Potatoes, glycemic index, and weight loss in free-living individuals: practical implications.

BACKGROUND: The role of glycemic index (GI) and foods with negative attributes related to GI as part of a weight loss regimen has not been thoroughly assessed in free-living individuals. This study examined the effects of a dietary prescription for energy intake modification, GI, and potato consumption on weight loss, dietary prescription adherence, body composition, and glucose control in a free-living, self-selecting overweight population. METHODS: Ninety overweight (body mass index [BMI] 29.6 ± 3.9) men and women were randomly assigned to one of 3 groups for 12 weeks. Two groups were counseled to reduce their energy intake by 500 kcal/day and consume diets that were predominantly composed of either low- or high-GI foods (low glycemic index energy reduced [LGI-ER] or high glycemic index energy reduced [HGI-ER] diet, respectively). The third group received no energy restriction, GI provision, or nutritional counseling. All groups were instructed to consume 5-7 servings of potatoes per week. Changes in weight, body composition, glucose tolerance, and triglycerides were determined at baseline and 12 weeks. RESULTS: There were no significant differences in weight loss or changes in body composition between the groups; however, modest weight loss and body composition changes were seen from week 0 to week 12 for all groups (p < 0.05). Difficulty achieving the prescribed GI diets was evident in this free-living setting. There were no significant changes within or among treatments for fasting concentrations of triglycerides, glucose tolerance, insulin, or insulin sensitivity. CONCLUSIONS: The results indicate that in a free-living population of men and women, weight loss is associated with energy intake reduction. Potato intake did not cause weight gain and following either a high- or low-GI dietary prescription was difficult for free-living subjects, emphasizing the complex nature of changing dietary patterns.

Exercise and heart failure in the elderly.

In this review, we will examine the physiological responses to exercise in elderly populations (age > 65 years) with and without evidence of heart failure. Aging per se in both men and women is associated with a ~40% lower maximum oxygen consumption in sedentary subjects. In trained individuals, this value is 25-32% lower. A smaller SV accounts for nearly 50% of these age-related differences, and the remainder is explained by a lower maximal HR and reduced oxygen extraction. Exercise training is also associated with an increase in the arteriovenous O(2) difference in previously sedentary elderly men and women, which probably contributes to the overall beneficial effect of training in the elderly. However, during vigorous exercise (125 W), the cardiac output in the elderly is dependent upon an age-related increase in end-diastolic volume and stroke volume, which "compensates" partially for the age-related decrease in heart rate. Hence, in elderly individuals, the stroke volume during exercise depends upon diastolic filling. The changes that occur in the heart are also associated with an overall reduction in efferent sympathetic nerve activity. Despite this decline, the metaboreflex initiated by receptors in exercising muscles remains the main determinant of sympathetic activation (to maintain blood pressure) during exercise in the elderly. It is recognized that aging is associated with the development of heart failure, particularly in women in whom its prevalence increases >twofold from age 65-69 (6.6%) to age 85 years (14%). Almost half the people presenting with heart failure appear to have normal left ventricular systolic function, a phenomenon that is more common in women. Exercise training in elderly people with and without heart failure appears to have a beneficial effect in terms of enhancing the quality of life and functional capacity. Mortality benefit in the latter has not been established with certainty.

Aspirin for primary prevention of myocardial infarction: what is the evidence?

BACKGROUND: Aspirin has been advocated as a primary prevention measure for myocardial infarction (MI) for more than 2 decades. While several meta-analyses have supported this view, others have differed. All these analyses have focused on data from 6 major clinical trials. METHODS: We have provided a detailed analysis of the methods used in the individual trials (n = 6) included in the published meta-analyses. RESULTS: The major limitations of the meta-analyses relate to inclusion of heterogeneous trials characterized by widely differing study cohorts, absence of true control groups, lack of identification of silent MIs, failure to specify type of stroke, and inadequate information on management of conventional cardiac risk factors such as hypertension and hyperlipidemia. These issues preclude meaningful conclusions on the effects of aspirin in primary prevention of MI. CONCLUSIONS: This analysis does not support a general recommendation for the use of aspirin for primary prevention of MI and also suggests that effective management of risk factors in accordance with current guidelines may attenuate any potential benefit from aspirin with respect to MI. However, there may be a modest benefit in postmenopausal women with respect to stroke.

Attenuation of meal-induced inflammatory and thrombotic responses in overweight men and women after 6-week daily strawberry (Fragaria) intake. A randomized placebo-controlled trial.

AIM: A pro-thrombotic, pro-inflammatory diet can play a causative role in atherosclerotic-cardiovascular diseases. Dietary intervention studies provide insight into their pathophysiological manifestations and opportunities for prevention and management. We previously showed in an acute-meal setting that a beverage containing polyphenolic- and antioxidant-rich strawberry (Fragaria) vs placebo attenuated postprandial (fed-state) increases in biomarkers of oxidative and inflammatory stress, and insulin concentrations, induced by a high carbohydrate/fat (HCF) meal. In the present study, we aimed to extend our findings and investigate hypotheses related to the effects of chronic/6-week (wk) strawberry consumption on HCF meal-induced increases in glucose, insulin, and indicators of inflammation and hemostasis. METHODS: In a crossover design, 14 women and 10 men (mean age, BMI: 50.9±15 years, 29.2±2.3 kg/m(2), respectively), were randomized to a 6-wk strawberry or placebo beverage followed by an HCF meal with assessments for 6-hours (h) postprandially. RESULTS: HCF meal responses after 6-wk strawberry beverage showed significantly attenuated postprandial PAI-1 concentrations compared to the placebo (p =0.002); the difference was most notable at 6 h. The IL-1 ß response was attenuated with strawberry compared to the placebo (p =0.05). IL-6 attenuation was apparent but non-significant; IL-6 rose significantly from baseline to 6 h after the HCF meal following a placebo (p ≤0.01), although it remained relatively flat following the strawberry beverage from fasting to 6 h. No significant treatment-related differences were apparent for platelet aggregation, hsCRP, TNF-α, insulin, or glucose. CONCLUSION: These data are the first to suggest that regular consumption of strawberry, a polyphenolic- and antioxidant-rich fruit, may provide protection from HCF meal-induced increases in fibrinolytic and inflammatory factors in at-risk men and women.

Strawberry modulates LDL oxidation and postprandial lipemia in response to high-fat meal in overweight hyperlipidemic men and women.

BACKGROUND: Elevated levels of lipids, such as total cholesterol (TC), low-density lipoprotein cholesterol (LDL), and triglycerides (TG), are widely recognized as risk factors for cardiovascular disease (CVD). Oxidized LDL (OxLDL) is an emerging risk factor considered relevant in oxidative stress and endothelial dysfunction, which is implicated in the progression of CVD. Consumption of a diet rich in polyphenols may be cardioprotective through its impact on oxidative stress and protecting LDL from oxidation. OBJECTIVES: This study was designed to test the ability of strawberry phenolic compounds to mitigate the postprandial effects of a high-fat meal on OxLDL as well as investigate the effects of phenolic compounds on lipid metabolism. METHODS: Twenty-four hyperlipidemic men and women (14 women, 10 men; mean age 50.9 +/- SD 15 years) were recruited to participate in this randomized, single-blind, placebo-controlled, 12-wk crossover trial. After a 10-day run-in period, subjects consumed either an active strawberry beverage (Str; containing 10 g freeze-dried fruit) or a placebo (Pbo) beverage matched in energy and macronutrient composition for 6 weeks. Twice before randomization and once at the 6-week crossover point, subjects received either Str or Pbo with a high-fat challenge meal (HFM). TC, LDL, high-density lipoprotein cholesterol, TG, and OxLDL were measured at defined intervals for 6 h before and after HFM challenge. Fasting concentrations of blood variables at 0, 6, and 12 weeks were compared to assess chronic intake of Str or Pbo. RESULTS: After the HFM during the run-in period, TG and OxLDL were lower after Str than Pbo (p = 0.005, p = 0.01, and p = 0.0008, respectively). HFM responses after 6 weeks of Str versus Pbo resulted in decreased lipid levels and a sex by treatment interaction for OxLDL (p = < 0.0001, and p = 0.0002). CONCLUSION: The present results support a role for strawberry in mitigating fed-state oxidative stressors that may contribute to atherogenesis.

Effect of grape seed extract on blood pressure in subjects with the metabolic syndrome.

This study was undertaken to determine whether grape seed extracts (GSE) that contain powerful vasodilator phenolic compounds lower blood pressure in subjects with the metabolic syndrome. The subjects were randomized into 3 groups-(a) placebo, (b) 150 mg GSE per day, and (c) 300 mg GSE per day-and treated for 4 weeks. Serum lipids and blood glucose were measured at the beginning of the study and at the end. Blood pressure was recorded using an ambulatory monitoring device at the start of the treatment period and at the end. Both the systolic and diastolic blood pressures were lowered after treatment with GSE as compared with placebo. There were no significant changes in serum lipids or blood glucose values. These findings suggest that GSE could be used as a nutraceutical in a lifestyle modification program for patients with the metabolic syndrome.

Rapidly adapting receptors in acute heart failure and their impact on dyspnea.

Acute heart failure is associated with dyspnea that is usually defined as difficulty in breathing that is accompanied by an element of distress. It is commonly associated with an increase in the rate of ventilation, wheezing, an increase in airway secretions and cough. This review examines the reflexes which generate these responses with particular reference to the role of rapidly adapting receptors (RAR) in the airways. The essential feature of acute heart failure is an increase in pulmonary extravascular fluid volume. Small acute increases in extravascular fluid volume in the airways activate the RAR. With larger increases both the RAR and the C-fiber receptors in the airways and the alveoli are activated. Activation of RAR causes a reflex increase in respiratory rate, tracheal tone and mucus secretion from the airways. It is suggested that the RAR play a significant role in monitoring changes in the extravascular fluid volume of the airways and mediate the respiratory reflexes associated with acute heart failure.

Strawberry extract caused endothelium-dependent relaxation through the activation of PI3 kinase/Akt.

Polyphenolic compounds are vasodilators and help to lower the risk of cardiovascular diseases. We hypothesized that a freeze-dried strawberry powder that is rich in polyphenolic compounds would cause an endothelium-dependent relaxation (EDR) through the activation of phosphatidylinositol-3 (PI3)-kinase/protein kinase B (Akt) in rabbit aorta. The powder was prepared by freeze drying a homogenate of ripe California strawberry fruits. An aqueous extract of strawberry powder was applied to rabbit aortic rings suspended in organ baths containing Krebs-Henseleit buffer maintained at 37 degrees C. In aortic rings precontacted with norepinephrine, the extract produced a dose-dependent relaxation. The maximum relaxations elicited by the extract (73.1 +/- 1.0%) were similar to those elicited by acetylcholine (68.2 +/- 1.5%) ( n = 14 for each). The relaxation by strawberry extract was abolished by removal of the endothelium and by prior incubation with N omega-nitro- l-arginine methyl ester hydrochloride (L-NAME), confirming the essential role of endothelial nitric oxide synthase (eNOS). The responses to the strawberry were also abolished by incubation with wortmannin and LY294002, which are inhibitors of PI3 kinase. Using immunoblotting, we also demonstrated that the strawberry extract induced the phosphorylation of both Akt and eNOS in human umbilical vein endothelial cells (HUVECs) via PI3 kinase/Akt pathway. Taken together, our novel findings suggest that the EDR induced by the strawberry extract was mediated by activation of the PI3 kinase/Akt signaling pathway, resulting in phosphorylation of eNOS.