Effects of macronutrient composition of the diet on body fat in indigenous people at high risk of type 2 diabetes

Do health education initiatives assist socioeconomically disadvantaged populations? A systematic review and meta-analyses

BACKGROUND

Health education interventions are considered critical for the prevention and management of conditions of public health concern. Although the burden of these conditions is often greatest in socio-economically disadvantaged populations, the effectiveness of interventions that target these groups is unknown. We aimed to identify and synthesize evidence of the effectiveness of health-related educational interventions in adult disadvantaged populations.

METHODS

We pre-registered the study on Open Science Framework https://osf.io/ek5yg/ . We searched Medline, Embase, Emcare, and the Cochrane Register from inception to 5/04/2022 to identify studies evaluating the effectiveness of health-related educational interventions delivered to adults in socio-economically disadvantaged populations. Our primary outcome was health related behaviour and our secondary outcome was a relevant biomarker. Two reviewers screened studies, extracted data and evaluated risk of bias. Our synthesis strategy involved random-effects meta-analyses and vote-counting.

RESULTS

We identified 8618 unique records, 96 met our criteria for inclusion - involving more than 57,000 participants from 22 countries. All studies had high or unclear risk of bias. For our primary outcome of behaviour, meta-analyses found a standardised mean effect of education on physical activity of 0.05 (95% confidence interval (CI) = -0.09-0.19), (5 studies, n = 1330) and on cancer screening of 0.29 (95% CI = 0.05-0.52), (5 studies, n = 2388). Considerable statistical heterogeneity was present. Sixty-seven of 81 studies with behavioural outcomes had point estimates favouring the intervention (83% (95% CI = 73%-90%), p < 0.001); 21 of 28 studies with biomarker outcomes showed benefit (75% (95%CI = 56%-88%), p = 0.002). When effectiveness was determined based on conclusions in the included studies, 47% of interventions were effective on behavioural outcomes, and 27% on biomarkers.

CONCLUSIONS

Evidence does not demonstrate consistent, positive impacts of educational interventions on health behaviours or biomarkers in socio-economically disadvantaged populations. Continued investment in targeted approaches, coinciding with development of greater understanding of factors determining successful implementation and evaluation, are important to reduce inequalities in health.

Effects of a low-carbohydrate/high-protein diet on metabolic health in individuals with chronic spinal cord injury: An exploratory analysis of results from a randomized controlled trial

We explored the impact of a low-carbohydrate/high-protein diet (LC/HP, ~30% energy from protein, 40% energy from carbohydrate) on indices of metabolic function and body composition in individuals with chronic spinal cord injury (SCI). Adults with SCI (≥3 years post-injury, C4-L2, AIS A-D) and insulin resistance or pre-diabetes were randomly assigned to an 8-week iso-caloric LC/HP diet group (n = 11) or control group (n = 14). All LC/HP meals were delivered weekly to participants' homes, and participants in the control group consumed their habitual diet. Each participant underwent an oral glucose tolerance test (OGTT) to assess glucose tolerance, insulin, area under the curve (AUC) for glucose and insulin, Matsuda Index, glucose-stimulated insulin secretion (GSIS), disposition index, and hepatic insulin extraction (HIE). Fasting blood lipid and inflammation were assessed, and body composition was estimated using dual-energy x-ray absorptiometry. A linear mixed model was used to evaluate the main effect of diet, time, and their interaction. Compared to the control group, participants in the LC/HP group had reduced total body fat mass (LC/HP: -5.9%, Control: 0.7%), visceral fat mass (LC/HP: -16.2%, Control: 5.2%), total- (LC/HP: -20.1, Control: 3.7 mg/dl), and LDL-cholesterol (LC/HP: -13.9, Control: 3.1 mg/dl) (pdiet*time  < 0.05 for all). Regardless of group, AUCinsulin and peak insulin during the OGTT decreased, and HIE increased over time (ptime  < 0.05). A trend for diet*time interaction was observed for glucoseOGTT120min (LC/HP: -20.7, Control: 3.0 mg/dl, pdiet*time  = 0.09) and peak C-peptide (LC/HP: -2.1, Control: 0.0 ng/ml, pdiet*time  = 0.07). HDL-cholesterol, lean body mass, Matsuda Index, fasting glucose, insulin, insulinOGTT120min , AUCglucose , pancreatic beta cell function (GSIS, disposition index), and inflammation (C-reactive protein, IL-6, IL-8, IL-10, TNF-α) did not change over time. In conclusion, our results suggest that individuals with SCI and insulin resistance may adopt an LC/HP diet to improve body composition and lipid profiles. Its impact on glucose metabolism and inflammation remains inconclusive and warrants future investigations.

Effects of lifestyle interventions on weight amongst Pasifika communities: A systematic review and meta-analysis

BACKGROUND

Pasifika populations experience high incidence and prevalence of obesity and T2DM. However, no international review of lifestyle intervention studies amongst Pasifika communities exists. This study seeks to identify the effect and translatability of lifestyle strategies on weight amongst Pasifika populations.

METHODS

Lifestyle studies involving ≥90% adult Pasifika participants measuring weight change were eligible for inclusion. Database searching was carried out up to December 2021. Databases searched were MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCOhost) and ProQuest Central. Risk of bias was assessed using RoB2 (RCTs) and the National Heart, Lung and Blood Institute (NHLBI) quality assessment tool. Meta-analysis and meta-regression used a bivariate random-effects model. Strategies were coded against pre-identified components of the newly proposed Cultural and Sustainability Assessment of Intervention (CSAI) framework.

FINDINGS

Twenty-three studies (n = 4258 participants) met inclusion and exclusion criteria. Thirty-two lifestyle strategies targeting weight loss (WL) and 7 targeting weight maintenance (WM) were extracted. Meta-analysis estimates small but significant effect of -0.26 standard deviations (95% CI -0.51 to -0.02), with RCTs demonstrating a non-significant effect of -0.23 standard deviations (95% CI -0.49 to 0.035). Culturally relevant strategies included community and peer support facilitators and team-based activities. The CSAI identified 14 out of 23 studies with low cultural competency and sustainability scores (<60%).

INTERPRETATION

Qualitative and quantitative analysis show tailored lifestyle interventions has had an estimated small but beneficial effect on WL amongst Pasifika communities. Potential for tailored interventions design to incorporate psychosocial and behavioural considerations. The CSAI has the potential for systematically identifying cultural and sustainability components of efficacy in interventions.

FUNDING

This review was funded under Western Sydney University's Postgraduate Research Scholarship.

Cultural adaptation of health interventions including a nutrition component in Indigenous peoples: a systematic scoping review

BACKGROUND

Indigenous populations throughout the world experience poorer health outcomes than non-indigenous people. The reasons for the health disparities are complex and due in part to historical treatment of Indigenous groups through colonisation. Evidence-based interventions aimed at improving health in this population need to be culturally safe. However, the extent to which cultural adaptation strategies are incorporated into the design and implementation of nutrition interventions designed for Indigenous peoples is unknown. The aim of this scoping review was to explore the cultural adaptation strategies used in the delivery of nutrition interventions for Indigenous populations worldwide.

METHODS

Five health and medical databases were searched to January 2020. Interventions that included a nutrition component aimed at improving health outcomes among Indigenous populations that described strategies to enhance cultural relevance were included. The level of each cultural adaptation was categorised as evidential, visual, linguistic, constituent involving and/or socio-cultural with further classification related to cultural sensitivity (surface or deep).

RESULTS

Of the 1745 unique records screened, 98 articles describing 66 unique interventions met the inclusion criteria, and were included in the synthesis. The majority of articles reported on interventions conducted in the USA, Canada and Australia, were conducted in the previous 10 years (n = 36) and focused on type 2 diabetes prevention (n = 19) or management (n = 7). Of the 66 interventions, the majority included more than one strategy to culturally tailor the intervention, combining surface and deep level adaptation approaches (n = 51), however, less than half involved Indigenous constituents at a deep level (n = 31). Visual adaptation strategies were the most commonly reported (n = 57).

CONCLUSION

This paper is the first to characterise cultural adaptation strategies used in health interventions with a nutrition component for Indigenous peoples. While the majority used multiple cultural adaptation strategies, few focused on involving Indigenous constituents at a deep level. Future research should evaluate the effectiveness of cultural adaptation strategies for specific health outcomes. This could be used to inform co-design planning and implementation, ensuring more culturally appropriate methods are employed.

The effect of plant-based dietary patterns on blood pressure: a systematic review and meta-analysis of controlled intervention trials

OBJECTIVES

The consumption of strict vegetarian diets with no animal products is associated with low blood pressure (BP). It is not clear whether less strict plant-based diets (PBDs) containing some animal products exert a similar effect. The main objective of this meta-analysis was to assess whether PBDs reduce BP in controlled clinical trials.

METHODS

We searched Cumulative Index to Nursing and Allied Health Literature, Medline, Embase, and Web of Science to identify controlled clinical trials investigating the effect of PBDs on BP. Standardized mean differences in BP and 95% confidence intervals were pooled using a random effects model. Risk of bias, sensitivity, heterogeneity, and publication bias were assessed.

RESULTS

Of the 790 studies identified, 41 clinical trials met the inclusion criteria (8416 participants of mean age 49.2 years). In the pooled analysis, PBDs were associated with lower SBP [Dietary Approach to Stop Hypertension -5.53 mmHg (95% confidence intervals -7.95,-3.12), Mediterranean -0.95 mmHg (-1.70,-0.20), Vegan -1.30 mmHg (-3.90,1.29), Lacto-ovo vegetarian -5.47 mmHg (-7.60,-3.34), Nordic -4.47 mmHg (-7.14,-1.81), high-fiber -0.65 mmHg (-1.83,0.53), high-fruit and vegetable -0.57 mmHg (-7.45,6.32)]. Similar effects were seen on DBP. There was no evidence of publication bias and some heterogeneity was detected. The certainty of the results is high for the lacto-ovo vegetarian and Dietary Approach to Stop Hypertension diets, moderate for the Nordic and Mediterranean diets, low for the vegan diet, and very low for the high-fruit and vegetable and high-fiber diets.

CONCLUSION

PBDs with limited animal products lower both SBP and DBP, across sex and BMI.

Ethnicity and Metabolic Syndrome: Implications for Assessment, Management and Prevention

The metabolic syndrome (MetS) is a constellation of cardiometabolic risk factors that identifies people at increased risk for type 2 diabetes and cardiovascular disease. While the global prevalence is 20%–25% of the adult population, the prevalence varies across different racial/ethnic populations. In this narrative review, evidence is reviewed regarding the assessment, management and prevention of MetS among people of different racial/ethnic groups. The most popular definition of MetS considers race/ethnicity for assessing waist circumference given differences in visceral adipose tissue and cardiometabolic risk. However, defining race/ethnicity may pose challenges in the clinical setting. Despite 80% of the world’s population being of non-European descent, the majority of research on management and prevention has focused on European-derived populations. In these studies, lifestyle management has proven an effective therapy for reversal of MetS, and randomised studies are underway in specific racial/ethnic groups. Given the large number of people at risk for MetS, prevention efforts need to focus at community and population levels. Community-based interventions have begun to show promise, and efforts to improve lifestyle behaviours through alterations in the built environment may be another avenue. However, careful consideration needs to be given to take into account the unique cultural context of the target race/ethnic group.

Cardio-metabolic disease genetic risk factors among Māori and Pacific Island people in Aotearoa New Zealand: current state of knowledge and future directions

CONTEXT

Cardio-metabolic conditions in Aotearoa New Zealand (NZ) Māori and non-indigenous Polynesian (Pacific) populations have been increasing in prevalence and severity, especially over the last two decades.

OBJECTIVES

To assess knowledge on genetic and non-genetic risk factors for cardio-metabolic disease in the Māori and Pacific populations residing in Aotearoa NZ by a semi-systematic review of the PubMed database. To outline possible future directions in genetic epidemiological research with Māori and Pacific communities.

RESULTS

There have been few studies to confirm that risk factors in other populations also associate with cardio-metabolic conditions in Māori and Pacific populations. Such data are important when interventions are considered. Genetic studies have been sporadic, with no genome-wide association studies done.

CONCLUSIONS

Biomedical research with Māori and Pacific communities is important to reduce the prevalence and impact of the cardio-metabolic diseases, as precision medicine is implemented in other Aotearoa NZ populations using overseas findings. Genuine engagement with Māori and Pacific communities is needed to ensure positive outcomes for genetic studies, from data collection through to analysis and dissemination. Important is building trust, understanding by researchers of fundamental cultural concepts and implementing protocols that minimise risks and maximise benefits. Approaches that utilise information such as genealogical information and whole genome sequencing technologies will provide new insights into cardio-metabolic conditions-and new interventions for affected individuals and families.

Lifestyle Interventions for People with, and at Risk of Type 2 Diabetes in Polynesian Communities: A Systematic Review and Meta-Analysis

There is evidence that lifestyle intervention among Polynesian people can reduce diabetes incidence and complications, but this evidence has not been systematically reviewed. The aim of this study was to systematically review the efficacy of lifestyle interventions, targeting the prevention and management of type 2 diabetes among Polynesian people. MEDLINE, Web of Science, Cochrane Library, and Embase were searched to find randomised controlled trials (RCTs) and pre-post studies. Eight studies (four RCTs and four pre-post studies) with 1590 participants met the inclusion criteria. The data on health outcomes that was reported in these studies included blood pressure, body mass index, waist circumference, weight, and glycated haemoglobin (HbA1c). The meta-analyses showed that the interventions had resulted in statistically significant reductions in systolic blood pressure (SBP) across four of the studies (WMD, −9.93 mmHg; 95% Cl, −10.77 to −9.09; and p < 0.00001). However, the effects on weight across five of the studies (WMD, −1.15 kg; 95% Cl, −2.80 to 0.51; p = 0.18) and the HbA1c levels across two of the studies (WMD, −0.38%; 95% Cl, −1.15 to 0.39; and p = 0.33) were not statistically significant. This review provides evidence that lifestyle interventions may be effective in achieving modest reductions in SBP in Polynesian people. Further research is needed to fully assess the effectiveness of these interventions in this population long-term.