Comparative effects of three popular diets on lipids, endothelial function, and C-reactive protein during weight maintenance.

Although popular diets focus on weight loss and their favorable biochemical and physiological effects, fewer investigations have evaluated the biological impact of these diets during weight maintenance. To study this issue, three popular diets-Atkins, South Beach, and Ornish-were tested in a randomized and counterbalanced crossover study between January and December 2006. Participants completed each of the three 4-week isocaloric dietary intervention phases followed by a 4-week washout period. They were weighed weekly and caloric adjustments made if weight change exceeded 1 kg. At the completion of each dietary phase, 3-day food records were analyzed, fasting blood sampled, and brachial artery reactivity testing performed. Eighteen adults completed all three isocaloric dietary phases. During the South Beach and Ornish maintenance phase, there were significant reductions in low-density lipoprotein cholesterol (11.8%; P=0.01, 16.6%; P=0.0006, respectively) compared to prediet baseline. In addition, in contrast to the Atkins maintenance phase, significant reductions in low-density lipoprotein cholesterol and apolipoprotein B levels were observed after the South Beach (P=0.003, P=0.05; repeated measures analyses of variance) and Ornish maintenance phases (P=0.0004, P=0.006, repeated measures analyses of variance). Brachial artery testing revealed an inverse correlation between flow-mediated vasodilatation and intake of saturated fat (r=-0.33; P=0.016). These data suggest that during weight maintenance, less favorable biological effects are observed during a simulated, high-fat Atkins diet when compared to the South Beach and Ornish diet. The findings support additional study in subjects with visceral obesity and the metabolic syndrome, in whom an increased risk of coronary disease at baseline may be accentuated with chronic consumption of a diet that exhibits unfavorable effects on lipids and endothelial function.

The genetic response to short-term interventions affecting cardiovascular function: rationale and design of the Heredity and Phenotype Intervention (HAPI) Heart Study.

BACKGROUND: The etiology of cardiovascular disease (CVD) is multifactorial. Efforts to identify genes influencing CVD risk have met with limited success to date, likely because of the small effect sizes of common CVD risk alleles and the presence of gene by gene and gene by environment interactions. METHODS: The HAPI Heart Study was initiated in 2002 to measure the cardiovascular response to 4 short-term interventions affecting cardiovascular risk factors and to identify the genetic and environmental determinants of these responses. The measurements included blood pressure responses to the cold pressor stress test and to a high salt diet, triglyceride excursion in response to a high-fat challenge, and response in platelet aggregation to aspirin therapy. RESULTS: The interventions were carried out in 868 relatively healthy Amish adults from large families. The heritabilities of selected response traits for each intervention ranged from 8% to 38%, suggesting that some of the variation associated with response to each intervention can be attributed to the additive effects of genes. CONCLUSIONS: Identifying these response genes may identify new mechanisms influencing CVD and may lead to individualized preventive strategies and improved early detection of high-risk individuals.

Coronary artery calcification in patients with primary hyperparathyroidism in comparison with control subjects from the multi-ethnic study of atherosclerosis.

OBJECTIVE: To determine whether coronary artery calcification (CAC) is increased in patients with primary hyperparathyroidism (pHPT) because of the presence of hypercalcemia, which has been shown in vitro to promote vascular calcification. METHODS: Electron beam computed tomography of the coronary arteries was performed on 20 patients with pHPT referred to our endocrinology clinic for evaluation of hypercalcemia. All patients were nonsmokers, with normal renal function, no history of diabetes, and no history of coronary artery disease. CAC in the patients with pHPT was compared with that in population-based control subjects from the Multi-Ethnic Study of Atherosclerosis (MESA). Two methods of analysis were used: (1) calculation of the odds ratio of CAC and (2) a nested case-control (1:4) study. RESULTS: One patient with pHPT had a history of nephrolithiasis; the other 19 patients were asymptomatic. The mean age (+/- SD) of the patients with pHPT was 57.3 +/- 9.1 years, the mean serum calcium concentration was 2.68 +/- 0.18 mmol/L, and the mean intact parathyroid hormone level was 119 +/- 76.5 pg/mL. Of the 20 patients, 14 had CAC scores of zero. The odds ratio for measurable CAC in the presence of pHPT in comparison with that in the MESA control subjects was 0.17, which was not significant. In the matched analysis, the CAC scores for the patients with pHPT did not differ significantly from those for the MESA control subjects (P = 0.25 with use of the Wilcoxon test). CONCLUSION: We found no evidence for a difference in CAC in patients with pHPT in comparison with the population-based control subjects in this small pilot study.

Exercise-induced hypertension, endothelial dysfunction, and coronary artery disease in a marathon runner.

Aerobic activity performed on a regular basis is 1 of several lifestyle recommendations endorsed to reduce risk of coronary disease. However, 1 potential concern of arduous aerobic activity is exercise-induced hypertension. This is the first case to our knowledge, of accelerated coronary calcification in an otherwise asymptomatic middle-aged male marathon runner devoid of traditional cardiovascular risk factors. As a consequence of exercise-induced hypertension and associated oxidative stress, improvement of endothelial dysfunction occurred after antioxidant supplementation. In conclusion, vigorous aerobic activity in susceptible individuals may promote oxidative stress and coronary atherosclerosis.

A randomized, double-blind trial comparing the effects of amlodipine besylate/benazepril HCl vs amlodipine on endothelial function and blood pressure.

Evidence suggests that renin-angiotensin-aldosterone system inhibition ameliorates endothelial dysfunction. The authors examined the effect of amlodipine besylate/benazepril HCl combination treatment compared with amlodipine besylate monotherapy in modulating endothelial dysfunction. This multicenter, double-blind, 12-week study randomized 70 hypertensive subjects with at least one other endothelial dysfunction risk factor to amlodipine besylate/benazepril HCl (5/20 mg/d force-titrated to 5/40 mg/d) or amlodipine besylate monotherapy (5 mg/d force-titrated to 10 mg/d). Both the combination and monotherapy produced significant median increases from baseline in percentage flow-mediated vasodilation (2.0% and 1.2%, respectively) and percentage change in percent flow-mediated vasodilation (25% and 16%, respectively). These improvements were numerically larger with combination treatment, but between-group differences did not achieve statistical significance. Reductions in systolic and diastolic blood pressure were significantly greater (P=.0452/P=.0297) with combination treatment (-18.6/-12.3 mm Hg) than with monotherapy (-14.8/-9.1 mm Hg). A highly positive correlation between change in systolic blood pressure and change in percent of flow-mediated vasodilation was demonstrated only for combination treatment.