Kerin O'Dea

Arabinoxylan fibre improves metabolic control in people with Type II diabetes

Objective: To determine whether diet supplementation with arabinoxylan-rich (AX)-fibre from wheat improves glycaemic control in Type II diabetes.Design: Randomized, crossover intervention trial.Setting: Monash Medical Centre.Subjects: A total of 15 subjects with Type II diabetes.Interventions: Over two 5-week periods, subjects supplemented their usual diet with control bread and muffins (50% whole wheat, 50% white flour) (control diet) or with AX-bread and muffins (50% whole wheat, 36% white flour, 14% AX fibre) (AX diet). Subjects completed a 7-day food diary. At 0 and 5 weeks, venous blood was collected for determination of fasting and 2 h glucose, insulin, fructosamine and blood lipids. Blood pressure, body weight and body fat were also determined. A 24 h faecal sample, from 12 subjects, was weighed and analysed for faecal polysaccharide as a marker for dietary compliance.Results: Control and AX diets were similar except the AX diet supplied an additional 15.1 (12.0–18.5) (mean (95% confidence intervals)) g/day dietary fibre (P=0.000). Consumption of the AX diet increased faecal output by 61.5 (0.2–122.8) g/day (P=0.05) on a wet weight basis and significantly lowered fasting and 2 h plasma glucose, 2 h insulin and serum fructosamine (P=0.002, 0.000, 0.015, and 0.02, respectively). Blood lipids, body weight, fat mass and blood pressure remained unchanged.Conclusions: A supplement of 15 g/day of AX-rich fibre can significantly improve glycaemic control in people with Type II diabetes.Sponsorship: Food Science Australia, Melbourne; George Weston Foods Ltd, Sydney.

Determinants of restenosis and lack of effect of dietary supplementation with eicosapentaenoic acid on the incidence of coronary artery restenosis after angioplasty

The effect of an eicosapentaenoic acid-rich encapsulated preparation of fish oil on the incidence of early restenosis after coronary angioplasty was assessed by a randomized double-blind placebo-controlled study. A total of 108 patients received either 10 capsules of fish oil (1.8 g eicosapentaenoic acid, 1.2 g docosahexaenoic acid) or 10 control capsules (50% olive oil, 50% corn oil), commencing the day before angioplasty and continuing for 4 months after angioplasty, in addition to treatment with aspirin and verapamil. In 101 (94%) of the 108 patients, follow-up angiographic or postmortem result was evaluated at a mean (+/- SD) of 100 (+/- 22) days. Angiographic restenosis was observed in 34% of patients (29% of lesions) in the fish oil-treated group and 33% of patients (31% of lesions) in the control group (no significant difference). The overall incidence of angiographic restenosis was significantly higher in patients with 1) recurrent angina pectoris, 2) a positive exercise test at follow-up after angioplasty, 3) residual stenosis greater than 30% immediately after angioplasty, and 4) dilation of the left anterior descending or right coronary artery. Biochemical investigations showed a greater decrease in the serum triglyceride levels in the fish oil-treated group versus the control group (p less than 0.05) but no differences between the two groups in cholesterol levels or platelet counts over the 4 month period. In conclusion, in this study, the administration of fish oil at a dose of 10 capsules/day did not reduce the incidence of early restenosis after coronary angioplasty.

The influence of the type of dietary fat on postprandial fat oxidation rates: monounsaturated (olive oil) vs saturated fat (cream)

Objective: To compare postprandial whole-body fat oxidation rates in humans, following high-fat (43% of total energy) mixed breakfast meals, of fixed energy and macronutrient composition, rich in either monounsaturated fat (MUFA) from extra virgin olive oil or saturated fat (SFA) from cream.Design: Paired comparison of resting metabolic rate (RMR), thermic effect of a meal and substrate oxidation rates following consumption of isocaloric breakfast meals, differing only in the type of fat, administered in random order 1–2 weeks apart.Subjects: Fourteen male volunteers, body mass index (BMI) in the range 20–32 kg/m2, aged 24–49 y and resident in Melbourne, Australia, were recruited by advertisement in the local media or by personal contact.Measurements: Body size and composition was determined by anthropometry and dual energy X-ray absorptiometry (DEXA). Indirect calorimetry was used to measure RMR, thermic effect of a meal, post-meal total energy expenditure and substrate oxidation rate. Blood pressure and pulse rates were measured with an automated oscillometric system. Fasting and 2 h postprandial glucose and insulin concentrations and the fasting lipid profile were also determined.Results: In the 5 h following the MUFA breakfast, there was a significantly greater postprandial fat oxidation rate (3.08±4.58 g/5 h, P=0.017), and lower postprandial carbohydrate oxidation rate (P=0.025), than after the SFA breakfast. Thermic effect of a meal was significantly higher (55 kJ/5 h, P=0.034) after the MUFA breakfast, in subjects with a high waist circumference (HWC≥99 cm) than those with a low waist circumference (LWC<99 cm). This difference was not detected following the SFA breakfast (P=0.910).Conclusion: If postprandial fat oxidation rates are higher after high MUFA, rather than SFA meals, then a simple change to the type of dietary fat consumed might have beneficial effects in curbing weight gain in men consuming a relatively high-fat diet. This may be particularly evident in men with a large waist circumference.

Indirect estimates of body composition are useful for groups but unreliable in individuals.

OBJECTIVE: To assess the usefulness of the body mass index (BMI) in identifying individuals classified as overweight or obese based on estimates of body fat percentage (BF%) obtained by the deuterium dilution (BF%DD) method. In addition, to assess the accuracy of bioelectrical impedance analysis (BIA) and skinfold thickness (SFT) measurements in the estimation of body composition of Australians at the individual and group level.DESIGN: Cross-sectional study.SUBJECTS: One hundred and seventeen healthy Australian volunteers of European descent, comprising of 51 males and 66 females, ranging in age from 19 to 77 y.MEASUREMENTS: BMI was calculated from body weight and height. Fat-free mass (FFM) was estimated from measures of total body water (TBW) using deuterium dilution (FFMDD), SFT using the equations of Durnin and Womersley (Br J Nutr 1974; 32: 77–97) (FFMSFT), and BIA using the equations of Lukaski et al (J Appl Physiol 1986; 60: 1327–1332) (FFMLU), Segal et al (Am J Clin Nutr 1988; 47: 7–14) (FFMSe) and Heitmann (Eur J Clin Nutr 1990; 44: 831–837) (FFMHe). Estimates of fat mass (FM) were calculated as the difference between body weight and FFM, while BF% was calculated by expressing FM as a percentage of body weight.RESULTS: BMI had poor sensitivity and positive predictive value in identifying individuals as being overweight/obese as classified by BF%DD. Furthermore, estimates of FFM (and hence FM) from BIA or SFT could not be used interchangeably with DD, without the risk of considerable error at the individual level. At the group level errors were relatively smaller, though statistically significant. While FFMSFT could be corrected by the addition of the bias (1.2 kg in males and 0.8 kg in females), no simple correction was possible with BIA estimates of FFM for any of the equations used. However, an accurate prediction of FFMDD was possible from the combination of FFMHe, biceps SFT and mid-arm circumference in both males and females. The bias of this prediction was small (<0.15 kg), statistically non-significant in both sexes, and unrelated to the mean FFM obtained by the two methods. The revision of Heitmanns estimate of FFM using anthropometric variables described in this study had the best sensitivity (79%), specificity (96%) and positive predictive value (92%) in identifying overweight/obese individuals in comparison to the other equations tested.CONCLUSION: BMI was a poor surrogate for body fatness in both males and females. The currently recommended equations for the prediction of body composition from SFT and BIA provided inaccurate estimates of FFM both at the individual and group level as compared to estimates from DD. However, Heitmanns equations, when combined with measures of the biceps SFT and mid-arm circumference, provided better estimates of FFM both at the individual and group level.

Substitution of saturated with monounsaturated fat in a 4-week diet affects body weight and composition of overweight and obese men.

A randomised crossover study of eight overweight or obese men (aged 24-49 years, BMI 25.5-31.3 kg/m(2)), who followed two diets for 4 weeks each, was performed to determine whether substitution of saturated fat with monounsaturated fat affects body weight and composition. Subjects were provided with all food and beverages as modules (selected ad libitum) of constant macronutrient composition, but differing energy content. The % total energy from saturated fat, monounsaturated fat and polyunsaturated fat was 24, 13 and 3 % respectively on the saturated fatty acid (SFA)-rich diet and 11, 22 and 7 % respectively on the monounsaturated fatty acid (MUFA)-rich diet. MUFA accounted for about 80 % of the unsaturated fats consumed on both diets. Body composition, blood pressure, energy expenditure (resting and postprandial metabolic rates, substrate oxidation rate, physical activity), serum lipids, the fatty acid profile of serum cholesteryl esters and plasma glucose and insulin concentrations were measured before and after each diet period. Significant (P< or =0.05) differences in total cholesterol and the fatty acid composition of serum cholesteryl esters provided evidence of dietary adherence. The men had a lower weight (-2.1 (SE 0.4) kg, P=0.0015) and fat mass (-2.6 (SE 0.6) kg, P=0.0034) at the end of the MUFA-rich diet as compared with values at the end of the SFA-rich diet. No significant differences were detected in energy or fat intake, energy expenditure, substrate oxidation rates or self-reported physical activity. Substituting dietary saturated with unsaturated fat, predominantly MUFA, can induce a small but significant loss of body weight and fat mass without a significant change in total energy or fat intake.

BENEFICIAL IMPACT OF THE HOMELANDS MOVEMENT ON HEALTH OUTCOMES IN CENTRAL AUSTRALIAN ABORIGINES

Objective: This study compares prevalence of obesity, hypertension and diabetes in two groups of Aboriginal adults: those living in homelands versus centralised communities in central Australia. It also compares weight gain, incidence of diabetes, mortality and hospitalisation rates between the groups over a seven‐year period.

Obesity, Diabetes, and Hyperlipidemia in a Central Australian Aboriginal Community With a Long History of Acculturation

Objective— To determine the age- and sex-specific prevalence of diabetes and to examine associations between related anthropometric and metabolic abnormalities in an Aboriginal community in central Australia with a long history of acculturation. Research Design and Methods— We used a cross-sectional survey of 353 adults > 15 yr of age (87% response rate) and measured the following parameters: weight, height, circumferences of waist and hips; glucose, insulin, cholesterol, triglyceride, and high-density lipoprotein cholesterol in fasting plasma; and plasma glucose and insulin 2 h after 75 g oral glucose. Results— The prevalence of diabetes was 29.6% in survey participants > 35 yr of age and 5.3% in those < 35 yr of age. Impaired glucose tolerance also occurred with higher frequency in those > 35 yr of age (14.8 vs. 4.7%). Of those > 35 yr of age, 75% of the women and 51% of the men were overweight or obese, with a body mass index ≥ 25 kg/m2. A large insulin response to oral glucose was evident, with the upper tertile of the 2-h insulin response six times higher than the lower tertile (113 ± 43 vs. 19 ± 8 mU/L). Hyperinsulinemia showed a strong, positive association with impaired glucose tolerance, body mass index, waist-to-hip ratio, cholesterol, and triglyceride levels and a negative association with high-density lipoprotein cholesterol levels. Cholesterol levels were on average 0.5 mM higher in men than in women. Deteriorations in carbohydrate and lipid metabolism occurred before 40 yr of age: diabetes, body mass index, waist-to-hip ratio, and fasting triglycerides and cholesterol concentrations peaked and high-density lipoprotein cholesterol concentrations reached their nadir at the end of the fourth decade. Conclusions— These data suggest that any intervention programs developed to prevent or reduce diabetes prevalence in this population should be targeted at adolescents and young adults.

Measuring Prevalence: Obesity, diabetes and associated cardiovascular risk factors among Torres Strait Islander people

Objective:To describe the lifestyle‐related chronic disease and risk factor prevalence among Torres Strait Islander people of the Torres Strait and Northern Peninsula Area Health Service District and to compare this information with that available for the general Australian population.

Alcohol intake, consumption pattern and beverage type, and the risk of Type 2 diabetes.

Aims  To examine associations between amount and frequency of alcohol consumption, and Type 2 diabetes.

Evaluation of brief dietary questions to estimate vegetable and fruit consumption - using serum carotenoids and red-cell folate

OBJECTIVE To evaluate responses to self-administered brief questions regarding consumption of vegetables and fruit by comparison with blood levels of serum carotenoids and red-cell folate. DESIGN A cross-sectional study in which participants reported their usual intake of fruit and vegetables in servings per day, and serum levels of five carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene) and red-cell folate were measured. Serum carotenoid levels were determined by high-performance liquid chromatography, and red-cell folate by an automated immunoassay system. SETTINGS AND SUBJECTS Between October and December 2000, a sample of 1598 adults aged 25 years and over, from six randomly selected urban centres in Queensland, Australia, were examined as part of a national study conducted to determine the prevalence of diabetes and associated cardiovascular risk factors. RESULTS Statistically significant (P<0.01) associations with vegetable and fruit intake (categorised into groups: </=1 serving, 2-3 servings and >/=4 servings per day) were observed for alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and red-cell folate. The mean level of these carotenoids and of red-cell folate increased with increasing frequency of reported servings of vegetables and fruit, both before and after adjusting for potential confounding factors. A significant association with lycopene was observed only for vegetable intake before adjusting for confounders. CONCLUSIONS These data indicate that brief questions may be a simple and valuable tool for monitoring vegetable and fruit intake in this population.