Homocysteine concentrations lowered following dietary intervention in an aboriginal community

Low circulating folate concentrations lead to elevations of plasma homocysteine. Even mild elevations of plasma homocysteine are associated with significantly increased risk of cardiovascular disease (CVD). Available evidence suggests that poor nutrition contributes to excessive premature CVD mortality in Australian Aboriginal people. The aim of the present study was to examine the effect of a nutrition intervention program conducted in an Aboriginal community on plasma homocysteine concentrations in a community-based cohort. From 1989, a health and nutrition project was developed, implemented and evaluated with the people of a remote Aboriginal community. Plasma homocysteine concentrations were measured in a community-based cohort of 14 men and 21 women screened at baseline, 6 months and 12 months. From baseline to 6 months there was a fall in mean plasma homocysteine of over 2|mol/L (P = 0.006) but no further change thereafter (P = 0.433). These changes were associated with a significant increase in red cell folate concentration from baseline to 6 months (P < 0.001) and a further increase from 6 to 12 months (P < 0.001). In multiple regression analysis, change in homocysteine concentration from baseline to 6 months was predicted by change in red cell folate (P = 0.002) and baseline homocysteine (P < 0.001) concentrations, but not by age, gender or baseline red cell folate concentration. We conclude that modest improvements in dietary quality among populations with poor nutrition (and limited disposable income) can lead to reductions in CVD risk.

Low plasma concentrations of diet-derived antioxidants in association with microalbuminuria in Indigenous Australian populations

Microalbuminuria is a risk factor for renal and cardiovascular diseases. Oxidant stress may contribute to vascular disease risk by promoting damage to renal and vascular tissues. This study examined the associations of plasma levels of diet-derived antioxidants with albuminuria in Australian population groups at high risk of renal and cardiovascular disease. Data on microalbuminuria and diet-derived plasma antioxidants were drawn from results of cross-sectional community-based risk factor surveys of Aboriginal and Torres Strait Islander peoples (n =698, 15 years and older). Prevalence of microalbuminuria ranged from 17-21%. After adjustment for age, gender, body mass index, diabetes, smoking status, plasma lipids and blood pressure, microalbuminuria was associated with significantly lower plasma concentrations of lycopene (-29%; P <0.001), beta-carotene (-22%; P <0.001), alpha-carotene (-22%; P <0.001) and cryptoxanthin (-17%; P <0.001) compared with normalbuminuric persons. Significant associations of microalbuminuria with plasma concentrations of alpha-tocopherol, retinol, lutein plus zeaxanthin and homocysteine were absent. The data are consistent with a protective effect of diets rich in carotenoids on vascular endothelium and/or renal tissues, and support the need for interventions to address affordable food supplies and dietary quality among Indigenous Australians.

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.

Paraoxonase and other coronary risk factors in a community-based cohort

Oxidative damage to circulating lipids and vascular tissues contributes to the initiation and progression of atherosclerosis. High density lipoprotein provides protection from atherosclerosis and the enzyme paraoxonase may contribute to this effect. The aim of the present study was to examine the trends in paraoxonase activity during the course of a community-directed life-style intervention, and relationships of paraoxonase activity to other coronary heart disease risk factors, in a cohort of Australian Aboriginal people.

Relation of adiposity and body fat distribution to body mass index in Australians of Aboriginal and European ancestry

OBJECTIVE

To compare the relations of adiposity and body fat distribution to body mass index (BMI) in Australians of Aboriginal and European ancestry.

DESIGN

Cross-sectional volunteer samples.

SETTING

Australian Aboriginal communities in remote central and northern Australia, urban European Australians resident in Melbourne, Australia.

SUBJECTS

Healthy Aboriginal (130 women, 120 men) and European Australians (100 women, 47 men) with a BMI<30 kg/m(2), aged 18-35 y; all women were nonpregnant.

INTERVENTIONS

Anthropometric variables and resistance-using a four-terminal impedance plethysmograph-were measured.

RESULTS

Aboriginal women and men were significantly shorter and weighed less than European Australians (P<0.05). Aboriginal women had a significantly larger waist circumference and waist-to-hip ratio (WHR, P<0.0005) compared to European Australian women. The sum of four skinfold thicknesses (SFT) (S4) and trunk SFT was higher in Aboriginals as compared to European Australian women (P<0.0005); however, limb SFT tended to be lower (P=0.06). On the other hand, BMI was significantly lower in Aboriginals compared to European Australian men (P=0.011), as was hip circumference (P=0.001); however, WHR was significantly (P=0.007) higher. On regression analysis, Aboriginal women and men were significantly heavier than European Australians for the same height(2)/resistance (surrogate for fat-free mass) and S4 (surrogate for subcutaneous fat); and that Aboriginal men had a significantly higher BMI (by 1.2 kg/m(2); P<0.0005) for any given S4 and height(2)/resistance values, compared to European Australian men.

CONCLUSION

Aboriginal and European Australians have a significantly different body fat distribution and fat mass for a given body weight or BMI. Use of the World Health Organization recommended BMI ranges to determine weight status may be inappropriate in Australian Aboriginal people.

Inflammation and vascular endothelial activation in an Aboriginal population: relationships to coronary disease risk factors and nutritional markers

OBJECTIVE

To describe the levels of inflammation and vascular endothelial activation in an Aboriginal community, and the relationship of these factors to coronary heart disease (CHD) risk factors and markers of nutritional quality.

DESIGN AND PARTICIPANTS

A cross-sectional survey of 95 women and 76 men participating in a chronic-disease prevention program.

SETTING

A remote Aboriginal community in Western Australia in 1996.

MAIN OUTCOME MEASURES

Concentrations of markers of inflammation (C-reactive protein [CRP]) and vascular endothelial activation (soluble E-selectin [sE-selectin]); presence of metabolic syndrome; concentrations of diet-derived antioxidants.

RESULTS

Participants exhibited very high plasma concentrations of CRP (mean, 5.4 mg/L; 95% CI, 4.6-6.3 mg/L) and sE-selectin (mean, 119 ng/mL; 95% CI, 111-128 ng/mL). Both CRP and sE-selectin concentrations were significantly higher in the presence of the metabolic syndrome. There were significant inverse linear relationships between concentrations of CRP and plasma concentrations of the antioxidants lycopene, beta-carotene, cryptoxanthin and retinol. Even stronger inverse associations were evident between concentrations of sE-selectin and lycopene, beta-carotene, cryptoxanthin and lutein.

CONCLUSIONS

Vascular inflammation and endothelial activation may be important mediators of elevated CHD risk in Aboriginal people. Inadequate nutrition and physical inactivity may contribute to this process.

Association of albuminuria and the metabolic syndrome

Microalbuminuria clusters with the metabolic syndrome, and both conditions predict cardiovascular disease mortality. The reported relationships of microalbuminuria with the individual components of the metabolic syndrome (i.e., hyperglycemia, insulin resistance, hypertension, dyslipidemia, abdominal obesity) are variable. Each of these components, as well as intrauterine effects and diet and other lifestyle factors, may contribute to elevated risk of microalbuminuria in certain population groups. Recent evidence indicates a role for oxidation and inflammation in cardiovascular disease, and endothelial dysfunction (exacerbated by factors such as dyslipidemia) may be the mediator of this relationship. Because endothelial dysfunction can also be manifested as microalbuminuria, this provides a potential explanation of the observed association of the metabolic syndrome, chronic inflammation, and microalbuminuria.

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil

OBJECTIVE

To characterize the carotenoid content of selected components of the Mediterranean diet commonly eaten by Greek migrants to Melbourne, a population group maintaining a traditional dietary regimen, and who exhibit relatively high circulating carotenoid concentrations and low cardiovascular disease mortality. DESIGN AND SPECIMENS: Opportunistic sampling of wild (sow thistle, amaranth, purslane and dandelion, collected from roadsides and home gardens) and commercially available (chicory, endive) green leafy vegetables and figs in season. Foods were selected on the basis that they are commonly eaten by Greek migrants but not by Anglo-Celtic persons, and had not previously been well-characterized with respect to their carotenoid contents. Extra virgin, cold-pressed olive oil and 'extra light' olive oil were obtained from commercial sources. Specimens were extracted with tetrahydrofuran (or chloroform:methanol for olive oil) and carotenoid contents were quantified using HPLC with UV detection. Two to six specimens of greens and figs were analysed. Dietary intake was assessed by food frequency questionnaire.

RESULTS

Wild green vegetables contained high concentrations of lutein (sow thistle>amaranth>purslane>dandelion) and beta-carotene (sow thistle>amaranth>purslane=dandelion). Sow thistle and amaranth contained lutein (15 and 13 mg/100 g, respectively) and beta-carotene (3.3 and 4.0 mg/100 g, respectively) at concentrations greater than that seen in the commercially available species of chicory and endive. Figs contained all major carotenoids appearing in plasma, albeit at low concentrations. Extra virgin cold-pressed olive oil contained substantial quantities of lutein and beta-carotene, but the more-refined 'extra light' olive oil did not.

CONCLUSIONS

These components of the traditional Mediterranean diet contribute to the higher circulating concentrations of carotenoids in Greek migrants compared to Anglo-Celtic Australians.

SPONSORSHIP

This study largely funded by the National Health and Medical Research Council of Australia (grant no. 974098). Extra virgin olive oil donated by Picuba Foods, Marrickville, NSW, Australia.

Fasting criteria for screening: test properties and agreement with glucose tolerance

The objective of this study was to characterise test properties and agreement for fasting glucose cut-offs used for screening diabetes in Indigenous Australian communities, across a range of diabetes prevalence. The oral glucose tolerance test (OGTT) was administered to adult volunteers (n=3249) for community-based diabetes screening in isolated settlements (n=25). Two-hour post-load glucose concentration was the 'gold standard' against which test properties were characterised for fasting plasma glucose cut-offs at concentrations of > or = 7.0 mmol/l (ADA criterion) and > or = 7.8 mmol/l (WHO criterion). Test sensitivity (95% CI) was greater for the ADA (72.5%, 67.4-77.1%) versus the WHO criterion (61.5%, 56.1-66.6%). Specificity was high (>98%) using either criterion. The post-test likelihood of diabetes, given a population prevalence of 14.8%, was 89.1% using the ADA criterion, and 94.9% using the WHO criterion. The ADA criterion gave better agreement than did the WHO criterion for diabetes prevalence > or = 8.6%, and the probability of false results was lower using the ADA criterion, when diabetes prevalence was > or = 12.8%. According to the ADA criterion most individuals ascribed false negative results were aged > or = 35 years, overweight/obese, or had impaired fasting glucose. The fasting glucose criterion of 7.0 mmol/l was superior to 7.8 mmol/l in screening for diabetes.

Diabetes and impaired glucose tolerance in Aboriginal Australians: prevalence and risk

The prevalence and risk of having impaired glucose tolerance (IGT) and diabetes was estimated relative to body mass index (BMI) among Australian Aboriginal people. A stratified analysis was undertaken of community screening data. Measures included fasting and 2-h glucose concentrations, and BMI (five strata: <22, 22-24.9, 25-29.9, 30-34.9 and >/=35 kg/m(2)). Age was stratified into three groups: 15-34.9, 35-44.9, and >/=45 years. Participants were men and women, ages 15-94 years (n=2626). The prevalence of IGT and diabetes, respectively, adjusted for age and BMI, was 139 and 142 cases/1000 persons among men, and 157 and 152 cases/1000 persons among women. Odds ratios (95% CI) for IGT and diabetes for increasing BMI strata >/=22 kg/m(2) ranged from 1.7 (1.0 to 2.9) to 5.1 (2.4-10.5) for IGT, and from 2.0 (1.2-3.5) to 6.1 (3.3-11.1) for diabetes. For IGT and diabetes, across genders, the population attributable risk percentages (95% CI) for BMI >/=22 kg/m(2) were 34.1% (26.2-41.9%) for IGT, and 46.4% (38.5-54.5%) for diabetes. Diabetes and IGT have reached epidemic proportions among Australian Aboriginal people. An urgent need exists for programmes to reduce the prevalence of diabetes risk factors, especially BMI of 22 kg/m(2) or more, a limit lower than advocated for Euro-American populations.

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/m(2), 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 > or = 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.

Macrovascular disease risk factors and insulin resistance in Aboriginal and Torres Strait Islander people

It has been proposed that insulin resistance (IR) underlies a cluster of cardiovascular disease (CVD) risk factors constituting a "metabolic syndrome." CVD is a leading cause of premature mortality among indigenous Australians. In a group of younger (15-44 years, fasting glucose <7.8 mmol/l) Aboriginal (n=643) and Torres Strait Islander (n=220) people participating in community-based risk factor surveys, we identified high prevalences of metabolic syndrome components: glucose intolerance, dyslipidaemia, hypertension, and IR. There were inconsistent associations of IR with other risk factors, and the data do not support a direct causal relationship between insulin and other metabolic variables. Rather, metabolic syndrome components may arise from social and environmental factors interacting with behavioural and biochemical factors in individuals.

Improvements in circulating cholesterol, antioxidants, and homocysteine after dietary intervention in an Australian Aboriginal community

BACKGROUND

Poor nutrition contributes to high rates of coronary heart disease among Australian Aboriginal populations. Since late 1993, the Aboriginal community described here has operated a healthy lifestyle program aimed at reducing the risk of chronic disease.

OBJECTIVE

We evaluated the effectiveness of a community-directed intervention program to reduce coronary heart disease risk through dietary modification.

DESIGN

Intervention processes included store management policy changes, health promotion activities, and nutrition education aimed at high-risk individuals. Dietary advice was focused on decreasing saturated fat and sugar intake and increasing fruit and vegetable intake. Evaluation of the program included conducting sequential, cross-sectional risk factor surveys at 2-y intervals; measuring fasting cholesterol, lipid-soluble antioxidants, and homocysteine concentrations; and assessing smoking status. Nutrient intakes were estimated from analysis of food turnover in the single community store.

RESULTS

There was a significant reduction in the prevalence of hypercholesterolemia (age-adjusted prevalences were 31%, 21%, and 15% at baseline, 2 y, and 4 y, respectively; P < 0.001). There were significant increases in plasma concentrations of alpha-tocopherol, lutein and zeaxanthin, cryptoxanthin, and beta-carotene across the population. Retinol and lycopene concentrations did not change significantly. Mean plasma homocysteine concentrations decreased by 3 micromol/L. There was no significant change in smoking prevalence between the 2 follow-up surveys. There was an increase in the density of fresh fruit and vegetables and carotenoids in the food supply at the community store.

CONCLUSION

This community-directed dietary intervention program reduced the prevalence of coronary heart disease risk factors related to diet.

Diabetes in Australian aboriginal and Torres Strait Islander peoples

Type 2 diabetes arises from a complex and multifactorial set of factors, including genetic susceptibility, behaviour (including diet and exercise), early nutrition, obesity and psychosocial stress, leading to insulin resistance and pancreatic failure. These factors in turn are influenced by social and physical environmental factors. Each of these may be important determinants of the high prevalence and incidence of type 2 diabetes in Australian Aboriginal and Torres Strait Islander people. Public health interventions for primary and secondary prevention need to recognize this complexity. Although a reduction in the prevalence of obesity or diabetes in the short-medium term is rarely if ever achieved, there are documented examples of community-based programs which have been effective in reducing the risk of developing type 2 diabetes and its cardiovascular complications. Such interventions need to be community-directed and appropriate to local circumstances in order to be effective.

Importance of retaining a national dietary guideline for sugar

The Australian Dietary Guidelines are currently being revised and updated. There has been public discussion about the advisability of retaining a guideline for sugar because of insufficient evidence linking sugar consumption to ill health. However, there are concerns about the quality of the self-reported food intake data on which this conclusion is based. In addition, the doubling in diabetes prevalence in Australia in the past 20 years, which is linked to increased obesity from consumption of energy-dense foods, including those with added sugars (sugar-sweetened drinks being particularly important), provides a strong rationale for retaining a dietary guideline for sugar.

Is a low fat diet the optimal way to cut energy intake over the long-term in overweight people?

Successful weight loss depends on maintaining a sustained negative energy balance. This can be achieved on diets with a normal (40% energy) fat content as well as on low fat diets. Using a 'modified fat' (MF) diet enriched with monounsaturated fat (MUFA), body weight may be lost either by calorie counting, or by allowing ad libitum food intake with careful food selection. In the latter approach high energy, high MUFA foods (predominantly olive oil, but also may include nuts and avocado) should contribute no more than 20% total energy to the diet, and other foods should be selected to minimise meal energy density. This can be achieved simply by the consumption of a wide variety of vegetables and whole grain cereal foods. It is also important to restrict foods high in saturated fat and to encourage regular exercise. Such a 'modified fat' low energy diet designed for weight loss should also contribute numerous health benefits in relation to improved metabolic control in Type 2 diabetes and reduced cardiovascular disease risk (as the diet is not only rich in MUFA but also in a range of dietary antioxidants and other bio-active phytochemicals).

Insulin resistance as a major determinant of increased coronary heart disease risk in postmenopausal women with Type 2 diabetes mellitus

AIM

To investigate the risk factors associated with clinically defined coronary heart disease (CHD) in women with Type 2 diabetes mellitus (DM).

METHODS

CHD status was assessed via standard history and resting electrocardiogram in 41 postmenopausal diabetic and 41 age- and body mass index-matched normoglycaemic women recruited from a community-based cohort. The following parameters were assessed: body composition by dual energy X-ray absorptiometry, blood pressure, metabolic and lipoprotein profile and haemostatic factors.

RESULTS

Diabetic women with CHD (n = 14) had greater insulin resistance, calculated by homeostasis model assessment (10.2 (7.0-14.8) vs. 6.5 (5.5-7.7), P = 0.010), and higher plasminogen activator inhibitor-1 (PAI-1) levels (45 (29-69) vs. 24 (19-32) ng/ml, P = 0.013), than those without CHD. They also had higher triglycerides (2.9 (2.2-3.8) vs. 2.1 (1.8-2.4) mmol/l, P = 0.016) and a trend towards reduced low-density lipoprotein particle size (25.5 +/- 0.6 vs. 25.8 +/- 0.5 nm, P = 0.097). In a logistic regression model, insulin resistance was a significant independent predictor of CHD status (odds ratio = 1.33, 95% confidence interval = 1.06-1.68, P = 0.015). In contrast, in normoglycaemic women the major risk factors for CHD were elevated cholesterol, apolipoprotein(a), apolipoprotein B and systolic blood pressure (P = 0.018, P = 0.016, P = 0.006 and P = 0.049, respectively).

CONCLUSIONS

Increased insulin resistance in association with elevated PAI-1 and dyslipidaemia appears to underpin the increased risk of CHD in women with Type 2 DM. Therapeutic approaches that increase insulin sensitivity may serve to reduce CHD risk in this vulnerable group. Diabet. Med. 18, 476-482 (2001)

Lipids and psychosocial status in aboriginal persons with and at risk for Type 2 diabetes: implications for tertiary prevention

This study assessed psychosocial correlates of dyslipidemia, towards enabling improved tertiary prevention of macrovascular complications of diabetes mellitus (DM). We tested the hypothesis that psychosocial measures are related to high-density lipoprotein cholesterol (HDL-C) and triglyceride concentrations in a rural aboriginal population in British Columbia, Canada. Persons sampled were on-reserve registered Indians (n=198) with and at risk for Type 2 DM. Relationships between HDL-C and psychosocial variables were associated with glycemic status. For persons with diabetes and impaired glucose tolerance (n=44), quality of life and mastery were positively related (P<0.001), and depression inversely related (P<0.001), to HDL-C. An apparent lack of effect of behavior suggests the influence of emotional pathways involving autonomic-neuroendocrine axes. We recommend assessing mental health, and promoting mastery and diabetes quality of life through empowerment oriented diabetes management strategies, in negotiating culturally acceptable treatment of diabetic dyslipidemia for aboriginal people.

Plasma leptin concentrations, basal metabolic rates and respiratory quotients in young and older adults

OBJECTIVE

To-examine the interrelationship of circulating leptin concentrations, basal metabolic rates (BMR) and respiratory quotients (RQ) in young and older adults.

DESIGN

Cross sectional study.

SUBJECTS

Seventy-six Australian men and women, 48 young (< 35 y) and 28 older ( > or = 50 y).

MEASUREMENTS

Fasting plasma leptin concentrations by RIA, BMR and RQ by indirect calorimetry, percentage body fat (BF%), fat mass (FM) and fat-free mass (FFM) from total body water (TBW) based on deuterium dilution, waist and hip circumferences from anthropometry.

RESULTS

Older subjects had significantly higher BF%, FM and waist-to-hip ratio (WHR), but significantly lower FFM and absolute BMR as compared to younger subjects. Absolute leptin concentrations were 60% higher in older subjects but did not achieve statistical significance. There was, however, a significant gender x age group interaction in leptin concentrations. This was reflected in a significant inverse relationship between age group and leptin in women when data was controlled for waist circumference (r = -0.38, P = 0.028), or FM (r = -0.36, P = 0.042). A similar relationship was not observed in men on controlling for BF% or FM. Log transformed plasma leptin was best explained by a model that included BF%, gender, age-group, gender x age-group and WHR r = 0.75, adjusted r2 = 0.56, standard error of estimate (SEE) = 0.73 ng/ml). BMR was best explained by FFM, FM and age group r = 0.94, adjusted r2 = 0.87; SEE = 429 kJ/day). On controlling for BF%, WHR and FFM, leptin was negatively related to RQ only in older men (r = -0.67, P = 0.033). There was no relationship of leptin to BMR in the groups studied.

CONCLUSION

The study demonstrates an age-related modification of the gender bias in leptin, and a gender-specific inverse relationship between leptin and RQ in older people. The decline in leptin and the lack of a relationship between RQ and leptin in older women may indicate an increased risk of weight gain relative to older men.

Albuminuria in Australian Aboriginal people: prevalence and associations with components of the metabolic syndrome

AIMS/HYPOTHESIS

To examine the prevalence and associations with the metabolic syndrome of albuminuria among Australian Aboriginal people.

METHODS

Early-morning urine specimens were collected as part of community-based risk factor surveys assessing the prevalence of diabetes and cardiovascular disease in eight remote communities, with a sample size of 1,075 people. Microalbuminuria was defined as urinary albumin : creatinine ratio 3.4-33.9 mg/mmol, macroalbuminuria as albumin: creatinine ratio equal to or greater than 34 mg/mmol.

RESULTS

There were high prevalences of microalbuminuria (men 22.2 %, women 26.9 %) and of macroalbuminuria (men 10.4%, women 13.5%). There were highly statistically significant linear associations of microalbuminuria and macroalbuminuria with increasing number of coexisting components of the metabolic syndrome (hypertension, glucose intolerance, dyslipidaemia, insulin resistance, abdominal obesity): among people with zero, one, two and three to five of these conditions, respectively, prevalence of microalbuminuria was 16%, 20%, 36% and 32% (p < 0.001); prevalence of macroalbuminuria was 2%, 6%, 12% and 32% (p < 0.001). There were independent associations of microalbuminuria with hypertension (odds ratio, 95% confidence interval = 2.36, 1.63-3.42) and diabetes (2.10, 1.28-3.45): macroalbuminuria was independently associated with hypertension (6.39, 3.93-10.4), diabetes (3.49, 1.93-6.28) and abdominal obesity (4.56, 2.40-8.64) and had a weaker association with insulin resistance (1.99, 1.12-3.54). Dyslipidaemia and impaired glucose tolerance were neither independently associated with microalbuminuria or macroalbuminuria, nor was insulin resistance or abdominal obesity independently associated with microalbuminuria.

CONCLUSION/INTERPRETATION

There was a strong clustering of albuminuria with components of the metabolic syndrome. Diabetes, hypertension and abdominal obesity are major contributors to high rates of albuminuria among Australian Aboriginal people.

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 (FFM(DD)), SFT using the equations of Durnin and Womersley (Br J Nutr 1974; 32: 77-97) (FFM(SFT)), and BIA using the equations of Lukaski et al (J Appl Physiol 1986; 60: 1327-1332) (FFM(Lu)), Segal et al (Am J Clin Nutr 1988; 47: 7-14) (FFM(Se)) and Heitmann (Eur J Clin Nutr 1990; 44: 831-837) (FFM(He)). 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 FFM(SFT) 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 FFM(DD) was possible from the combination of FFM(He), 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 Heitmann's 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, Heitmann's 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.

Arabinoxylan fiber from a by-product of wheat flour processing behaves physiologically like a soluble, fermentable fiber in the large bowel of rats

Arabinoxylan is a major dietary fiber component of many cereals. Its physiological effects in the colon are largely unknown. This study examined the effects of an arabinoxylan-rich fiber (AX) extracted from a by-product of wheat flour processing in the rat colon compared with well-characterized soluble/rapidly fermentable and insoluble/slowly fermentable fibers. Rats were fed diets containing no fiber (NF) or 100 g/kg of total dietary fiber from AX, guar gum (GG) or wheat bran (WB) for 4 wk. Cecal mass and short-chain fatty acid (SCFA) pool were significantly higher while pH was significantly lower in the fiber-supplemented groups, particularly in the AX and GG groups. The pattern of SCFA production in the cecum was altered; AX fiber was a good source for acetate while GG and WB favored propionate and butyrate production, respectively. Fecal output was 7-, 6- and 5-fold higher, respectively, in the AX, GG and WB than in the NF groups (P < 0.01). All epithelial proliferation indices (crypt column height, number of mitotic cells/crypt column and mitotic index) differed significantly across the groups in a descending order of AX > GG > WB > NF. Distal mucosal dipeptidyl peptidase IV activities, which indicate cell differentiation status, were significantly lower in fiber-supplemented groups than in the NF groups. Distal mucosal alkaline phosphatase activities, induced as a response to injury or stress, were significantly higher for the AX and GG groups than for the NF or WB groups (P < 0.001). These results indicate that AX fiber behaves like a rapidly fermentable, soluble fiber in the rat colon.

Reduced prevalence of impaired glucose tolerance and no change in prevalence of diabetes despite increasing BMI among Aboriginal people from a group of remote homeland communities

OBJECTIVE

To examine trends in glucose tolerance and coronary risk among Aboriginal people from a group of homeland communities in central Australia during a 7-year follow-up period.

RESEARCH DESIGN AND METHODS

Community-based screenings of adult volunteers were performed in 1988 (n = 437; 93% response rate) and in 1995 (n = 424; 85% response rate). A health promotion intervention program commenced after the 1988 survey that focused on the benefits of exercise and appropriate diet.

RESULTS

Mean (95% CI) BMI increased significantly from 22.8 kg/m2 (22.3-23.2) to 24.2 kg/m2 (23.8-24.7) during the follow-up period (P < 0.001). This increase was similar for men and women and across all age-groups. The increase in BMI was greater among subjects residing adjacent to a store compared with those residing in communities located far from a store (P < 0.001). Decreases were evident in the prevalence of impaired glucose tolerance (IGT) (from 22.5 to 10.1% among women, P < 0.001; from 12.2 to 6.5% among men, P = 0.074) and hypercholesterolemia (from 36.7 to 25.8% among women, P < 0.01; from 52.4 to 44.0% among men, P = 0.147), but no change was evident in the prevalence of diabetes. Smoking remained rare among women (<4%) and decreased among men (from 52.9 to 40.8%, P < 0.05).

CONCLUSIONS

The trends in glucose intolerance were clearly better than have been observed in other Aboriginal communities. The institution of an intervention program corresponded with reductions in the prevalence of IGT, hypercholesterolemia, and smoking. The prevalence of diabetes remained unaltered despite a significant increase in mean BMI, possibly because of the promotion of increased physical activity levels.

Increase in prevalence of obesity and diabetes and decrease in plasma cholesterol in a central Australian aboriginal community

OBJECTIVE

To document change in prevalence of obesity, diabetes and other cardiovascular disease (CVD) risk factors, and trends in dietary macronutrient intake, over an eight-year period in a rural Aboriginal community in central Australia.

DESIGN

Sequential cross-sectional community surveys in 1987, 1991 and 1995.

SUBJECTS

All adults (15 years and over) in the community were invited to participate. In 1987, 1991 and 1995, 335 (87% of eligible adults), 331 (76%) and 304 (68%), respectively, were surveyed.

MAIN OUTCOME MEASURES

Body mass index and waist: hip ratio; blood glucose level and glucose tolerance; fasting total and high density lipoprotein (HDL) cholesterol and triglyceride levels; and apparent dietary intake (estimated by the store turnover method).

INTERVENTION

A community-based nutrition awareness and healthy lifestyle program, 1988-1990.

RESULTS

At the eight-year follow-up, the odds ratios (95% CIs) for CVD risk factors relative to baseline were obesity, 1.84 (1.28-2.66); diabetes, 1.83 (1.11-3.03); hypercholesterolaemia, 0.29 (0.20-0.42); and dyslipidemia (high triglyceride plus low HDL cholesterol level), 4.54 (2.84-7.29). In younger women (15-24 years), there was a trembling in obesity prevalence and a four- to fivefold increase in diabetes prevalence. Store turnover data suggested a relative reduction in the consumption of refined carbohydrates and saturated fats.

CONCLUSIONS

Interventions targeting nutritional factors alone are unlikely to greatly alter trends towards increasing prevalences of obesity and diabetes. In communities where healthy food choices are limited, the role of regular physical activity in improving metabolic fitness may also need to be emphasised.

Arabinoxylan fiber, a byproduct of wheat flour processing, reduces the postprandial glucose response in normoglycemic subjects

BACKGROUND

Arabinoxylan (AX) is the major component of dietary fiber in the cereal grains that make up a large proportion of our diet. However, the physiologic effect of AX is unknown.

OBJECTIVE

The objective of this study was to determine whether AX improves postprandial glucose and insulin responses in healthy humans.

DESIGN

AX-rich fiber was extracted from the byproduct of wheat-flour processing. Three isoenergic breakfasts, comprising bread, margarine, and jam, had 75 g available carbohydrate, 10 g protein, and 14 g fat and contained 0, 6, and 12 g AX-rich fiber, respectively. Fourteen healthy subjects consumed the 3 breakfast meals in random order on 3 mornings >/=3 d apart after an overnight fast. Blood was taken from the subjects at regular intervals over 2 h and was analyzed for glucose and insulin. The palatability of bread containing AX-rich fiber was compared with that of a control bread.

RESULTS

Compared with the control meal containing 0 g AX-rich fiber, the peak postprandial glucose concentration after meals containing 6 and 12 g AX-rich fiber was significantly lower (6. 3 +/- 1.3 compared with 7.2 +/- 1.0 mmol/L, P < 0.01; 5.9 +/- 0.9 compared with 7.2 +/- 1.0 mmol/L, P < 0.001, respectively). The incremental area under the curve (IAUC) for glucose was 20.2% (95% CI: 5.8%, 34.7%; P < 0.01) and 41.4% (25.9%, 56.8%; P < 0.001) lower, whereas IAUC for insulin was 17.0% (2.0%, 32.1%; P < 0.05) and 32. 7% (18.8%, 46.6%; P < 0.001) lower, respectively. Bread containing AX-rich fiber was as pala as 50% whole-wheat bread when evaluated with sensory analysis by 30 volunteers.

CONCLUSIONS

Postprandial glucose and insulin responses were improved by ingestion of AX-rich fiber. Further research is required to determine whether AX-rich fiber is of benefit to people with type 2 diabetes.

Effectiveness of a community-directed 'healthy lifestyle' program in a remote Australian aboriginal community

OBJECTIVE

To assess the sustainability and effectiveness of a community-directed program for primary and secondary prevention of obesity, diabetes and cardiovascular disease in an Aboriginal community in north-west Western Australia.

METHOD

Evaluation of health outcomes (body mass index, glucose tolerance, and plasma insulin and triglyceride concentrations) in a cohort of high-risk individuals (n = 49, followed over two years) and cross-sectional community samples (n = 200 at baseline, 185 at two-year and 132 at four-year follow-ups), process (interventions and their implementation) and impact (diet and exercise behaviour).

RESULTS

For the high-risk cohort, involvement in diet and/or exercise strategies was associated with protection from increases in plasma glucose and triglycerides seen in a comparison group; however, sustained weight loss was not achieved. At the community level, significant reductions were observed in fasting insulin concentration but no change in prevalence of diabetes, overweight or obesity. Weight gain remained a problem among younger people. Sustainable improvements were observed for dietary intake and level of physical activity. These changes were related to supportive policies implemented by the community council and store management.

CONCLUSIONS

Community control and ownership enabled embedding and sustainability of program, in association with social environmental policy changes and long-term improvements in important risk factors for chronic disease.

IMPLICATIONS

Developmental initiatives facilitating planning, implementation and ownership of interventions by community members and organisations can be a feasible and effective way to achieve sustainable improvements in health behaviours and selected health outcomes among Aboriginal people.

Diabetes incidence in an Australian aboriginal population. An 8-year follow-up study

OBJECTIVE

To examine prospectively the association between age, BMI, and subsequent incidence of type 2 diabetes in Australian aboriginal people.

RESEARCH DESIGN AND METHODS

We performed a stratified analysis of incidence data from a community-based longitudinal study. Measures included fasting and 2-h postload glucose concentrations, and BMI, stratified into four categories. Subjects were 882 male and female participants in diabetes screening initiatives in two remote Australian aboriginal communities, free from diabetes at baseline, ages 15-77 years.

RESULTS

There were 46 incident cases of diabetes over 2,808 person-years of follow-up. BMI modified strongly the sex- and community-adjusted association between age and diabetes incidence (P < 0.001). Adjusted for age, sex, and community, the population diabetes incidence rate was 20.3 cases/1,000 person-years, with BMI-specific rates of 10.7-47.2 cases/1,000 person-years, and relative risks (95% CI) for BMI strata beyond the reference category (< 25 kg/m2) of 3.3 (1.5-7.0), 2.7 (1.1-6.8), and 4.4 (1.7-11.6), respectively. The population's attributable risk (95% CI) associated with BMI beyond the reference category was 70.1% (58.1-82.4).

CONCLUSIONS

BMI-specific diabetes incidence rates in Australian aboriginal people are among the highest in the world. Diabetes incidence in the lowest BMI category (10.7 cases/1,000 person-years) is two to five times greater than corresponding rates for non-aboriginal populations. An urgent need exists to prevent weight gain associated with diabetes. Further study is required to determine for aboriginal people an optimal range of BMI, likely lower than that suggested for non-aboriginal populations.

Glycated hemoglobin as an indicator of social environmental stress among indigenous versus westernized populations

BACKGROUND

This study assessed whether glycated hemoglobin concentration, an indicator of psychogenic stress, differs between indigenous populations and non-indigenous reference groups.

METHODS

Multivariate and stratified analyses were undertaken of cross-sectional data from multi-center community-based diabetes diagnostic and risk factor screening initiatives in Canada and Australia. Population groups were Australian Aborigines (n = 116), Torres Strait Islanders (n = 156), Native Canadians (n = 155), Greek migrants to Australia (n = 117), and Caucasian Australians (n = 67). Measurements included fasting glycated hemoglobin (HbA(1c)) concentration, fasting and 2-h post-load glucose concentrations, body mass index, waist-to-hip ratio, and demographic variables.

RESULTS

Mean HbA(1c) concentrations were greater for indigenous groups than for Greek migrants and Caucasian Australians (P < 0. 0001). The covariate adjusted indigenous versus non-indigenous difference (95% CI) was 0.90 (0.58-1.22) percentage units, 18.2% higher for indigenous people. Stratified analyses indicated greater HbA(1c) for indigenous than for non-indigenous persons with normoglycemia (P = 0.009), impaired glucose tolerance (P = 0.097), and diabetes (P < 0.0001).

CONCLUSIONS

HbA(1c) concentrations are greater for indigenous than for non-indigenous groups. Social changes, low control, and living conditions associated with westernization may be inherently stressful at the biological level for indigenous populations in westernized countries.

Dietary composition affects regional body fat distribution and levels of dehydroepiandrosterone sulphate (DHEAS) in post-menopausal women with Type 2 diabetes

OBJECTIVE

To compare effects of a high carbohydrate (high-CHO) and a monounsaturated fat diet (high-MUFA) on body fat distribution and sex hormones in post-menopausal women with Type 2 diabetes.

DESIGN

Randomised cross-over with no washout.

SETTING

Geelong Hospital outpatient.

SUBJECTS

Thirty four women were recruited, 30 completed the study, and data are presented for 21 women compliant to the high-CHO diet.

INTERVENTIONS

Women followed a high-CHO diet (20% energy (%E) from fat, 60%E from carbohydrate and a high-MUFA diet (40%E from fat, half as monounsaturated fat, 40%E from carbohydrate) in random order for 12 weeks each.

MAIN OUTCOME MEASURES

Dietary compliance was measured by change in linoleic acid (C18:2,omega-6) in plasma cholesteryl esters. Body composition was measured by dual-energy X-ray absorptiometry. Fasting concentrations of glucose and insulin were measured in plasma. Steroid hormones and sex hormone binding globulin (SHBG) were measured in serum.

RESULTS

On the high-CHO diet C18:2,omega-6 in plasma cholesteryl esters declined by 5.4% (95% confidence intervals (CI), -2.5% to -8.4%, P=0.0015). Fat was lost mainly from the lower body (lower body loss -0.71 kg, 95%CI, -0.43 to -1.00 kg, P=0.001; upper body loss -0.15 kg, 95%CI, -0.76 to +0.46 kg, P=0.6). Yet on the high-MUFA diet, lower body fat loss was minimal (-0.22 kg, 95%CI, +0.11 to -0.55 kg, P = 0.2). By general linear modelling (GLM), differences in lower body fat loss were significantly related to diet (P = 0.04). After adjustment for age, dehydroepiandrosterone sulphate (DHEAS) concentrations after the high-CHO diet were related to levels of lower body fat (r = 0.394, P = 0.04).

CONCLUSIONS

In women with Type 2 diabetes following a high-CHO diet for 12 weeks the disproportionate loss of lower body fat is related to a decline in DHEAS.

Stability of individual carotenoids, retinol and tocopherols in human plasma during exposure to light and after extraction

We have modified gradient HPLC procedures for simultaneous quantification of retinol, gamma-tocopherol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, trans-lycopene, cis-lycopene, alpha-carotene and beta-carotene in 200-microl aliquots of human plasma. The photosensitivity of these analytes in plasma exposed to fluorescent lighting for up to 72 h was investigated and most were stable under these conditions. The stability of these analytes held in darkness at -20 degrees C, 4 degrees C or room temperature for up to 48 h after extraction from plasma was also investigated. Variability in measurement of most analytes was greater at room temperature than at 4 degrees C or -20 degrees C. There were statistically significant variations in the measured concentrations of some analytes in samples kept cold. However, the magnitude of these variations was small and of little biological significance, particularly over the first 24 h.

The prevalence of pressure damage in acute care hospital patients in the UK

This paper aims to provide information on the prevalence of pressure damage in UK hospital patients since 1992. A survey method and data handling service provided by a medical device company was used to set targets and monitor trends. The results of these surveys provide evidence that over a six year period, the prevalence of pressure damage in this population in the UK has shown a significant reduction.

Effects of regular walking on cardiovascular risk factors and body composition in normoglycemic women and women with type 2 diabetes

OBJECTIVE

To examine the impact of a 12-week walking program on body composition and risk factors for cardiovascular disease in women with type 2 diabetes and in normoglycemic women with first-degree diabetic relatives.

RESEARCH DESIGN AND METHODS

There were 11 postmenopausal women with type 2 diabetes and 20 normoglycemic women of similar age and BMI who were asked to walk 1 h per day on 5 days each week for 12 weeks. Fitness (estimated VO2max) was assessed with a 1.6-km walking test; body composition was measured by dual-energy X-ray absorptiometry; and sex hormone, metabolic, and lipid concentrations were measured in serum.

RESULTS

After 12 weeks, estimated VO2max improved in both groups (P < 0.005). In the diabetic women, BMI and fat content of the upper body and android waist region decreased (P < 0.05). Concentrations of fasting blood glucose (P < 0.05) HbAlc (P < 0.05), total cholesterol (P < 0.005), and LDL cholesterol (P < 0.05) decreased, while HDL cholesterol and sex hormones were unchanged. In contrast, normoglycemic women failed to lose body fat after 12 weeks of exercise in a walking program. However, their HbAlc, total cholesterol, LDL cholesterol, sex hormone-binding globulin, and total testosterone concentrations decreased (P < 0.05). On pooling the data and including diabetes as a categorical grouping variable, stepwise multiple regression analysis indicated that the change in centralized body fat, but not the change in VO2max, was related to change in fasting blood glucose.

CONCLUSIONS

Twelve weeks of walking increased the fitness of diabetic and normoglycemic women. Improvement of fasting blood glucose was related to the loss of centralized body fat rather than to improved fitness.

Is there evidence for an age-related reduction in metabolic rate?

To determine whether the age-related reduction in basal metabolic rate (BMR) is explained by a quantitative and/or qualitative change in the components of lean tissue, we conducted a cross-sectional study in groups of young (n = 38, 18-35 yr) and older (n = 24, 50-77 yr) healthy individuals. BMR was measured by indirect calorimetry. Body composition was obtained by using dual-energy X-ray absorptiometry (DEXA), which permitted four compartments to be quantified [bone mineral mass, fat mass (FM), appendicular lean tissue mass (ALTM), and nonappendicular lean tissue mass (NALTM)]. Absolute BMR and ALTM were lower, whereas FM was significantly higher in the older, compared with young, subjects. BMR, adjusted for differences in FM, ALTM, and NALTM, was significantly lower in the older subjects by 644 kJ/day. In separate regression analyses of BMR on body compartments, older subjects had significantly lower regression coefficients for ALTM and NALTM, compared with young subjects. Hence, the age-related decline in BMR is partly explained by a reduction in the quantity, as well as the metabolic activity, of DEXA-derived lean tissue components.

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.

METHODS

Baseline survey of 826 Aboriginal adults in rural central Australian communities in 1987-88 with a follow-up survey of 416 (56% response rate, excluding deaths). Each time, they had a 75 g oral glucose tolerance test (OGTT), and blood pressure and anthropometry measurement. Deaths and hospitalisations for all of the original cohort were recorded for the seven-year period.

RESULTS

Homelands residents had a lower baseline prevalence of diabetes (risk ratio [RR] = 0.77, 0.59-1.00), hypertension (RR = 0.66, 0.54-0.80) and overweight/obesity (RR = 0.70, 0.59-0.83). The incidence of diabetes was lower among homelands residents (RR = 0.70, 0.46-1.06). They were less likely to die than those living in centralised communities (RR = 0.56, 0.37-0.85) and less likely to be hospitalised for any cause (RR = 0.79, 0.71-0.87), particularly infections (RR = 0.70, 0.61-0.80), injury involving alcohol (RR = 0.61, 0.47-0.79) and other injury (RR = 0.75, 0.60-0.93). Mean age at death was 58 and 48 years for residents of homelands and centralised communities respectively.

CONCLUSION

Aboriginal people who live in homelands communities appear to have more favourable health outcomes with respect to mortality, hospitalisation, hypertension, diabetes and injury, than those living in more centralised settlements in Central Australia. These effects are most marked among younger adults.

Modulation of fecal markers relevant to colon cancer risk: a high-starch Chinese diet did not generate expected beneficial changes relative to a Western-type diet

In a randomized, crossover dietary intervention study, 12 Australians (of white descent) consumed a diet typical of low-income communities in China and an average Australian diet so that effects on fecal markers thought to be relevant to colon cancer risk could be compared. The Chinese diet contained 35.3 g starch/MJ daily [including 2 g resistant starch (RS)/MJ and 1.5 g nonstarch polysaccharides (NSPs)/MJ]; the Australian diet contained 12 g starch/MJ daily (including 0.8 g RS and 2.7 g NSPs/MJ). Subjects followed each diet for 3 wk. Serum cholesterol concentrations were significantly lower after the low-fat, high-starch Chinese diet than after the Australian diet (mean +/- SEM: 4.17 +/- 0.30 compared with 5.04 +/- 0.28 mmol/L, respectively, P < 0.05), a difference indicative of dietary compliance. Fecal pH was lower after the Chinese diet (6.51 +/- 0.04) than after the Australian diet (6.63 +/- 0.05; P < 0.05). For all other fecal markers examined, however, the Chinese diet produced less favorable changes, including lower fecal bulk (86 +/- 11 compared with 141 +/- 20 g wet wt/d, P < 0.01), slower transit through the gut (69 +/- 6 compared with 56 +/- 7 h, P = 0.06), lower fecal concentrations of short-chain fatty acids [72.8 +/- 7.3 compared with 98 +/- 7.6 mmol/L (including butyrate: 12.2 +/- 1.3 compared with 18.4 +/- 2.3 mmol/L), P < 0.05], and higher fecal concentrations of potentially damaging ammonia (540 +/- 50 compared with 450 +/- 40 mg/L, P < 0.01) and phenols (109.2 +/- 13.2 compared with 68.5 +/- 12.9 mg/L, P < 0.01). These results suggest that consumption of a high-starch diet alone is insufficient to reduce the risk of developing colon cancer.

Do postmenopausal women with NIDDM have a reduced capacity to deposit and conserve lower-body fat?

OBJECTIVE

To compare regional body fat distribution and sex hormone status of postmenopausal women with NIDDM with those of age- and BMI-matched normoglycemic women.

RESEARCH DESIGN AND METHODS

The regional body fat distribution and sex hormone status of 42 postmenopausal women with NIDDM were compared with those of 42 normoglycemic women matched for age and BMI, who served as control subjects. Body composition was measured by dual-energy X-ray absorptiometry, and sex hormone-binding globulin (SHBG) and testosterone were measured in serum.

RESULTS

Although the levels of total body fat were similar between the two groups, the women with NIDDM had significantly less lower-body fat (LBF) (P < 0.01) than the control subjects matched for age and BMI. This pattern of fat deposition in women with NIDDM was accompanied by an androgenic hormone profile, with decreased SHBG concentration and an increased free androgen index (P < 0.05 and P < 0.01, respectively).

CONCLUSIONS

A reduced capacity to deposit and/or conserve LBF may be an independent factor associated with (or may be a marker of) the metabolic manifestations of the insulin resistance syndrome in women with NIDDM. The possibility that the smaller relative accumulation of LBF is a consequence of the androgenic hormonal profile should be investigated in future studies.

No evidence for an ethnic influence on basal metabolism: an examination of data from India and Australia

A lower BMR of Indians, when compared with Westerners matched for age, sex and either surface area or body weight, has often been reported in the literature and has been interpreted to reflect an ethnic influence on BMR. To determine the contribution of body composition to these observed differences in BMR, we analysed the data on ninety-six Indians and eighty-one Caucasian Australians of both sexes, aged 18-30 years, studied in Bangalore, India and Melbourne, Australia. Absolute BMR and BMR adjusted for body weight were significantly lower in Indians when compared with Australians of the corresponding sex. However, BMR adjusted for fat-free mass (FFM) in men, and BMR adjusted for FFM and fat mass (FM) in women, were not significantly different between the two groups. Stepwise regression of FFM, FM, sex (0 = women; 1 = men) and ethnicity (0 = Indian; 1 = Australian) on BMR, resulted in the following relationship for the combined data on all subjects: BMR = 88.7 x FFM (kg) + 1713 (n 177; r 0.92; r2 0.85; SEE 425 kJ). The Indian equations of Hayter & Henry (1994), based on body weight, resulted in a significant bias (measured-predicted BMR) of 318 (SE 54) kJ/d in Indian men and -409 (SE 70) kJ/d in Indian women. The equation of Cunningham (1991), based on FFM, accurately predicted the BMR of Indian men, Indian women and Australian men. The small but significant bias of 185 (SE 61) kJ/d in Australian women, may be explained by the significant contribution of FM to BMR in this group. The present study does not provide any evidence for an ethnic influence on basal metabolism. The results strongly support the use of FFM, rather than body weight, for the prediction of BMR in population groups of varying body size and composition. This would allow an accurate estimation of BMR and hence energy requirements in population groups worldwide.

The influence of a breakfast meal on the assessment of body composition using bioelectrical impedance

OBJECTIVE

To investigate the effect of a breakfast meal on bioelectrical impedance (BI).

DESIGN

Three separate interventions.

SETTING

A university based study.

SUBJECTS

Young, healthy volunteers recruited from staff. Twenty-nine subjects (11 men, 18 women), ten subjects (two men and eight women) and 13 subjects (2 men and 11 women) completed the first, second and third protocol, respectively.

INTERVENTIONS

Total body BI (protocol 1) or both total body BI and segmental BI (namely arm, leg or torso BI); (protocol 3) was measured in the fasting state and for up to 5 h after the consumption of a breakfast meal containing 28% energy from fat. In the second protocol, total body BI was measured in the same way on two occasions after subjects consumed isocaloric meals containing either 28% energy or 4% energy from fat.

RESULTS

Consumption of a 2300 kJ meal was followed by a significant (P = 0.0002) decrease in BI (95% confidence intervals 12.5 and 35.3), a change which occurred 2 h after the meal and continued until 5 h, irrespective of meal fat content. The fall in total body BI was accounted for primarily by a fall in the BI of the limbs, with virtually no contribution from the torso.

CONCLUSION

To ensure consistency in the interpretation of BI for body composition analysis, it is important that measurements are made in the fasting state.

Are there ethnic differences in the association between body weight and resistance, measured by bioelectrical impedance?

OBJECTIVE

To describe ethnic differences in the relationship between body size and body composition. Knowledge about such differences is important when studying obesity-related complications, such as hypertension and non-insulin dependent diabetes, because it may not be possible to generalize results from one study population to other populations.

DESIGN

Cross-sectional study.

SUBJECTS

Four groups of different ethnic identity (2987 Caucasians (Danes), 243 predominantly Melanesian (Torres Strait Islanders from northern Australia), 206 Australian Aborigines and 146 Polynesians (New Zealand Samoans), aged 30-70 y, were studied.

MEASUREMENTS

We examined associations between body weight and bioelectrical impedance, as a measure of body composition.

RESULTS

Except for Australian Aborigines, associations (slopes) between body weight and resistance were generally constant in the different ethnic groups, once height and age differences had been considered, indicating that this relationship may involve a certain universality, that is independent of the population specificity for impedance measurement. Systematic differences in instrument readings or electrodes did not seem to be responsible for the differences found.

CONCLUSION

With the exception of Australian Aborigines, there may be a constant relation between body size and body composition (total body water or fat free mass) of different ethnic groups, that depends on gender and age category only.

Insulin resistance syndrome in Australian aboriginal people

1. Like many indigenous populations, Australian Aboriginal people have developed high rates of obesity, non-insulin-dependent diabetes mellitus (NIDDM) and cardiovascular and renal disease following the transition from a traditional to an 'urbanized' lifestyle. These conditions tend to cluster as part of the insulin resistance syndrome. 2. The prevalence of overweight people and obesity in Australian Aboriginal populations ranges from 0% in communities with a traditionally orientated lifestyle to well over 50% in the worst affected communities. There is a predominantly central pattern of fat deposition in both men and women, which is associated with greater insulin resistance and cardiovascular risk than is peripheral fat deposition. 3. Data from four previously published, population-based surveys in Aboriginal communities were combined to give a cohort of 1079 subjects of 15 years and older. Several conditions of the insulin resistance syndrome had a strong, positive association with increasing body mass index (BMI): NIDDM (both cross-sectionally and longitudinally), hypertension, dyslipidaemia and albuminuria. Remaining lean (BMI < 20 kg/m2) protected even older Aboriginal people from these conditions to a large extent. 4. Community based programmes to increase physical activity and improve dietary quality are likely to be the major means by which conditions associated with insulin resistance can be prevented in Aboriginal populations.

Amino acid levels following beef protein and amino acid supplement in male subjects

In the present study the plasma amino acid response of six lean subjects to a protein meal and a commercial amino acid supplement were compared. The amino acid supplement studied was formulated and marketed to be taken after exercise and at other times with the aim of increasing protein synthesis and/or decreasing protein degradation and to lower the ratio of tryptophan to the other large neutral amino acids (LNAA); tyrosine, valine, leucine, isoleucine, phenylalanine and methionine (trp/LNAA), to reduce fatigue. The amino acid supplement administered at the dose recommended by the manufacturer (4 g) was able to bring about a rapid but short-lived (15-30 min) increase in plasma amino acid concentrations and to produce a similarly brief decrease in the trp/LNAA and tyr/LNAA ratios and therefore achieved these aims with respect to amino acid levels even if only briefly. The changes in trp/LNAA and tyr/LNAA ratios after the supplement were of the same order as those produced after the much larger (50 g) protein meal but of shorter duration. However the relatively small insulin response after the amino acid supplement points to a lower level of amino acid uptake by muscle and other tissues for protein synthesis compared to that produced by the beef meal.

Community-based approaches for the primary prevention of non-insulin-dependent diabetes mellitus

The prevalence of non-insulin-dependent (Type 2) diabetes mellitus (NIDDM) is increasing worldwide. Although recent studies suggest that primary prevention of NIDDM is possible, strategies for controlling the NIDDM pandemic remain under development. Successful interventions to date have mainly relied upon the control of obesity and increased exercise, although pharmacological agents are being studied. While a mixture of both high risk and population-based approaches is likely to be required, the former will not prevent new high risk cases developing. Unfortunately, the success in the primary prevention of cardiovascular disease through risk factor reduction has not controlled obesity, the most important risk factor for NIDDM. New strategies are currently being developed and focus upon changes in the food supply of whole populations and a community development approach to altering attitudes to food and exercise. As these interventions are in the early stages of their development, formative, process, and quantitative evaluation remain essential components of any community-based programme aimed at the primary prevention of NIDDM.

The effect of oral contraceptive agents on the basal metabolic rate of young women

The use of oral contraceptive agents by women may be a factor that contributes to the observed inter-individual variability in the BMR. We, therefore, measured the BMR, body build and composition in two groups of young women and also assessed their self-reported level of physical activity. One group had been using oral contraceptive agents for a period of 6 months or more (OCA, n 24), while the other group had never used oral contraceptives (NOCA, n 22). There were no significant differences in age, body build or composition. The absolute BMR in the groups were not significantly different when compared using an unpaired t test (OCA: 5841 (SD 471) v. NOCA: 5633 (SD 615) kJ/d). However, using an analysis of covariance, with either body weight or a combination of fat and fat free mass as covariates, the OCA group had a BMR almost 5% higher than that of the NOCA group (OCA: 5871 v. NOCA: 5601 kJ/d; P = 0.002). When those subjects with high self-reported levels of physical activity were excluded, the difference in BMR between the two groups persisted (P = 0.001). An ANOVA of oral contraceptives use and phase of menstrual cycle showed significant differences in BMR with use of oral contraceptives (P = 0.004) but no difference in BMR between phases of the menstrual cycle. In conclusion, the use of oral contraceptive agents deserves consideration when conducting and analysing data from studies on energy metabolism in young women, as it results in a significantly higher BMR.

The validity of predicting the basal metabolic rate of young Australian men and women

OBJECTIVES

To assess the accuracy of the Schofield, Schofield & James (1985) equations and those of Hayter & Henry (1994) for the prediction of the basal metabolic rate (BMR), of young Australians.

DESIGN

BMR was measured by indirect calorimetry, while fat free mass (FFM) and fat mass (FM) were measured by bioelectric impendence analysis (BIA) in 128 volunteers (39 men and 89 women), aged between 18 and 30 y.

SETTING

Deakin Institute of Human Nutrition, Deakin University, Melbourne, Australia.

RESULTS

The measured BMR of Australian men and women were significantly lower (P < or = 0.001) than the predicted BMR using the Schofield et al (1985) equation, with a mean (s.d.) bias (bias = measured - predicted BMR) of -406(513) kj/d in men and -124(348) kj/d in women. The measured BMR of Australian men and women were similar to the predicted BMR using the equations of Hayter & Henry (1994) and bias was unrelated to body weight. BMR adjusted for FFM and FM was significantly higher by three percent in women on oral contraceptive agents (OCA) as compared to those not on OCA.

CONCLUSIONS

The Schofield et al (1985) equations are not valid for the prediction of BMR of young Australian men and women. The equations of Hayter & Henry (1994) for North Europeans and Americans, provide an accurate estimate of the BMR of Australian men and women at the group level. However, in young women not using OCA a correction factor of 0.97 applied to the predicted BMR provides a better estimate.

A low-fat diet supplemented with monounsaturated fat results in less HDL-C lowering than a very-low-fat diet

OBJECTIVE

The purpose of this study was to compare the effects of a very-low-fat diet with a low-fat diet supplemented with monounsaturated oil on plasma lipid levels in subjects with hypercholesterolemia.

DESIGN

The 8-week study was divided into one 2-week baseline diet and two 3-week intervention periods in a randomized crossover design.

SETTING

The study was conducted in an outpatient setting at the Deakin Institute of Human Nutrition, Deakin University, Geelong, Australia.

SUBJECTS

Twenty-four free-living subjects with hypercholesterolemia participated in and completed the study.

INTERVENTION

After a 2-week baseline period of a self-selected diet, subjects were assigned to one of two dietary interventions: a very-low-fat (10% of energy from fat), high-carbohydrate diet or a low-fat (26% of energy from fat) diet supplemented with olive oil and an olive oil-based margarine.

MAIN OUTCOME MEASURES

Lipid measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations. Plasma cholesteryl esters were measured to monitor compliance.

STATISTICAL ANALYSES

A paired t test was used to assess differences between treatment periods for each subject. The dependence of the difference between treatment periods on the covariates of age, sex, initial cholesterol concentration, and energy intake was analyzed using repeated measures and analysis of covariance.

RESULTS

The low-fat diet supplemented with monounsaturated fat resulted in significantly less high-density lipoprotein cholesterol lowering than the very-low-fat diet (P=.005). Both interventions resulted in significant reductions in both low-density lipoprotein cholesterol and total cholesterol compared with the baseline diet.

APPLICATIONS

This study suggests that a low-fat diet enriched with olive oil provides advantages over a very-low-fat diet in the control of serum lipoproteins among persons with hypercholesterolemia.