Apple polyphenol-rich drinks dose-dependently decrease early-phase postprandial glucose concentrations following a high-carbohydrate meal: a randomized controlled trial in healthy adults and in vitro studies

BackgroundPrevious research demonstrated that a high dose of phlorizin-rich apple extract (AE) can markedly inhibit early-phase postprandial glycemia, but efficacy of lower doses of the AE is unclear.ObjectiveTo determine whether lower AE doses reduce early-phase postprandial glycemia in healthy adults and investigate mechanisms.DesignIn a randomized, controlled, double-blinded, cross-over acute trial, drinks containing 1.8 g (HIGH), 1.35 g (MED), 0.9 g (LOW), or 0 g (CON) of a phlorizin-rich AE were consumed before 75 g starch/sucrose meal. Postprandial blood glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide (GIP) and polyphenol metabolites concentrations were measured 0–240 min, acetaminophen concentrations to assess gastric emptying rate, and 24 h urinary glucose excretion. Effects of AE on intestinal glucose transport were investigated in Caco-2/TC7 cells.ResultsAE significantly reduced plasma glucose iAUC 0–30 min at all doses: mean differences (95% CI) relative to CON were −15.6 (−23.3, −7.9), −11.3 (−19.6, −3.0) and −8.99 (−17.3, −0.7) mmol/L per minute for HIGH, MEDIUM and LOW respectively, delayed T_max (HIGH, MEDIUM and LOW 45 min vs. CON 30 min), but did not lower C_max. Similar dose-dependent treatment effects were observed for insulin, C-peptide, and GIP. Gastric emptying rates and urinary glucose excretion did not differ. Serum phloretin, quercetin and epicatechin metabolites were detected postprandially. A HIGH physiological AE dose equivalent decreased total glucose uptake by 48% in Caco-2/TC7 cells.ConclusionsPhlorizin-rich AE, even at a low dose, can slightly delay early-phase glycemia without affecting peak and total glycemic response.     

Drinks containing anthocyanin-rich blackcurrant extract decrease postprandial blood glucose,insulin and incretin concentrations

Blackcurrants are rich in polyphenolic glycosides called anthocyanins, which may inhibit postprandial glycemia. The aim was to determine the dose-dependent effects of blackcurrant extract on postprandial glycemia. Men and postmenopausal women (14 M, 9 W, mean age 46 years, S.D.=14) were enrolled into a randomized, double-blind, crossover trial. Low sugar fruit drinks containing blackcurrant extract providing 150-mg (L-BE), 300-mg (M-BE) and 600-mg (H-BE) total anthocyanins or no blackcurrant extract (CON) were administered immediately before a high-carbohydrate meal. Plasma glucose, insulin and incretins (GIP and GLP-1) were measured 0–120 min, and plasma 8-isoprostane F_2α, together with arterial stiffness by digital volume pulse (DVP) was measured at 0 and 120 min. Early plasma glucose response was significantly reduced following H-BE (n=22), relative to CON, with a mean difference (95% CI) in area over baseline (AOB) 0-30 min of −0.34 mmol/l.h (−0.56, −0.11, P<.005); there were no differences between the intermediate doses and placebo. Plasma insulin concentrations (AOB 0–30 min) were similarly reduced. Plasma GIP concentrations (AOB 0–120 min) were significantly reduced following H-BE, with a mean difference of −46.6 ng/l.h (−66.7, −26.5, P<.0001) compared to CON. Plasma GLP-1 concentrations were reduced following H-BE at 90 min. There were no effects on 8-isoprostane F_2α or vascular function. Consumption of blackcurrant extract in amounts roughly equivalent to 100-g blackcurrants reduced postprandial glycemia, insulinemia and incretin secretion, which suggests that inclusion of blackcurrant polyphenols in foods may provide cardio-metabolic health benefits. This trial was registered at clinicaltrials.gov as NCT01706653.     

Effect of a single bout of resistance exercise on postprandial glucose and insulin response the next day in healthy, strength-trained men

Postprandial blood glucose and insulin levels are both risk factors for developing obesity, type-2 diabetes, and coronary heart diseases. To date, research has shown that a single bout of moderate- to high-intensity aerobic exercise performed 相似文献   

Both GLP-1 and GIP are insulinotropic at basal and postprandial glucose levels and contribute nearly equally to the incretin effect of a meal in healthy subjects

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are both incretin hormones regulating postprandial insulin secretion. Their relative importance in this respect under normal physiological conditions is unclear, however, and the aim of the present investigation was to evaluate this. Eight healthy male volunteers (mean age: 23 (range 20-25) years; mean body mass index: 22.2 (range 19.3-25.4) kg/m2) participated in studies involving stepwise glucose clamping at fasting plasma glucose levels and at 6 and 7 mmol/l. Physiological amounts of either GIP (1.5 pmol/kg/min), GLP-1(7-36)amide (0.33 pmol/kg/min) or saline were infused for three periods of 30 min at each glucose level, with 1 h "washout" between the infusions. On a separate day, a standard meal test (566 kcal) was performed. During the meal test, peak insulin concentrations were observed after 30 min and amounted to 223+/-27 pmol/l. Glucose+saline infusions induced only minor increases in insulin concentrations. GLP-1 and GIP infusions induced significant and similar increases at fasting glucose levels and at 6 mmol/l. At 7 mmol/l, further increases were seen, with GLP-1 effects exceeding those of GIP. Insulin concentrations at the end of the three infusion periods (60, 150 and 240 min) during the GIP clamp amounted to 53+/-5, 79+/-8 and 113+/-15 pmol/l, respectively. Corresponding results were 47+/-7, 95+/-10 and 171+/-21 pmol/l, respectively, during the GLP-1 clamp. C-peptide responses were similar. Total and intact incretin hormone concentrations during the clamp studies were higher compared to the meal test, but within physiological limits. Glucose infusion alone significantly inhibited glucagon secretion, which was further inhibited by GLP-1 but not by GIP infusion. We conclude that during normal physiological plasma glucose levels, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide contribute nearly equally to the incretin effect in humans, because their differences in concentration and potency outweigh each other.     

Simultaneous decrease of plasma obestatin and ghrelin levels after a high-carbohydrate breakfast in healthy women

Ghrelin is a gut peptide produced mainly by stomach, well known to induce appetite stimulatory actions. Obestatin, a recently identified peptide derived from preproghrelin, was initially described to antagonize stimulatory effect of ghrelin on food intake. The postprandial response of obestatin and its relationship with ghrelin in humans remains unknown. We therefore investigated the postprandial response of obestatin and total ghrelin, acyl and desacyl ghrelin and neuropeptide Y (NPY) to a high-carbohydrate breakfast (1 604 kJ) in eight healthy women (age: 24.2+/-0.82 years; BMI 21.6+/-0.61 kg/m(2)). Blood samples were collected before the meal, and 30, 60, 90, 120 and 150 min after the breakfast consumption. Postprandial plasma obestatin concentrations significantly decreased compared with preprandial levels as well as total ghrelin concentrations and reached the lowest values 90 and 120 min after the meal consumption, respectively (p<0.05). Plasma acyl and desacyl ghrelin concentrations decreased after the breakfast and reached lowest values in 30 and 60 min, respectively (p<0.05). Plasma NPY concentrations were lower than preprandial levels 90 and 150 min after consuming breakfast (p<0.05). In conclusion, we demonstrated in healthy young women that plasma obestatin concentrations decrease similarly to ghrelin after a high-carbohydrate breakfast.     

Influence of consumption of a high-protein vs. high-carbohydrate meal on the physiological cortisol and psychological mood response in men and women

Consumption of meals with different macronutrient contents, especially high in carbohydrates, may influence the stress-induced physiological and psychological response. The objective of this study was to investigate effects of consumption of a high-protein vs. high-carbohydrate meal on the physiological cortisol response and psychological mood response. Subjects (n = 38, 19 m/19f, age =25 ± 9 yrs, BMI = 25.0 ± 3.3 kg/m2) came to the university four times, fasted, for either condition: rest-protein, stress-protein, rest-carbohydrate, stress-carbohydrate (randomized cross-over design). Stress was induced by means of a psychological computer-test. The test-meal was either a high-protein meal (En% P/C/F 65/5/30) or a high-carbohydrate meal (En% P/C/F 6/64/30), both meals were matched for energy density (4 kJ/g) and daily energy requirements (30%). Per test-session salivary cortisol levels, appetite profile, mood state and level of anxiety were measured. High hunger, low satiety (81 ± 16, 12 ± 15 mm VAS) confirmed the fasted state. The stress condition was confirmed by increased feelings of depression, tension, anger, anxiety (AUC stress vs. rest p < 0.02). Consumption of the high-protein vs. high-carbohydrate meal did not affect feelings of depression, tension, anger, anxiety. Cortisol levels did not differ between the four test-sessions in men and women (AUC nmol·min/L p > 0.1). Consumption of the test-meals increased cortisol levels in men in all conditions (p < 0.01), and in women in the rest-protein and stress-protein condition (p < 0.03). Men showed higher cortisol levels than women (AUC nmol·min/L p < 0.0001). Consumption of meals with different macronutrient contents, i.e. high-protein vs. high-carbohydrate, does not influence the physiological and psychological response differentially. Men show a higher meal-induced salivary cortisol response compared with women.     

Threshold of airway response to inhaled methacholine in healthy men and women

Threshold of airway response to inhaled methacholine was determined using maximum expiratory partial flow-volume curves in 21 men and 36 women with similar age distribution, all of them healthy nonsmokers. Mean threshold was on average 1.3 doubling dose lower in women than men. There were no sex differences in the increase of maximum expiratory flows after a full inspiration when the airways were constricted by methacholine.     

Effect of glucose and of insulin on the fast induced decrease of insulin response to glucose of the in vitro perfused rat pancreas]

A 24 hours fast decreases by 50% the first and second phases of insulin response to glucose by the isolated and perfused rat pancreas, while the response to tolbutamide remains unchanged. Intra peritoneal administration of low doses of glucose (0.3 g), four times during fasting restored the insulin response. Administration of insulin (0.25 U x 4). Tolbutamide (1.25 mg x 4) or L-leucine (0.1 g x 4), did not. These results show that an exogenous or endogenous insulin impregnation is not the factor responsible for the maintenance of the B cell gluco-receptor during fasting.     

Short-term and long-term effects of guar on postprandial plasma glucose, insulin and glucagon-like peptide 1 concentration in healthy rats.

Ingestion of guar gum decreases postprandial glycemia and insulinemia and improves sensitivity to insulin in diabetic patients and several animal models of diabetes. The aim of the present study was to compare the short-term and long-term effects of guar on plasma insulin and glucagon-like peptide 1 concentration in healthy rats. In the short-term experiments, the concomitant intragastric administration of glucose and guar reduced the early increment in plasma glucose, insulin and glucagon-like peptide 1 concentration otherwise induced by glucose alone. Comparable findings were made after twelve days of meal training exposing the rats to either a control or guar-enriched diet for fifteen minutes. Mean plasma glucose concentrations were lower while mean insulin concentrations were higher in the guar group than in the controls according to intragastric glucose tolerance tests conducted in overnight fasted rats maintained for 19 to 36 days on either the control or guar-enriched diet. The intestinal content of glucagon-like peptide 1 at the end of the experiments was also lower in the guar group. Changes in body weight over 62 days of observation were comparable in the control and guar rats. Thus, long-term intake of guar improves glucose tolerance and insulin response to glucose absorption, without improving insulin sensitivity, in healthy rats.     

Intravenous glucose tolerance, insulin response to glucose, peripheral sensitivity to insulin, and serum lipoproteins in post-myocardial infarct patients with normal fasting blood glucose

Intravenous glucose tolerance (IVGTT), basal insulin and insulin response to glucose infusion (GIT), insulin sensitivity, and lipoprotein patterns were determined in non-obese post-coronary subjects, 3-6 months after myocardial infarction. Twelve had decreased and 31 normal IVGTT. The control group comprised 31 subjects with normal IVGTT, who did not display any signs of coronary disease. The post-coronary patients were not taking any drugs except for furosamide, which was shown not to influence insulin response to GIT or glucose tolerance. Decreased IVGTT in the post-coronary patients could be ascribed to decreased insulin response and insulin resistance. These two derangements are considered as hereditary markers in glucose intolerance and type 2 diabetes. Accordingly, our findings suggest that glucose intolerance in subjects with myocardial infarcts has the same background. The post-coronary patients demonstrated elevated triglycerides (TG) and cholesterol in total serum and in very low density lipoproteins (VLDL), the lipoprotein patterns being almost identical in post-coronary patients with or without decreased IVGTT. No relationship was found in the control and post-coronary groups between IVGTT, basal insulin, stimulated insulin (KI, IP), and insulin sensitivity (KG), on the one hand, and total or VLDL TG or any other lipoprotein particle, on the other. Thus, the derangements in glucose, insulin, and serum triglyceride metabolism were independent abnormalities (risk factors) in these non-obese post-coronary patients.     

Genioglossus muscle activity at rest and in response to brief hypoxia in healthy men and women.

Obstructive sleep apnea (OSA) is more common in men than in women for reasons that are not clearly understood. An underlying difference between men and women in the respiratory-related neural control of upper airway dilator muscles has been suggested as a possible reason for the gender difference. We have compared three aspects of upper airway dilator muscle function in healthy men and women: 1) resting inspiratory genioglossus electromyogram (EMGgg) activity, 2) the respiratory EMGgg "afterdischarge" after a brief hypoxic stimulus, and 3) the relationship between the EMGgg and pharyngeal airway pressure. Inspired minute ventilation (VI), epiglottic pressure (P(epi)), and EMGgg and diaphragm EMG (EMGdi) activity were measured in 24 subjects (12 men, 12 women in the luteal menstrual phase) and were compared between genders while lying supine awake. Every 7-8 min over 2 h, subjects were exposed to 45-s periods of isocapnic hypoxia (9% O(2) in N(2)) that were abruptly terminated with one breath of 100% O(2). The relationship between P(epi) and EMGgg activity was also compared between genders. The results of 117 trials with satisfactory end-tidal PCO(2) control and no sighs or swallows are reported. There was no gender difference in the resting level of peak inspiratory EMGgg [3.7 +/- 0.8 (women) vs. 3.2 +/- 0.6% maximal activity (men)]. Repeated-measures ANOVA showed no gender or gender-by-time interaction effect between men and women in VI or EMGgg or EMGdi activity during or after the hypoxic stimulus. The relationship between P(epi) and EMGgg was not different between men (slope -0.63 +/- 0.20) and women (slope -0.69 +/- 0.33). These results do not support the hypothesis that the higher prevalence of OSA in men is related to an underlying gender difference in respiratory neural control of upper airway dilator muscles.     

Plasma zinc response to a breakfast meal or fasting in elderly women

The aim of this study was to determine whether the postprandial decline in plasma zinc concentration is altered by aging. Eleven women, between the ages of 65 and 82 yr, participated in two separate experimental protocols: a high carbohydrate breakfast trial and a fasting trial. Plasma zinc concentrations were measured from blood samples obtained at 8∶00am (baseline fasting) and at 30-min intervals until 1∶00pm during each trial. Following the breakfast meal, plasma zinc concentrations declined 14% from 75±1 to 65±2 μg/dL (p<0.05), reaching a nadir 2.7±0.2 h after the meal. This decline was significantly (p<0.0001) greater than the 3.6% fall observed during the fasting trial. Postprandial changes in the plasma zinc concentrations were correlated with postprandial changes in serum glucose (r=−0.43,p<0.001), serum insulin (r=−0.17,p<0.01), and serum phosphorus(r=0.32,p<0.005). These data show that plasma zinc concentrations decline following food intake in elderly women in the same manner as previously described for younger adult women.     

Effects of fasting on insulin action and glucose kinetics in lean and obese men and women

The development of insulin resistance in the obese individual could impair the ability to appropriately adjust metabolism to perturbations in energy balance. We investigated a 12- vs. 48-h fast on hepatic glucose production (R(a)), peripheral glucose uptake (R(d)), and skeletal muscle insulin signaling in lean and obese subjects. Healthy lean [n = 14; age = 28.0 +/- 1.4 yr; body mass index (BMI) = 22.8 +/- 0.42] and nondiabetic obese (n = 11; age = 34.6 +/- 2.3 yr; BMI = 36.1 +/- 1.5) subjects were studied following a 12- and 48-h fast during 2 h of rest and a 3-h 40 mUxm(-2)xmin(-1) hyperinsulinemic-euglycemic clamp (HEC). Basal glucose R(a) decreased significantly from the 12- to 48-h fast (lean 1.96 +/- 0.23 to 1.63 +/- 0.15; obese 1.23 +/- 0.07 to 1.07 +/- 0.07 mgxkg(-1)xmin(-1); P = 0.004) and was equally suppressed during the HEC after both fasts. The increase in glucose R(d) during the HEC after the 12-h fast was significantly decreased in lean and obese subjects after the 48-h fast (lean 9.03 +/- 1.17 to 4.16 +/- 0.34, obese 6.10 +/- 0.77 to 3.56 +/- 0.30 mgxkg FFM(-1)xmin(-1); P < 0.001). After the 12- but not the 48-h fast, insulin-stimulated AKT Ser(473) phosphorylation was greater in lean than obese subjects. We conclude that 1) 48 h of fasting produces a marked decline in peripheral insulin action, while suppression of hepatic glucose production is maintained in lean and obese men and women; and 2) the magnitude of this decline is greater in lean vs. obese subjects.     

Blood flow response to a postural challenge in older men and women

BACKGROUND: The purpose of this study was to measure blood flow in the carotid and femoral arteries, heart rate and blood pressure in response to postural challenge in older adults. A second purpose was to determine if older men and women have different cardiovascular responses to a postural challenge such as tilt. METHODS: Thirty-seven healthy elderly men and women participated in this study (69-82 years old). All subjects had similar physical activity levels. Postural challenge was induced by a 60 degrees tilt at the level of the waist. Continuous carotid blood flow and femoral blood flow was measured with Doppler ultrasound. RESULTS: Carotid blood flow was significantly reduced 17% in both men and women immediately after tilt (p < 0.001), and by 3.2% two minutes after tilt (p < 0.001). Femoral blood flow decreased 59.4% in men and 61% in women immediately after tilt (p < 0.001), and remained significantly decreased two minutes after tilt by 21% (p <0.001). Heart rate increased by 15% in men (p < 0.001), and 26% in women immediately after the tilt (p < 0.001). Heart rate returned to resting values within two minutes in both men and women. Response to tilt was not significantly related to self-report physical activity levels or to six-minute walk time. CONCLUSION: A postural challenge induced larger changes in the femoral artery compared to the carotid artery. There were no differences between men and women to a tilt table test except for differences in heart rate response. There was no difference in the blood flow responses to postural challenge with physical activity level or between healthy older men and women.