The effects of a diet rich in inulin or wheat fibre on markers of cardiovascular disease in overweight male subjects.

BACKGROUND: Previous studies suggest that the beneficial health effects of a diet rich in whole grains could be a result of the individual fibres found in the grain. The present study aimed to investigate the influence of a diet high in either wheat fibre (as an example of an insoluble fibre) or inulin (a nondigestible carbohydrate) on markers of cardiovascular disease. METHODS: Ten male participants classified as at higher risk of cardiovascular disease [mean (SD) body mass index 30.2 (3) kg m(-2) , mean (SD) waist circumference 106.4 (7) cm, mean (SD) age 39.8 (9) years] were recruited to a randomised, controlled, cross-over study comparing the consumption of bespoke bread rolls containing either inulin, wheat germ or refined grain (control) (15 g day(-1) ) for 4 weeks with a 4-week washout period between each regime. At the end of each regime, participants underwent an oral glucose tolerance test (OGTT), measures of pulse wave velocity (PWV), 24-h ambulatory blood pressure (AMBP), plasma lipid status and markers of glucose control. RESULTS: There was no difference in measures of glucose control, lipid status, 24-h AMBP or PWV after the intervention periods and no changes compared to baseline. There was no significant difference between OGTT glucose and insulin time profiles; however, there was a significant difference in area under the curves between the wheat fibre and control interventions when comparing change from baseline (control +10.2%, inulin +4.3%, wheat fibre -2.5%; P = 0.03). CONCLUSIONS: Only limited differences between the interventions were identified, perhaps as a consequence of the amount of fibre used and intervention length. The wheat germ intervention resulted in a significant reduction in glucose area under the curve, suggesting that this fibre may aid glucose control.

Influence of the tolerability of vinegar as an oral source of short-chain fatty acids on appetite control and food intake.

BACKGROUND: Vinegar is promoted as a natural appetite suppressant, based on previous reports that vinegar ingestion significantly increases subsequent satiety. However there are concerns about the appropriateness and safety of this advice, and it is unclear if poor product palatability may explain previously published effects on appetite. OBJECTIVE: To investigate if vinegar palatability and tolerability have a role in suppressing appetite and food intake in two sequential and related acute human feeding studies. SUBJECTS AND METHODS: Healthy, young, normal weight unrestrained eaters were recruited to Study 1 (n=16), an acute feeding study supplying vinegar within both palatable and unpalatable drinks alongside a mixed breakfast in comparison to a non-vinegar control; and to Study 2 (n=14), a modified sham feeding study (taste only without ingestion) comparing vinegar to a non-vinegar control following a milkshake preload. Both studies were a randomized crossover balanced design for the assessment of appetite, energy intake and glycaemic response. RESULTS: In Study 1, ingestion of vinegar significantly reduced quantitative and subjective measures of appetite, which were accompanied by significantly higher nausea ratings, with unpalatable treatment having the greatest effect. Significant correlations between palatability ratings and appetite measures were found. In Study 2, orosensory stimulation with vinegar did not influence subsequent subjective or quantitative measures of appetite compared with control. CONCLUSIONS: These studies indicate that vinegar ingestion enhances satiety whereas orosensory stimulation alone does not, and that these effects are largely due to poor tolerability following ingestion invoking feelings of nausea. On this basis the promotion of vinegar as a natural appetite suppressant does not seem appropriate.

Low glycaemic index diets and blood lipids: a systematic review and meta-analysis of randomised controlled trials.

AIMS: Low glycaemic index (GI) diets are beneficial in the management of hyperglycemia. Cardiovascular diseases are the major cause of mortality in diabetes therefore it is important to understand the effects of GI on blood lipids. The aim was to systematically review randomised controlled trials (RCTs) of low GI diets on blood lipids. DATA SYNTHESIS: We searched OVID Medline, Embase and Cochrane library to March 2012. Random effects meta-analyses were performed on twenty-eight RCTs comparing low- with high GI diets over at least 4 weeks (1272 participants; studies ranged from 6 to 155 participants); one was powered on blood lipids, 3 had adequate allocation concealment. Low GI diets significantly reduced total (-0.13 mmol/l, 95%CI -0.22 to -0.04, P = 0.004, 27 trials, 1441 participants, I(2) = 0%) and LDL-cholesterol (-0.16 mmol/l, 95%CI -0.24 to -0.08, P < 0.0001, 23 trials, 1281 participants, I(2) = 0%) compared with high GI diets and independently of weight loss. Subgroup analyses suggest that reductions in LDL-C are greatest in studies of shortest duration and greatest magnitude of GI reduction. Furthermore, lipid improvements appear greatest and most reliable when the low GI intervention is accompanied by an increase in dietary fibre. Sensitivity analyses, removing studies without adequate allocation concealment, lost statistical significance but retained suggested mean falls of ~0.10 mmol/l in both. There were no effects on HDL-cholesterol (MD -0.03 mmol/l, 95%CI -0.06 to 0.00, I(2) = 0%), or triglycerides (MD 0.01 mmol/l, 95%CI -0.06 to 0.08, I(2) = 0%). CONCLUSIONS: This meta-analysis provides consistent evidence that low GI diets reduce total and LDL-cholesterol and have no effect on HDL-cholesterol or triglycerides.

Resistant starch improves insulin sensitivity in metabolic syndrome.

AIMS: Diets rich in non-viscous fibre are linked to a reduced risk of both diabetes and cardiovascular disease; however, the mechanism of action remains unclear. This study was undertaken to assess whether chronic consumption of this type of fibre in individuals with the metabolic syndrome would improve insulin sensitivity via changes in ectopic fat storage. METHODS: The study was a single-blind, randomized, parallel nutritional intervention where 20 insulin resistant subjects consumed either the fibre supplement (resistant starch) (40 g/day) or placebo supplement (0 g/day) for 12 weeks. Insulin sensitivity was measured by euglycaemic-hyperinsulinaemic clamp and ectopic fat storage measured by whole-body magnetic resonance spectroscopy. RESULTS: Resistant starch consumption did not significantly affect body weight, fat storage in muscle, liver or visceral depots. There was also no change with resistant starch feeding on vascular function or markers of inflammation. However, in subjects randomized to consume the resistant starch, insulin sensitivity improved compared with the placebo group (P = 0.023). Insulin sensitivity correlated significantly with changes in waist circumference and fat storage in tibialis muscle and to a lesser extent to visceral-to-subcutaneous abdominal adipose tissue ratio. CONCLUSION: Consumption of resistant starch improves insulin sensitivity in subjects with the metabolic syndrome. Unlike in animal models, diabetes prevention does not appear to be directly related to changes in body adiposity, blood lipids or inflammatory markers. Further research to elucidate the mechanisms behind this change in insulin sensitivity in human subjects is required.

Long-term cost-effectiveness of weight management in primary care.

BACKGROUND: As obesity prevalence and health-care costs increase, Health Care providers must prevent and manage obesity cost-effectively. METHODS: Using the 2006 NICE obesity health economic model, a primary care weight management programme (Counterweight) was analysed, evaluating costs and outcomes associated with weight gain for three obesity-related conditions (type 2 diabetes, coronary heart disease, colon cancer). Sensitivity analyses examined different scenarios of weight loss and background (untreated) weight gain. RESULTS: Mean weight changes in Counterweight attenders was -3 kg and -2.3 kg at 12 and 24 months, both 4 kg below the expected 1 kg/year background weight gain. Counterweight delivery cost was pound59.83 per patient entered. Even assuming drop-outs/non-attenders at 12 months (55%) lost no weight and gained at the background rate, Counterweight was 'dominant' (cost-saving) under 'base-case scenario', where 12-month achieved weight loss was entirely regained over the next 2 years, returning to the expected background weight gain of 1 kg/year. Quality-adjusted Life-Year cost was pound2017 where background weight gain was limited to 0.5 kg/year, and pound2651 at 0.3 kg/year. Under a 'best-case scenario', where weights of 12-month-attenders were assumed thereafter to rise at the background rate, 4 kg below non-intervention trajectory (very close to the observed weight change), Counterweight remained 'dominant' with background weight gains 1 kg, 0.5 kg or 0.3 kg/year. CONCLUSION: Weight management for obesity in primary care is highly cost-effective even considering only three clinical consequences. Reduced healthcare resources use could offset the total cost of providing the Counterweight Programme, as well as bringing multiple health and Quality of Life benefits.

Inflammatory disease processes and interactions with nutrition.

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain omega-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (omega-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

Leucine-enriched essential amino acid supplementation in mechanically ventilated trauma patients: a feasibility study.

BACKGROUND: Critically ill patients lose up to 2% of muscle mass per day. We assessed the feasibility of administering a leucine-enriched essential amino acid (L-EAA) supplement to mechanically ventilated trauma patients with the aim of assessing the effect on skeletal muscle mass and function. METHODS: A randomised feasibility study was performed over six months in intensive care (ICU). Patients received 5 g L-EAA five times per day in addition to standard feed (L-EAA group) or standard feed only (control group) for up to 14 days. C-reactive protein, albumin, IL-6, IL-10, urinary 3-MH, nitrogen balance, protein turnover ([1-13C] leucine infusion), muscle depth change (ultrasound), functional change (Katz and Barthel indices) and muscle strength Medical Research Council (MRC) sum score to assess ICU Acquired Weakness were measured sequentially. RESULTS: Eight patients (9.5% of screened patients) were recruited over six months. L-EAA doses were provided on 91/124 (73%) occasions. Inflammatory and urinary marker data were collected; serial muscle depth measurements were lacking due to short length of stay. Protein turnover studies were performed on five occasions. MRC sum score could not be performed as patients were not able to respond to the screening questions. The Katz and Barthel indices did not change. L-EAA delivery was achievable, but meaningful functional and muscle mass outcome measures require careful consideration in the design of a future randomised controlled trial. CONCLUSION: L-EAA was practical to provide, but we found significant barriers to recruitment and measurement of the chosen outcomes which would need to be addressed in the design of a future, large randomised controlled trial. TRIAL REGISTRATION: ISRCTN Registry, ISRCTN79066838 . Registered on 25 July 2012.

The effect of a 12-week low glycaemic index diet on heart disease risk factors and 24 h glycaemic response in healthy middle-aged volunteers at risk of heart disease: a pilot study.

OBJECTIVE: To compare the effects of two energy-restricted healthy diets, one with a low GI and one with a high GI, on heart disease risk factors and weight loss in subjects at risk of heart disease. DESIGN: A 12-week randomized parallel study of low and high GI, healthy eating diets was carried out. SETTING: The study was carried out at the Hammersmith Hospital. SUBJECTS: Eighteen subjects were recruited by advertisement and randomized to one of the two diets. Fourteen completed the study but one was excluded from the final analysis. METHODS: At randomization, subjects were advised to follow the intervention diet for 12 weeks. Before randomization and on completion of the study, anthropometrics, fasting cholesterol and glucose blood tests and 24-h glucose measurements were taken using a continuous glucose monitoring system (CGMS). Statistical analysis was carried out using non-parametric tests. Median (IQR) are presented. RESULTS: A significantly different dietary GI was achieved in the low GI (median: 51.3 (IQR: 51.0-52.0) compared to the high GI (59.3 (59.2-64.0) (P=0.032) group. By week 12, both groups reduced their energy intake by: low GI group: (-)167 ((-)312-(-)123) kcal/day (P=0018) vs high GI group: (-)596 ((-)625-(-)516) (P=0.018) kcal/day, the difference between the groups being significant (P=0.010). However, only the low GI group lost weight ((-)4.0 ((-)4.4-(-)2.4) kg (P=0.018) whereas the high GI group did not significantly change in weight ((-)1.5 ((-)3.6-0.8) kg (P=0.463). By week 12, the low GI group also had a significantly lower 24-h area under the curve (AUC) (7556 (7315-8434) vs 8841 (8424-8846) mmol-h/l (P=0.045) and overnight AUC (2429 (2423-2714) vs 3000 (2805-3072) mmol-h/l (P=0.006) glucose as measured by CGMS. There were no differences in the other heart disease risk factors assessed. CONCLUSIONS: This pilot study provides some evidence that consuming a low GI diet in addition to weight loss and healthy eating may reduce cardiovascular risk. Other potential benefits of GI might have been masked by weight loss in the low GI group. Larger-scale studies need to follow.

Glucagon-like peptide-1 (7-36) amide response to low versus high glycaemic index preloads in overweight subjects with and without type II diabetes mellitus.

BACKGROUND AND OBJECTIVE: Glucagon-like-peptide-1 (7-36) amide (GLP-1) is an insulin secretagogue and potential treatment for type II diabetes mellitus. An alternative to GLP-1 administration is endogenous dietary stimulation. We described a greater GLP-1 release following ingestion of liquids versus solids. We add to this work studying the effect of fluid preloads with differing glycaemic indices (GI) on the metabolic response to a meal. SUBJECTS AND DESIGN: GLP-1, insulin and glucose responses were measured in six overweight individuals and six subjects with type II diabetes on three occasions, after preload (milk, low GI; Ovaltine Light, high GI; or water, non-nutritive control) and meal ingestion. RESULTS: In people with and without diabetes, the high GI preload produced the greatest glucose incremental area under the curve (IAUC)(0-20), followed by the low GI preload, and water (P<0.001). In both groups, insulin IAUC(0-20) was higher following high and low GI preloads compared with water (NS). In people without diabetes, the GLP-1 response was higher when high and low GI preloads were consumed compared with water (P=0.041), with no significant difference between nutritive preloads. GLP-1 response did not differ between preloads in people with diabetes. Despite initial differences, total IAUCs(0-200) for biochemical variables did not differ by preload. CONCLUSION: We confirm that nutritive liquids stimulate GLP-1 to a greater extent than water in subjects without diabetes; however, this does not influence subsequent meal-induced response. The GI of preloads does not influence the degree of GLP-1 stimulation.

Failure of dietetic referral in patients with gastrointestinal cancer and weight loss.

This study examined whether staff working within a cancer centre treating patients with gastrointestinal malignancy routinely identified individuals from outpatients for referral to a dietitian. A nutrition screening tool is employed only for in-patient admissions. Height, current and usual weight were recorded prospectively in all patients referred for consideration of treatment. First appointment with the dietitian, first hospital admission, demographic and clinical details were obtained from hospital records. Time from first appointment to referral to a dietitian was examined. Between September 2002 and March 2004, 920 patients were included. Five hundred and seventeen patients had lost weight, of whom 223 patients had lost between 5% and 10% and 294 patients had lost more than 10% of their pre-morbid weight. Three hundred and twenty-seven patients (36%) were referred to dietitians. Twenty eight (9%) of referrals were made by staff in outpatients. Two hundred and ninety-nine were referred during or after an inpatient admission but only 39% of these occurred within the first seven days following admission. One third of patients with more than 10% weight loss were not referred for dietary assessment, even following admission. The likelihood of referral was significantly associated with the degree of weight loss (univariate analysis hazard ratio (HR) 1.75, 95% Confidence Interval (CI) 1.4-2.19, multivariate HR 1.65, 95% CI 1.22-2.23) and was independent of factors such as performance status and clinical setting. Few patients were identified early in their treatment for referral to a dietitian. Since most chemotherapy is now given on an outpatient basis, patients are unlikely to be referred if they do not require admission. This study suggests that an out-patient dietetic screening tool is urgently required. Such screening is likely to result in considerable improvements to the clinical care of cancer patients with weight loss.

Ghrelin stimulates insulin-induced glucose uptake in adipocytes.

The gastric and hypothalamic hormone ghrelin is the endogenous agonist of the growth hormone secretagogue receptor GHS-R1(a). Ghrelin stimulates growth hormone release and appetite via the hypothalamus. However, putative direct peripheral effects of ghrelin remain poorly understood. Rat adipose tissue expresses GHS-R1(a) mRNA, suggesting ghrelin may directly influence adipocyte function. We have investigated the effects of ghrelin on insulin-stimulated glucose uptake in isolated white adipocytes in vitro. RT-PCR confirmed the expression of GHS-R1(a) mRNA in epididymal adipose tissue. However, GHS-R1(a) expression was not detected in the peri-renal fat pads. Ghrelin increased insulin-stimulated deoxyglucose uptake in isolated white adipocytes extracted from the epididymal fat pads of male Wistar rats. Ghrelin 1000 nM significantly increased deoxyglucose uptake by 55% in the presence of 0.1 nM insulin. However, ghrelin administration in the absence of insulin had no effect on adipocyte deoxyglucose uptake, suggesting that ghrelin acts synergistically with insulin. Des-acyl ghrelin, a major circulating non-octanylated form of ghrelin, had no effect on insulin-stimulated glucose uptake. Furthermore, acylated ghrelin had no effect on deoxyglucose uptake in adipocytes from peri-renal fat pads suggesting that ghrelin may influence glucose uptake via the GHS-R1(a). Ghrelin therefore appears to directly potentiate adipocyte insulin-stimulated glucose uptake in selective adipocyte populations. Ghrelin may play a role in adipocyte regulation of glucose homeostasis.

Randomised clinical study: inulin short-chain fatty acid esters for targeted delivery of short-chain fatty acids to the human colon.

BACKGROUND: Short-chain fatty acids (SCFA) produced through fermentation of nondigestible carbohydrates by the gut microbiota are associated with positive metabolic effects. However, well-controlled trials are limited in humans. AIMS: To develop a methodology to deliver SCFA directly to the colon, and to optimise colonic propionate delivery in humans, to determine its role in appetite regulation and food intake. METHODS: Inulin SCFA esters were developed and tested as site-specific delivery vehicles for SCFA to the proximal colon. Inulin propionate esters containing 0-61 wt% (IPE-0-IPE-61) propionate were assessed in vitro using batch faecal fermentations. In a randomised, controlled, crossover study, with inulin as control, ad libitum food intake (kcal) was compared after 7 days on IPE-27 or IPE-54 (10 g/day all treatments). Propionate release was determined using (13) C-labelled IPE variants. RESULTS: In vitro, IPE-27-IPE-54 wt% propionate resulted in a sevenfold increase in propionate production compared with inulin (P < 0.05). In vivo, IPE-27 led to greater (13) C recovery in breath CO2 than IPE-54 (64.9 vs. 24.9%, P = 0.001). IPE-27 also led to a reduction in energy intake during the ad libitum test meal compared with both inulin (439.5 vs. 703.9 kcal, P = 0.025) and IPE-54 (439.5 vs. 659.3 kcal, P = 0.025), whereas IPE-54 was not significantly different from inulin control. CONCLUSIONS: IPE-27 significantly reduced food intake suggesting colonic propionate plays a role in appetite regulation. Inulin short-chain fatty acid esters provide a novel tool for probing the diet-gut microbiome-host metabolism axis in humans.

Veganism and its relationship with insulin resistance and intramyocellular lipid.

OBJECTIVE: To test the hypothesis that dietary factors in the vegan diet lead to improved insulin sensitivity and lower intramyocellular lipid (IMCL) storage. DESIGN: Case-control study. SETTING: Imperial College School of Medicine, Hammersmith Hospital Campus, London, UK. SUBJECTS: A total of 24 vegans and 25 omnivores participated in this study; three vegan subjects could not be matched therefore the matched results are shown for 21 vegans and 25 omnivores. The subjects were matched for gender, age and body mass index (BMI). INTERVENTIONS: Full anthropometry, 7-day dietary assessment and physical activity levels were obtained. Insulin sensitivity (%S) and beta-cell function (%B) were determined using the homeostatic model assessment (HOMA). IMCL levels were determined using in vivo proton magnetic resonance spectroscopy; total body fat content was assessed by bioelectrical impedance. RESULTS: There was no difference between the groups in sex, age, BMI, waist measurement, percentage body fat, activity levels and energy intake. Vegans had a significantly lower systolic blood pressure (-11.0 mmHg, CI -20.6 to -1.3, P=0.027) and higher dietary intake of carbohydrate (10.7%, CI 6.8-14.5, P<0.001), nonstarch polysaccharides (20.7 g, CI 15.8-25.6, P<0.001) and polyunsaturated fat (2.8%, CI 1.0-4.6, P=0.003), with a significantly lower glycaemic index (-3.7, CI -6.7 to -0.7, P=0.01). Also, vegans had lower fasting plasma triacylglycerol (-0.7 mmol/l, CI -0.9 to -0.4, P<0.001) and glucose (-0.4 mmol/l, CI -0.7 to -0.09, P=0.05) concentrations. There was no significant difference in HOMA %S but there was with HOMA %B (32.1%, CI 10.3-53.9, P=0.005), while IMCL levels were significantly lower in the soleus muscle (-9.7, CI -16.2 to -3.3, P=0.01). CONCLUSION: Vegans have a food intake and a biochemical profile that will be expected to be cardioprotective, with lower IMCL accumulation and beta-cell protective.

Empowering primary care to tackle the obesity epidemic: the Counterweight Programme.

OBJECTIVE: To improve the management of obese adults (18-75 y) in primary care. DESIGN: Cohort study. SETTINGS: UK primary care. SUBJECTS: Obese patients (body mass index > or =30 kg/m(2)) or BMI> or =28 kg/m(2) with obesity-related comorbidities in 80 general practices. INTERVENTION: The model consists of four phases: (1) audit and project development, (2) practice training and support, (3) nurse-led patient intervention, and (4) evaluation. The intervention programme used evidence-based pathways, which included strategies to empower clinicians and patients. Weight Management Advisers who are specialist obesity dietitians facilitated programme implementation. MAIN OUTCOME MEASURES: Proportion of practices trained and recruiting patients, and weight change at 12 months. RESULTS: By March 2004, 58 of the 62 (93.5%) intervention practices had been trained, 47 (75.8%) practices were active in implementing the model and 1549 patients had been recruited. At 12 months, 33% of patients achieved a clinically meaningful weight loss of 5% or more. A total of 49% of patients were classed as 'completers' in that they attended the requisite number of appointments in 3, 6 and 12 months. 'Completers' achieved more successful weight loss with 40% achieving a weight loss of 5% or more at 12 months. CONCLUSION: The Counterweight programme provides a promising model to improve the management of obesity in primary care.

Pancreatic polypeptide reduces appetite and food intake in humans.

Pancreatic polypeptide (PP) is a gut hormone released from the pancreas in response to ingestion of food. Plasma PP has been shown to be reduced in conditions associated with increased food intake and elevated in anorexia nervosa. In addition peripheral administration of PP has been shown to decrease food intake in rodents. These findings suggest that PP may act as a circulating factor that regulates food intake. Therefore we investigated the effect of intravenous infusion of PP (10 pmol/kg/min) on appetite and food intake in a randomised double-blind placebo-controlled crossover study in ten healthy volunteers. Infusion of PP reduced appetite and decreased the energy intake at a buffet lunch two hours post-infusion by 21.8 +/- 5.7% (P < 0.01). More importantly the inhibition of food intake was sustained, such that energy intake, as assessed by food diaries, was significantly reduced both the evening of the study and the following morning. Overall PP infusion reduced cumulative 24-hour energy intake by 25.3 +/- 5.8%. In conclusion our data demonstrates that PP causes a sustained decrease in both appetite and food intake.

Ghrelin enhances appetite and increases food intake in humans.

Ghrelin is a recently identified endogenous ligand for the growth hormone secretagogue receptor. It is synthesized predominantly in the stomach and found in the circulation of healthy humans. Ghrelin has been shown to promote increased food intake, weight gain and adiposity in rodents. The effect of ghrelin on appetite and food intake in man has not been determined. We investigated the effects of intravenous ghrelin (5.0 pmol/kg/min) or saline infusion on appetite and food intake in a randomised double-blind cross-over study in nine healthy volunteers. There was a clear-cut increase in energy consumed by every individual from a free-choice buffet (mean increase 28 +/- 3.9%, p<0.001) during ghrelin compared with saline infusion. Visual analogue scores for appetite were greater during ghrelin compared to saline infusion. Ghrelin had no effect on gastric emptying as assessed by the paracetamol absorption test. Ghrelin is the first circulating hormone demonstrated to stimulate food intake in man. Endogenous ghrelin is a potentially important new regulator of the complex systems controlling food intake and body weight.

Diet-induced change in fatty acid composition of plasma triacylglycerols is not associated with change in glucagon-like peptide 1 or insulin sensitivity in people with type 2 diabetes.

BACKGROUND: Polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs) have been shown to positively affect blood lipids; however, their comparative effects on insulin sensitivity are unclear. OBJECTIVE: Our objective was to investigate whether chronic intake of MUFAs or PUFAs improves insulin sensitivity in people with type 2 diabetes via stimulation of the endogenous gut hormone glucagon-like peptide 1 [7-36] amide (GLP-1). DESIGN: Nine overweight people with type 2 diabetes received isoenergetic high-MUFA (20.3 +/- 3.5% of total energy) or high-PUFA (13.4 +/- 1. 3%) diets for 24 d in a randomized, double-blind crossover design. RESULTS: Weight and glycemic control remained stable throughout the study. Despite a significant change in the plasma triacylglycerol linoleic-oleic acid ratio (L:O) with both diets (MUFA: from 0.46 +/- 0.03 to 0.29 +/- 0.02, P: < 0.005; PUFA: from 0.36 +/- 0.04 to 0.56 +/- 0.05, P: < 0.05) and the phospholipid L:O (1.7 +/- 0.1 to 2.0 +/- 0.3; P: = 0.04) during consumption of the PUFA diet, this change was not associated with a change in insulin sensitivity, measured by the short-insulin-tolerance test. There was a significant reduction in the ratio of total to HDL cholesterol during consumption of the PUFA diet (5.2 +/- 0.4 compared with 4.7 +/- 0.3; P: = 0.005) but no change with the MUFA diet. There was no change in the fasting or postprandial incremental area under the curve in response to an identical standard test meal for glucose, insulin, triacylglycerol, nonesterified fatty acids, or GLP-1. CONCLUSIONS: Over the 3-wk intervention period, diet-induced change in the triacylglycerol or phospholipid L:O was not associated with either increased stimulation of GLP-1 or a change in insulin sensitivity in people with type 2 diabetes.

A prospective randomised trial to determine the efficacy of a low glycaemic index diet given in addition to healthy eating and weight loss advice in patients with coronary heart disease.

OBJECTIVE: Recent epidemiological and prospective trial evidence suggests that consumption of a low glycaemic index (LGI) diet will reduce coronary risk. We hypothesise that introduction of an LGI diet will improve the metabolic profile of patients who have undergone coronary artery bypass grafting. DESIGN: We conducted a randomised parallel group trial comparing a control group (n=29, age 61.8+/-9 y), who received currently advocated healthy eating dietary advice only, to an intervention group, who received healthy eating advice emphasising LGI carbohydrates (n=26, age 63.6+/-9.4 y) over a 12-week period in free-living patients with coronary heart disease. Outcome measures included fasting glucose, insulin, total cholesterol, high-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides. RESULTS: A significant lower dietary glycaemic index was achieved in the group assigned to an LGI diet compared to the healthy eating control group (71+/-1 vs 81+/-1); fibre intake was also higher in the LGI group (20+/-1 vs 15+/-1 g). All biochemical markers of glucose and lipid metabolism measured were similar after 12 weeks of the LGI diet or control diet. DISCUSSION: The LGI group achieved a significant LGI and a higher dietary fibre intake. However, there was no measurable significant effect of either the LGI diet or the health eating diet on lipid levels; this may have been hidden by concurrent drug therapy.

The effects of fiber enrichment of pasta and fat content on gastric emptying, GLP-1, glucose, and insulin responses to a meal.

OBJECTIVE: To assess whether the addition of viscous fiber at an amount recommended by the US FDA to allow a 'low saturated fat, cholesterol, soluble fiber and coronary heart disease', health claim label on a food package (1.7 g psyllium) and/or fat (30 g sunflower oil and 3 g sodium propionate) to a pasta meal would affect gastric emptying, postprandial glucose, insulin and GLP-1 concentrations. DESIGN: Ten subjects participated in a two-by-two single blind randomized crossover study. Four meals containing 50 g of available carbohydrate were consumed: pasta with or without psyllium enrichment served with a tomato sauce with (520 kcal per meal) and without (240 kcal per meal) fat. Blood samples were taken for 240 min following the meal and all subjects consumed a buffet meal at the end of the study. Gastric emptying was measured using the paracetamol absorption test. Blood was analysed for glucose, insulin, GLP-1. Visual analog scales were used to record feelings of hunger, pleasantness and nausea. RESULTS: The psyllium-enriched pasta had no significant effect on gastric emptying or the incremental area under the curve (IAUC) for GLP-1, insulin or glucose compared with the control pasta. The addition of polyunsaturated fat and sodium propionate significantly increased the IAUC for GLP-1 (P<0.001), delaying gastric emptying (P<0.002), and decreasing glucose (P<0.002). CONCLUSIONS: A dose of 1.7 g psyllium did not evoke measurable effects on gastric emptying, postprandial GLP-1, insulin or glucose metabolism. However the addition of 30 g of oil and 3 g of sodium propionate to the pasta did reduce gastric emptying, increase GLP-1 and reduce glucose and insulin concentrations. While this short-term study may have implications in terms of reducing the risk of diabetes and improving coronary risk factor profiles the long term effects of these nutrients need to be studied.

Plasma glucagon-like peptide-1 (7-36) amide (GLP-1) response to liquid phase, solid phase, and meals of differing lipid composition.

The gut hormone glucagon-like peptide-1 (7-36) amide (GLP-1) is a potent insulin secretagogue. It has been proposed to be a novel treatment for non-insulin-dependent diabetes mellitus (NIDDM). Postprandial plasma GLP-1, insulin, and glucose responses were measured in six healthy volunteers in response to a solid test meal and a liquid meal of identical composition. Responses to three isocaloric soups of identical macronutrient and energy content containing differing degrees of fat saturation were also measured. The liquid form of the meal released significantly more GLP-1 than the solid form (measured by incremental area under the curve 0-180 min: 2.5 nmol.min-1.L-1 [median]; range 1.4-3.7 versus 1.4 nmol.min-1.L-1 [median]; range 0.6-1.8) (P < 0.05) and this occurred earlier (15 min versus 60 min). The incremental area under the curve for insulin was significantly greater following the liquid meal (incremental area under the curve 0-180 min: 18.5 nmol.min-1.L-1 [median]; range 15.9-35.8 versus 17.6 nmol.min-1.L-1 [median]; range 13.7-25.5) (P < 0.05). The glucose response to each meal was not different. The type of fat in the soups produced no significant difference in GLP-1, insulin, or glucose levels. Our findings suggest that the physical form of a meal significantly alters the GLP-1 response, whereas fatty acid saturation has little effect.