recognized to have an important role in the physiology of the diastolic ventricular relaxation, a phase of the heart cycle that influences the electrocardiographic QT interval. Endothelial function is investigated in vivo by flow mediated dilation (FMD) in the brachial artery and has proven to be a strong predictor of both coronary endothelial function and cardiovascular events. It has been reported that coffee acutely induces FMD changes. In particular, the brachial artery FMD seems to decrease after caffeinated coffee (CC) and to increase after decaffeinated coffee (DC) ingestion. Since the cardiovascular effects of coffee are still a debated matter, this study aimed at investigating with a randomized, double-blind crossover design, if the QT interval of adult healthy subjects (19 males and 21 females) changes in the hour following CC or DC ingestion. Both systolic and diastolic blood pressure were higher in the hour following the ingestion of CC; the heart rate significantly increased 30 minutes after CC ingestion. A significant increase of the QT duration was observed one hour after DC ingestion (398.9 ± 3.8 vs 405.3 ± 3.7 msec; P < 0.05), not after CC. The QT interval corrected for heart rate did not significantly change following CC or DC ingestion. In conclusion, despite CC and DC previously demonstrated to influence the FMD they do not seem to induce a significant unfavourable acute change of the left ventricular repolarization. Further investigations are required to elucidate the effects of coffee in subjects with cardiovascular diseases

Short and middle term effects of hypocaloric low carbohydrate diet vs hypocaloric Mediterranean diet on endothelial function in obese subjects

Adequate nutritional treatment is required to address the problem of increasing prevalence of obesity in Western countries. The Mediterranean diet style is now acknowledged to have large scientific evidences in terms of cardiovascular prevention. However, many popular diets are diffusing also as self-prescribed treatments. Among those, the efficacy of low-carbohydrate diets (also known as Atkins’ diet in its most popular variety) has been addressed by some investigations. It is generally concluded that the low-carbohydrate diet is able to induce a greater weight loss, at least in the middle term, and a better serum lipid profile than the conventional diet. In this longitudinal, randomised, open study we compared the effects on endothelial function of a hypocaloric low-carbohydrate diet (according to the Atkins’ diet; AD) versus a similarly hypocaloric Mediterranean diet (MD). Overweight-obese (range of BMI: 27-34.9 Kg/m2; range of age: 30-50 years) otherwise healthy, normal glucose tolerant women were enrolled and randomly assigned to one of the two dietary treatments until reaching the final number of 10 women for each group of treatment. So, twenty-five women were enrolled and five of them (3 in the MD group and 2 in the AD group) were subsequently excluded from the study due to intercurrent diseases (1 subject) or declaration of inadequate compliance (2 subjects) or f voluntary drop out (2 subjects). Measurements were performed before (T0), 5-7 days (T5) and 2 months (T60) after starting the diet treatment. Endothelial function was investigated at each time of the study by measuring the brachial artery flow-mediated dilation (FMD). Serum concentrations of insulin, adiponectin, interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and 8-iso-prostaglandin (8-iso-PG) F2α were also assessed at each time of the study. Urinary ketone bodies were observed at T5 only in AD group. Briefly, body weight was not significantly decreased at T5 in both groups; as expected, a higher body weight reduction was observed at T60 in AD group (change in body weight T60 – T0, mean ± sem, MD -4.9 ± 0.6 Kg vs AD -7.6 ± 0.8 Kg, p= 0.014). The FMD was significantly reduced at T5 in the AD group and increased at T60 until reaching the T0 values (T0: 12.2 ± 2.9; T5: 5.2 ± 0.8; T60: 11.0 ± 1.2 %; p< 0.05 T5 vs T0 and T60). On the contrary, the FMD increased significantly at T5 in the MD group and decreased until reaching values comparable to those of T0 at T60 (T0: 10.3 ± 2.3; T5: 14.5 ± 2.8; T60: 10.6 ± 1.9 %; p< 0.05 T5 vs T0 and T60). This trend of FMD change was observed in each subject. Insulin concentrations and HOMA-I decreased significantly at T5 and at T60 in both groups. Adiponectin and TNF-α concentrations remained unchanged in both groups throughout the study. Both IL-6 and 8-iso-PGF2α increased significantly at T5 in the AD group and decreased at T60 to values comparable to T0 (IL-6: T0 57.5 ± 9.0, T5 78.1 ± 10.9, T60 56.6 ± 6.8 pg/ml; T5 vs T0 p< 0,005, T5 vs T60 p< 0,02; 8-iso-PGF2α: T0 171.5 ± 30.6, T5 222.6 ± 35.1, T60 178.7 ± 25.8 pg/ml; T5 vs T0 p< 0,005, T5 vs T60 p< 0,02); no significant change was observed in the MD group. This study suggests that the hypocaloric low-carbohydrate diet induces a significant endothelial dysfunction in the short term (5-7 days) that is reverted in the middle term (2 months) as suggested by both the brachial artery FMD and serum markers of inflammation (IL-6) and oxidative stress (8-iso-PGF2α). On the contrary, the hypocaloric Mediterranean diet is able to improve the endothelial function at least in the short term. These effects are independent of body weight loss. Therefore, this study points out also the potential disadvantages of low-carbohydrate diets when prescribed (or self-prescribed) especially in subjects at high cardiovascular risk

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.: 0min, 7.7±0.6; 30min, 6.3±0.7; 60 min, 6.0±0.8%; ANOVA (analysis of variance), Po0.05), but it did not significantly increase after DC ingestion (0min, 6.9±0.6; 30min, 8.1±0.9; 60min, 8.5±0.9%; P1⁄40.115). 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 (0min, 15.8±0.9; 60min, 15.0±0.8mU/ml; Po0.05) and C-peptide (0min, 1.25±0.09; 60 min, 1.18±0.09 ng/ml; Po0.01) 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

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

Background Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of dif- ferent 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-a] and a marker of oxidative stress [8-iso-prostaglandin F2a (8-iso-PGF2a)] 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 · time interaction). Serum concentrations of IL-6 and 8-iso-PGF2a 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

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 two groups based on the presence (MS+: n= 50) or absence (MS-: n= 40) of metabolic syndrome. The study design was cross-sectional. The three-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, BMI (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 size was higher in the MS- group (163 +/- 8 kJ/Kg-FFM.24h) than in the MS+ group (138 +/- 4 kJ/Kg-FFM.24h; p <0.03). The DRT test results were similar in both groups except that the 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 metabolic syndrome have an energy sparing metabolism