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.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3639-2) contains supplementary material, which is available to authorized users.

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.

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.

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.

Effects of a novel propionate-rich sourdough bread on appetite and food intake

BACKGROUND

There is evidence linking oral propionate to a reduction in food intake, which could confer functional food properties in the fight against obesity. However, propionate is typically volatile with a pungent smell and taste and so incorporating into foods naturally, at levels acceptable to the consumer is a novel approach.

SUBJECTS/METHODS

Twenty healthy, young, normal weight unrestrained eaters underwent an acute feeding study using a palatable sourdough and an identical control bread of a similar palatability, in a randomized cross-over balanced design for the assessment of appetite and energy intake.

RESULTS

No difference in energy intake of an ad libitum test meal, 180 min after the bread-based breakfast or in energy and macronutrient intake over the entire 24 h period was found between breads. Visual analogue scale ratings for appetite were not influenced by bread type, except the desire to eat something sweet. Elevated plasma insulin concentrations were observed following the propionate-rich sourdough breakfast (P=0.033 no effects of treatment on postprandial glycaemia were found.

CONCLUSIONS

These findings suggest propionate-rich sourdough bread does not influence appetite and food intake unlike larger doses of the food preservative N-propionate.

Genetic predisposition influences plasma lipids of participants on habitual diet, but not the response to reductions in dietary intake of saturated fatty acids

OBJECTIVE

SNPs identified from genome-wide association studies associate with lipid risk markers of cardiovascular disease. This study investigated whether these SNPs altered the plasma lipid response to diet in the 'RISCK' study cohort.

METHODS

Participants (n=490) from a dietary intervention to lower saturated fat by replacement with carbohydrate or monounsaturated fat, were genotyped for 39 lipid-associated SNPs. The association of each individual SNP, and of the SNPs combined (using genetic predisposition scores), with plasma lipid concentrations was assessed at baseline, and on change in response to 24 weeks on diets.

RESULTS

The associations between SNPs and lipid concentrations were directionally consistent with previous findings. The genetic predisposition scores were associated with higher baseline concentrations of plasma total (P=0.02) and LDL (P=0.002) cholesterol, triglycerides (P=0.001) and apolipoprotein B (P=0.004), and with lower baseline concentrations of HDL cholesterol (P<0.001) and apolipoprotein A-I (P<0.001). None of the SNPs showed significant association with the reduction of plasma lipids in response to the dietary interventions and there was no evidence of diet-gene interactions.

CONCLUSION

Results from this exploratory study have shown that increased genetic predisposition was associated with an unfavourable plasma lipid profile at baseline, but did not influence the improvement in lipid profiles by the low-saturated-fat diets.

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.

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.

Low-dose oral tri-iodothyronine does not directly increase food intake in man

Previously, we have shown that low-dose tri-iodothyronine (T3) increases food intake in rodents. This randomised, double-blind, placebo-controlled study aimed to investigate the effects of low-dose T3 on food intake in normal body weight individuals. However, despite an elevation in fT3 comparable to our earlier studies, administration of low-dose T3 in the fasted state did not stimulate food intake in man.

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.

Vulnerable patients with a fractured neck of femur: nutritional status and support in hospital

BACKGROUND AND AIM

Malnutrition has serious consequences for recovery and increases the risk of complications in hospital patients. Fractured neck of femur (NOF) patients may be particularly at risk because of their old age and frail state of health. We conducted an observational study to evaluate the nutritional state and the nutritional support, which was provided to this group during their stay in hospital.

METHODS

Twenty-five consecutive people admitted to an orthopaedic ward with a fractured NOF at Charing Cross Hospital, London were recruited. Anthropometric measures, biochemical indices, 3 days dietary intake and dietetic referral rates were collected.

RESULTS

Patients had a significantly lower body mass index (BMI) compared with the mean BMI for sex and age in an elderly UK population (21.97 +/- 1.06 versus 26.73 +/- 0.03 kg m(-2); P < 0.005). They took just 58.6% of their energy requirements in hospital (4219 +/- 319 versus 7199 +/- 202 kJ mean(-1) daily intake over 3 days in week 2). Using the hospitals own nutritional risk assessment tool 56% of patients were found to be at risk of malnutrition on admission, which increased to 68% after 2-3 weeks. Of these 64% were referred to a dietitian and were given nutritional supplements. Nutritional assessment revealed that their nutritional status worsened during stay.

CONCLUSIONS

This group of patients with fractured NOF is likely to be malnourished on admission and to show a rapid deterioration in its nutrition status during admission. Energy needs were not met in up to 50% of patients. These results reinforce the need to screen, supplement and monitor fractured NOF patients.

Oxyntomodulin increases energy expenditure in addition to decreasing energy intake in overweight and obese humans: a randomised controlled trial

BACKGROUND

Oxyntomodulin has recently been found to decrease body-weight in obese humans and may be a potential anti-obesity therapy.

OBJECTIVE

To determine whether oxyntomodulin alters energy expenditure, in addition to reducing energy intake, in 'free-living' overweight and obese volunteers.

DESIGN

Randomized double-blind controlled cross-over trial.

SETTING

Community and hospital-based.

PARTICIPANTS

Fifteen healthy overweight and obese men and women (age: 23-49 years, BMI: 25.1-39.0 kg/m(2)). All volunteers completed the study protocol.

INTERVENTIONS

Four-day subcutaneous self-administration of pre-prandial oxyntomodulin, three times daily. Participants were advised to maintain their normal dietary and exercise regimen.

MEASUREMENTS

(1) Energy expenditure, measured by indirect calorimetry and combined heart rate and movement monitoring; (2) energy intake, measured during a study meal.

RESULTS

Oxyntomodulin administration reduced energy intake at the study meal by 128+/-29 kcal (P=0.0006) or 17.3+/-5.5% (P=0.0071), with no change in meal palatability. Oxyntomodulin did not alter resting energy expenditure; but increased activity-related energy expenditure by 143+/-109 kcal/day or 26.2+/-9.9% (P=0.0221); total energy expenditure by 9.4+/-4.8% (P=0.0454) and physical activity level by 9.5+/-4.6% (P=0.0495). A reduction in body weight of 0.5+/-0.2% was observed during the oxyntomodulin administration period (P=0.0232).

CONCLUSION

Oxyntomodulin increases energy expenditure while reducing energy intake resulting in negative energy balance. This data supports the role of oxyntomodulin as a potential anti-obesity therapy.

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.

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.

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.

Retrospective analysis of the impact of a low glycaemic index diet on hospital stay following coronary artery bypass grafting: a hypothesis

OBJECTIVE

Glucose tolerance and insulin resistance influence medical outcome in subjects with coronary artery disease, these metabolic parameters also influence general perioperative surgical outcome. We hypothesize that glucose tolerance and insulin resistance can be favourably modified by reducing the glycaemic index of the diet.

DESIGN

The present study is a retrospective analysis of a low and high glycaemic index diet on glucose tolerance, insulin resistance and perioperative outcome, as assessed by the length of hospital stay following coronary artery bypass surgery. Thirty-five adults awaiting bypass surgery were randomized, for the 4 weeks prior to surgery, to either a low glycaemic index diet (17 subjects) or high glycaemic index diet (18 subjects). Glucose and insulin responses during a 75 g oral glucose tolerance test were assessed before and after dietary intervention and insulin-mediated glucose uptake was assessed in isolated adipocytes obtained at surgery.

RESULTS

The patients who consumed a low glycaemic diet had improved glucose tolerance and significantly greater in vitro adipocyte insulin sensitivity at the time of surgery compared with the high glycaemic diet group (78.87 +/- 10.64% versus 41.11 +/- 7%, respectively). The total length of stay in the patients on the low glycaemic diet was less than patients consuming the high glycaemic diet (7.06 +/- 0.38 days versus 9.53 +/- 1.44 days, P < 0.5).

CONCLUSION

This study provides further support that carbohydrate and fat metabolism influence cardiac outcome and provides new evidence that dietary modification prior to coronary artery bypass surgery can shorten hospital stay.

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.

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.

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.

Neurovascular disease, antioxidants and glycation in diabetes

People with diabetes are ten to fifteen times more likely to have a lower limb amputation (LLA) than non-diabetic individuals. Fifteen percent of people with diabetes will develop a foot ulcer during their lifetime, the rate of major amputation amongst diabetic individuals continues to rise, foot problems remain the commonest reason for diabetes-related hospitalisation and recurrence rates in patients with previous foot ulcers are 50% or more. Hyperglycaemia-induced oxidative stress has been shown to result in decreased nerve conduction velocity, and decreased endoneural blood flow-both precursors for neuropathy. Vitamin antioxidants have been shown to be effective therapy in experimental models in reducing free radical species and inhibiting the oxidative process in diabetes subjects. Little work has been published, however, regarding the dietary use of antioxidants from foods, and their specific effects on neurovascular disease and glycation within the diabetes population. Aetiological and prevention studies with dietary antioxidants from foods aimed at the complex nature of foot problems in diabetes are needed.

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.

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.

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.

Exendin-4 reduces fasting and postprandial glucose and decreases energy intake in healthy volunteers

Exendin-4 is a long-acting potent agonist of the glucagon-like peptide 1 (GLP-1) receptor and may be useful in the treatment of type 2 diabetes and obesity. We examined the effects of an intravenous infusion of exendin-4 (0.05 pmol. kg(-1). min(-1)) compared with a control saline infusion in healthy volunteers. Exendin-4 reduced fasting plasma glucose levels and reduced the peak change of postprandial glucose from baseline (exendin-4, 1.5 +/- 0.3 vs. saline, 2.2 +/- 0.3 mmol/l, P < 0.05). Gastric emptying was delayed, as measured by the paracetamol absorption method. Volunteers consumed 19% fewer calories at a free-choice buffet lunch with exendin-4 (exendin-4, 867 +/- 79 vs. saline 1,075 +/- 93 kcal, P = 0.012), without reported side effects. Thus our results are in accord with the possibility that exendin-4 may be a potential treatment for type 2 diabetes, particularly for obese patients, because it acts to reduce plasma glucose at least partly by a delay in gastric emptying, as well as by reducing calorie intake.

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.

The glycaemic index of a range of gluten-free foods

AIMS

The number of people with both diabetes and coeliac disease is increasing. This study examined the effect of gluten-free, as opposed to gluten-replete carbohydrate containing foods, on post-prandial blood glucose concentrations.

METHODS

The glycaemic index of six commonly used gluten-free carbohydrates are reported and compared with published figures for similar non-gluten-free products.

RESULTS

The results indicate that the glycaemic index of gluten-free and gluten containing foods are similar.

CONCLUSIONS

The inclusion of gluten-free foods in the diet of diabetic individuals with coeliac disease should not compromise glycaemic control.

Sibutramine is effective for weight loss and diabetic control in obesity with type 2 diabetes: a randomised, double-blind, placebo-controlled study

AIM

To assess the efficacy and tolerability of sibutramine 15 mg once daily as a weight reduction agent in overweight and obese patients (body mass index (b.m.i.) > 26 kg/m2) with type 2 diabetes when given with a customised, reduced-calorie diet, and to evaluate the influence of weight loss on diabetic control.

METHODS

Randomised, placebo-controlled, double-blind, parallel-group, 12-week study conducted at two hospital-based obesity/diabetes clinics. Patients were men and women aged 30-65 years, with b.m.i. > 26 kg/m2 and < or = 35 kg/m2 and treated or untreated type 2 diabetes diagnosed > or = 6 months previously. Each patient was given sibutramine 15 mg or placebo once daily and advised to follow a customised diet of 500 kcal/day less than the individual's energy needs. The principal measure of efficacy was change in body weight (b.w.). Additional efficacy measurements were changes in b.m.i., body composition as measured by dual-energy X-ray absorptiometry, and change in waist and hip measurements. Changes in diabetic control were assessed by blood glucose levels fasting and after a standard test meal, fasting insulin level, and glycosylated haemoglobin level. Adverse events (AEs) were monitored at each visit, and routine laboratory safety tests were done at 4-week intervals.

RESULTS

Ninety-one patients were randomised into the study, 44 to placebo and 47 to sibutramine 15 mg once daily. Eighty-three patients (91%) completed the study, 40 (91%) on placebo and 43 (91%) on sibutramine. Mean weight reduction from baseline was statistically significantly greater with sibutramine than with placebo at every measurement and at the end of the study (2.4 vs. 0.1 kg at week 12; p < 0.001; intent-to-treat). The proportion of patients who lost > 5% of their baseline b.w. was 19% in the sibutramine group and 0% in the placebo group (p < 0.001; 95% confidence interval: 9, 30). Patients receiving sibutramine lost significantly more fat mass compared with those receiving placebo, as a percentage (1.0% vs. 0.1%; p < 0.05) and in absolute terms (1.8 vs. 0.2 kg, p < 0.001). Loss of lean mass was not significantly different between the groups. Mean peak blood glucose concentration after a standard test meal decreased by 1.1 mmol/l in the sibutramine treatment group but increased by 0.5 mmol/l in the placebo group (p = 0.04; difference in means, 1.6, 95% confidence interval: -3.3, -0.1). Mean fasting blood glucose decreased by 0.3 mmol/l with sibutramine and increased by 1.4 mmol/l with placebo. Mean glycosylated haemoglobin levels decreased by 0.3% units with sibutramine treatment, and were unchanged with placebo. However, more sibutramine-treated patients (33%) than placebo-treated patients (5%) achieved decreases in glycosylated haemoglobin of 1% unit or more (p < 0.05). Sibutramine 15 mg was safe and well tolerated, and AEs were mostly mild or moderate in severity. No significant differences were found between treatment groups in blood pressure. No clinically significant conduction or rhythm abnormalities were observed on ECG.

CONCLUSIONS

Sibutramine 15 mg once daily with a customised, reduced-calorie diet significantly reduced weight compared with placebo in overweight and obese patients (b.m.i. > 26 kg/m2) with type 2 diabetes. Sibutramine was well tolerated, and significant improvement in diabetic control was seen in conjunction with weight reduction on sibutramine treatment.

Reduced adipocyte insulin sensitivity in Caucasian and Asian subjects with coronary heart disease

The association between insulin resistance and coronary heart disease (CHD) is strong in the British Indian-Asian population. Adipocyte metabolism may contribute to both insulin resistance and CHD. We examined insulin-stimulated glucose uptake in adipocytes and in vivo insulin sensitivity using the fasting insulin resistance index (FIRI) in 60 subjects (45 Caucasian and 15 Asian) with CHD and 30 Caucasian subjects without CHD. In 25 CHD subjects (18 Caucasian and 7 Asian), the relationship between adipocyte insulin sensitivity and non-esterified fatty acid (NEFA) suppression to oral glucose was examined. Compared with controls, the CHD subjects had higher values of fasting insulin [51 (46 to 54) pmol l(-1) vs 36 (31 to 41) pmol l(-1) p< 0.01] and FIRI [1.65 (1.5 to 1.79) vs 1.06 (0.89 to 1.23), p < 0.01]. Among the CHD subjects, the Asians had higher values than Caucasian [insulin 58 (48 to 67) pmol l(-1) vs 48 (44 to 53) pmol l(-1) p < 0.01, FIRI 1.89 (1.44 to 2.13) vs 1.62 (1.4 to 1.79), p< 0.01)]. Insulin-stimulated glucose uptake in adipocytes was lower in the CHD than control subjects [56 (50 to 62) vs 115 (75 to 132) attomol min(-1).mm2, p < 0.05], being most reduced among the Asians. It was positively correlated with postprandial NEFA suppression and negatively with insulin release. In conclusion, abnormalities of adipocyte function and insulin sensitivity occur in CHD and may contribute to its aetiology.

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.

Biliary excretion, systemic availability and reactivity of metabolites following intraportal infusion of [3H]benzo[a]pyrene in the rat

Following the intraportal infusion of [3H]benzo[a]pyrene (BP) at two dose levels (5 and 0.125 mumol/kg) in the rat, metabolites were excreted via the bile and were released into the hepatic venous blood. At each dose level, a significant portion (approx. 15-18%) of biliary metabolites was directly extractable with ethyl acetate and a total of approx. 24-32% became extractable after incubation of bile with beta-glucuronidase. More than 65% and 70% of the 3H in blood and liver, respectively, was directly extractable with ethyl acetate. The h.p.l.c. profile of extracted metabolites was found to differ at the two dose levels studied. The binding of reactive metabolites to hepatic protein and DNa was measured at four dose levels of [3H]BP. The possible availability of hepatic-derived metabolites to extra-hepatic sites is discussed.