Jane E O'Shea

Cereal grains, legumes, and weight management: a comprehensive review of the scientific evidence

There is strong evidence that a diet high in whole grains is associated with lower body mass index, smaller waist circumference, and reduced risk of being overweight; that a diet high in whole grains and legumes can help reduce weight gain; and that significant weight loss is achievable with energy-controlled diets that are high in cereals and legumes. There is weak evidence that high intakes of refined grains may cause small increases in waist circumference in women. There is no evidence that low-carbohydrate diets that restrict cereal intakes offer long-term advantages for sustained weight loss. There is insufficient evidence to make clear conclusions about the protective effect of legumes on weight.

Effect of 6 weeks' consumption of β-glucan-rich oat products on cholesterol levels in mildly hypercholesterolaemic overweight adults

Several regulatory bodies have approved a health claim on the cholesterol-lowering effects of oat β-glucan at levels of 3·0 g/d. The present study aimed to test whether 1·5 g/d β-glucan provided as ready-to-eat oat flakes was as effective in lowering cholesterol as 3·0 g/d from oats porridge. A 6-week randomised controlled trial was conducted in eighty-seven mildly hypercholesterolaemic ( ≥ 5 mmol/l and < 7·5 mmol/l) men and women assigned to one of three diet arms (25 % energy (E%) protein; 45 E% carbohydrate; 30 E% fat, at energy requirements for weight maintenance): (1) minimal β-glucan (control); (2) low-dose oat β-glucan (1·5 g β-glucan; oats low - OL) or (3) higher dose oat β-glucan (3·0 g β-glucan; oats high - OH). Changes in total cholesterol and LDL-cholesterol (LDL-C) from baseline were assessed using a linear mixed model and repeated-measures ANOVA, adjusted for weight change. Total cholesterol reduced significantly in all groups ( - 7·8 (sd 13·8) %, - 7·2 (sd 12·4) % and - 5·5 (sd 9·3) % in the OH, OL and control groups), as did LDL-C ( - 8·4 (sd 18·5) %, - 8·5 (sd 18·5) % and - 5·5 (sd 12·4) % in the OH, OL and control groups), but between-group differences were not significant. In responders only (n 60), β-glucan groups had higher reductions in LDL-C ( - 18·3 (sd 11·1) % and - 18·1 (sd 9·2) % in the OH and OL groups) compared with controls ( - 11·7 (sd 7·9) %; P = 0·044). Intakes of oat β-glucan were as effective at doses of 1·5 g/d compared with 3 g/d when provided in different food formats that delivered similar amounts of soluble β-glucan.

Weight loss effects from vegetable intake: a 12-month randomised controlled trial.

Background/Objectives:Direct evidence for the effects of vegetable intake on weight loss is qualified. The study aimed to assess the effect of higher vegetable consumption on weight loss.Subjects/Methods:A single blind parallel controlled trial was conducted with 120 overweight adults (mean body mass index=29.98 kg/m2) randomised to two energy deficit healthy diet advice groups differing only by doubling the serving (portion) sizes of vegetables in the comparator group. Data were analysed as intention-to-treat using a linear mixed model. Spearmans rho bivariate was used to explore relationships between percentage energy from vegetables and weight loss.Results:After 12 months, the study sample lost 6.5±5.2 kg (P<0.001 time) with no difference between groups (P>0.05 interaction). Both groups increased vegetable intake and lost weight in the first 3 months, and the change in weight was significantly correlated with higher proportions of energy consumed as vegetables (rho=–0.217, P=0.024). Fasting glucose, insulin and triglyceride levels decreased (P<0.001 time) and high-density lipoprotein cholesterol levels increased (P<0.001 time), with no difference between groups. Weight loss was sustained for 12 months by both groups, but the comparator group reported greater hunger satisfaction (P=0.005).Conclusions:Advice to consume a healthy low-energy diet leads to sustained weight loss, with reductions in cardiovascular disease risk factors regardless of an emphasis on more vegetables. In the short term, consuming a higher proportion of the dietary energy as vegetables may support a greater weight loss and the dietary pattern appears sustainable.

Short term effects of energy restriction and dietary fat sub-type on weight loss and disease risk factors

BACKGROUND AND AIMS Decreasing energy intake relative to energy expenditure is the indisputable tenet of weight loss. In addition to caloric restriction modification of the type of dietary fat may provide further benefits. The aim of the present study was to examine the effect of energy restriction alone and with dietary fat modification on weight loss and adiposity, as well as on risk factors for obesity related disease. METHODS AND RESULTS One-hundred and fifty overweight men and women were randomized into a 3month controlled trial with four low fat (30% energy) dietary arms: (1) isocaloric (LF); (2) isocaloric with 10% polyunsaturated fatty acids (LF-PUFA); (3) low calorie (LF-LC) (-2MJ); (4) low calorie with 10% PUFA (LF-PUFA-LC). Primary outcomes were changes in body weight and body fat and secondary outcomes were changes in fasting levels of leptin, insulin, glucose, lipids and erythrocyte fatty acids. Changes in dietary intake were assessed using 3day food records. One-hundred and twenty-two participants entered the study and 95 completed the study. All groups lost weight and body fat (P<0.0001 time effect for both), but the LC groups lost more weight (P=0.026 for diet effect). All groups reduced total cholesterol levels (P<0.0001 time effect and P=0.017 intervention effect), but the LC and PUFA groups were better at reducing triacylglycerol levels (P=0.056 diet effect). HDL increased with LF-LC and LF-PUFA but not with LF-PUFA-LC (0.042 diet effect). The LF and LF-LC groups reported greater dietary fat reductions than the two PUFA groups (P=0.043). CONCLUSION Energy restriction has the most potent effect on weight loss and lipids, but fat modification is also beneficial when energy restriction is more modest.

Pork, beef and chicken have similar effects on acute satiety and hormonal markers of appetite

The effects of three different meat-containing breakfast meals (pork, beef or chicken) on acute satiety and appetite regulatory hormones were compared using a within-subjects study design. Thirty fasting non-smoking pre-menopausal women attended a research centre on three test days to consume, a meat-containing meal matched in energy (kJ) and protein content, palatability, and appearance. No difference was found between meat groups for either energy intake or macronutrient profile of food consumed at a subsequent ad libitum buffet lunch, or over the rest of the day. Visual Analogue Scale (VAS) ratings for hunger and satiety over an 180 min period did not differ between test meals. After consumption of the test meals, a significant difference was found in PYY response between pork and chicken meals (P=0.027) but not for levels of CCK, ghrelin, insulin or glucose. This study positions pork, beef, and chicken as equal in their effect on satiety and release of appetite-related intestinal hormones and of insulin.

Using data mining to predict success in a weight loss trial

BACKGROUND Traditional methods for predicting weight loss success use regression approaches, which make the assumption that the relationships between the independent and dependent (or logit of the dependent) variable are linear. The aim of the present study was to investigate the relationship between common demographic and early weight loss variables to predict weight loss success at 12 months without making this assumption. METHODS Data mining methods (decision trees, generalised additive models and multivariate adaptive regression splines), in addition to logistic regression, were employed to predict: (i) weight loss success (defined as ≥5%) at the end of a 12-month dietary intervention using demographic variables [body mass index (BMI), sex and age]; percentage weight loss at 1 month; and (iii) the difference between actual and predicted weight loss using an energy balance model. The methods were compared by assessing model parsimony and the area under the curve (AUC). RESULTS The decision tree provided the most clinically useful model and had a good accuracy (AUC 0.720 95% confidence interval = 0.600-0.840). Percentage weight loss at 1 month (≥0.75%) was the strongest predictor for successful weight loss. Within those individuals losing ≥0.75%, individuals with a BMI (≥27 kg m-2 ) were more likely to be successful than those with a BMI between 25 and 27 kg m-2 . CONCLUSIONS Data mining methods can provide a more accurate way of assessing relationships when conventional assumptions are not met. In the present study, a decision tree provided the most parsimonious model. Given that early weight loss cannot be predicted before randomisation, incorporating this information into a post randomisation trial design may give better weight loss results.

What do the terms wellness and wellbeing mean in dietary practice: an exploratory qualitative study examining women's perceptions

BACKGROUND Wellness and wellbeing are terms associated with health within dietetic discourse. More broadly, these terms are found in social discourse as represented in food and nutrition consumer communications. With the increasing requirement for evidence-based healthcare, there is an imperative to understand whether these terms are meaningful to individuals typically targeted for nutrition interventions and whether there are any implications for dietetic education. METHODS To explore the understanding of these terms, eight semi-structured focus groups were conducted with 32 female participants (age range 23-79 years) who were actively engaged in managing their health. Overall understanding of the terms, factors that impacted perceptions and any relationships with food behaviour were investigated with the groups. Group discussions were transcribed verbatim and each transcript was examined by two researchers. Inductive analysis linking codes into main thematic categories was conducted using the constant comparison approach across the full data set. RESULTS Wellness and wellbeing were identified as meaningful terms associated with health. A theoretical framework of wellness and wellbeing reflecting these meanings was developed linking four dominant thematic areas. These were Desired outcomes (most sought after result); Taking control (self management strategies); Internal influences (various personal inner factors influencing behaviours); and External influences (plethora of peripheral factors influencing behaviours). CONCLUSIONS Wellness and wellbeing are terms that are relevant and aspirational for individuals typically targeted for nutrition intervention. A theoretical framework of dominant areas of influence on notions of wellness and wellbeing was identified. This theoretical framework is worthy of further research to determine usefulness and effectiveness in dietetic practice settings.

Conversion of Australian food composition data from AUSNUT1999 to 2007 in the Clinical Trial Context

An Australian food composition database, AUSNUT1999, does not include long chain omega-3 polyunsaturated fatty acid (LC omega-3 PUFA) data. Measurement of the fatty acid content of diets initially analysed using AUSNUT1999 requires conversion to AUSNUT2007, an updated database inclusive of LC omega-3 PUFA. The aim of this study was to convert clinical trial dietary data from AUSNUT1999 to AUSNUT2007 and measure LC omega-3 PUFA intake. Clinical trial diet history (DH) data was converted from AUSNUT1999 to 2007 using a staged approach. Macronutrient intake from AUSNUT1999 and 2007 were calculated and compared via paired t-tests and Wilcoxon Signed Ranks tests. Mean dietary LC omega-3 PUFA intake and the percentage contribution of food groups to total LC omega-3 PUFA were then calculated. DHs were collected at baseline (n = 118), three months (n = 86), and 12 months (n = 64). The accuracy of the conversion process improved with time, with no significant difference between most macronutrients at 12 months. Mean LC n-3 PUFA intake was 441.87 mg at baseline, 521.07 mg at 3 months, and 442.40 mg at 12 months, and was predominantly provided by fish and seafood, followed by meat products. This study allowed for the measurement of LC omega-3 intake, which was previously impossible using the AUSNUT1999 database.