Effects of Nutritional Interventions on Cardiovascular Disease Health Outcomes in Aboriginal and Torres Strait Islander Australians: A Scoping Review

Nutrition interventions can support Aboriginal and Torres Strait Islander peoples to reduce their risk of cardiovascular disease (CVD). This review examines nutritional interventions aiming to improve CVD outcomes and appraises peer-reviewed interventions using an Aboriginal and Torres Strait Islander Quality Appraisal Tool. Five electronic databases and grey literature were searched, applying no time limit. Two reviewers completed the screening, data extraction and quality assessment independently. The study quality was assessed using the South Australian Health and Medical Research Institute and the Centre of Research Excellence in Aboriginal Chronic Disease Knowledge Translation and Exchange Aboriginal and Torres Strait Islander Quality Appraisal Tool (QAT). Twenty-one nutrition programs were included in this review. Twelve reported on anthropometric measurements, ten on biochemical and/or hematological measurements and sixteen on other outcome domains. Most programs reported improvements in measurable CVD risk factors, including reduced body mass index (BMI), waist circumference (WC), weight, blood pressure and improved lipid profiles. Most programs performed well at community engagement and capacity strengthening, but many lacked the inclusion of Indigenous research paradigms, governance and strengths-based approaches. This review highlights the need for contemporary nutrition programs aimed at improving cardiovascular health outcomes to include additional key cultural components.


Introduction
Aboriginal and Torres Strait Islander Australians are strongly connected to "country" (land, waterways, and seas) through family, spiritual and traditional links that contribute to their health and wellbeing. History tells us that practices, policies and legislations directed towards Aboriginal and Torres Strait Islander peoples during Australia's early colonial years resulted in their forceful removal from lands and a disconnection from "country" that contributed to sudden changes in their dietary and lifestyle behaviours [1]. Traditionally, the nutrient composition of Aboriginal and Torres Strait Islander peoples' diet was high in protein, fibre, polyunsaturated fats and complex unrefined carbohydrates [2]. The low energy density of traditional diets along with the energy expended in food procurement processes provided a natural constraint on energy intake, and research suggests that precolonisation Aboriginal and Torres Strait Islander peoples were physically fit and lean [3]. The resulting loss of traditional lands, waterways and food practices, along with food insecurity and geographic factors, has changed their diet into a heavily processed western diet [4][5][6]. A western diet has been linked to the risk of developing Cardiovascular disease (CVD) and/or other complications as the diet features high amounts of saturated fat, red meat-based protein, added sugars, salt, processed and fast-foods, as well as low levels of fibre, certain micronutrients, wholegrains, fruit and vegetables [7].
Cardiovascular disease is a class of disorders affecting the heart and blood vessels and includes: coronary heart disease, ischemic heart disease, cerebrovascular disease, stroke, and others [8]. Cardiovascular disease risk factors include smoking, excessive alcohol, lack of physical activity, being overweight or obese, not eating the recommended amounts of fruit and vegetables and high blood pressure, blood glucose and cholesterol [9,10]. While CVD is a leading and serious disease in Australia [11], Aboriginal and Torres Strait Islander peoples have higher rates of CVD-related hospitalization and death compared to non-Indigenous Australians [12]. Addressing modifiable risk factors, such as diet, would help to prevent 37% of the burden of disease in Aboriginal and Torres Strait Islander populations [13].
The release of the Social Justice Report in 2005 resulted in a push towards achieving equality for Aboriginal and Torres Strait Islander peoples in relation to health and life expectancy [14]. Subsequently, this led to the collaborative initiation of Close the Gap campaign and the government response, through Closing the Gap [15]. One of the main considerations articulated for achieving equality in health outcomes is that research and programs are co-developed with communities and conducted in an appropriate way suitable to the needs, culture and paradigm of Aboriginal and Torres Strait Islander peoples. Further, there is an important emphasis on taking a strengths-based and preventative health approach [16,17]. Nutrition promotion is an important part of cardiovascularoriented health promotion and food and water security are key to allowing Aboriginal and Torres Strait Islander people to eat a healthy diet [18]. While previous health and nutrition programs have targeted Aboriginal and Torres Strait Islander peoples, none have been appropriately appraised to determine if they are culturally suitable, and few have been adequately evaluated [19,20]. Evaluations are crucial to understanding the viability, effectiveness and impact of nutrition programs as they inform nutrition policy and practice [21]. Moreover, they provide the evidence base necessary for funding and can enhance community support and awareness when released appropriately to stakeholders and the general public.
Cultural awareness, community engagement and partnerships, combined leadership, and sustainable resources are integral components of programs that aim to improve the health of Aboriginal and Torres Strait Islander peoples [19]. However, the existing frameworks and strategies used to guide the design and evaluation of Aboriginal and Torres Strait Islander nutritional programs have lacked appropriate tools to evaluate these programs and principles [22,23]. Aboriginal and Torres Strait Islander Quality Appraisal Tools (QAT) offers a credible and rigorous assessment to ensure programs are designed and delivered in a culturally appropriate manner [24]. A scoping review was selected for its ability to map all the relevant literature, including scientific peer-reviewed publications, as well as unpublished grey literature, to fill in the gaps in knowledge on this topic [25]. This review (1) examines the effects of nutrition interventions that aim to improve CVD outcomes in Aboriginal and Torres Strait Islander peoples; and (2) assesses the cultural appropriateness of programs with scientific peer-reviewed evaluations using the Aboriginal and Torres Strait Islander QAT.

Protocol and Registration
The performance of this scoping review followed the Arksey & O'Malley framework [26] and the findings are reported in accordance with the Joanna Briggs Institute updated methodological guidance for scoping reviews [27]. The protocol was developed and published on the Open Science Platform https://osf.io/z38gt/, accessed on 12 April 2021.

Participants
Aboriginal and Torres Strait Islander peoples of any age, with or without co-morbidities and residing in Australia were included. Programs were excluded if Aboriginal and Torres Strait Islander peoples did not make up more than 50% of the sample population or the data were unable to be extracted from non-indigenous Australians.

Concept
Programs or studies describing nutritional interventions that aim to improve CVD health outcomes were included. This included programs or studies with or without cointerventions targeting additional lifestyle diseases, as well as programs aiming to improve food security and dietary quality. Interventions that focused only on nutrient supplementation were excluded. For the published peer-reviewed studies, the interventions were required to have at least one marker from the following two outcome domains; (1) anthropometric measures (i.e., waist circumference (WC), body mass index (BMI), weight, hip measurements, waist-to-hip ratio (WHR) and fat mass); (2) biochemical and/or hematological biomarkers (i.e., total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), blood glucose level (BGL), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP), fasting insulin and glycated haemoglobin (HbA1c). An additional program outcome category, "other", was included to capture any additional information (mostly relevant for non-published programs).

Context
This review considered programs conducted in the community at large from all the regions of Australia. This included programs delivered through outpatient facilities or clinics. Programs conducted in institutional settings (i.e., hospitals or aged care facilities) were excluded as disease or illnesses may influence dietary requirements and intake.

Types of Studies
To understand the extent, range and nature of all the programs aiming to improve CVD outcomes in Aboriginal and Torres Strait Islander peoples, the eligibility criteria for the included study types was broad. Primary study designs, conference proceedings, posters or abstracts, editorials, commentaries, perspectives, book chapters, newsletters, dissertations, theses, and government-produced reports and documents were all included. Systematic reviews and meta-analysis were excluded. The language of programs was restricted to English and there was no set date limit for the year of program dissemination.

Search Strategy
An initial limited search was conducted on MEDLINE and the Australian Indigenous HealthInfoNet to identify articles on the topic. A full search strategy was developed based on the key words contained in the titles and abstracts, as well as indexed terms used to classify the articles. A full search was conducted on Ovid (Medline and Embase), Scopus and Informit (Family and Society Collection and Indigenous Collection). Grey literature sources included the Australian Indigenous HealthInfoNet, Google Scholar and Lowitja Institute. The search strategy for MEDLINE is shown in Supplementary Table S1, conducted in March 2021. The reference lists of studies that were selected for full text screening were examined for additional programs.

Selection Process
The identified records from the full search were imported into EndNote X9.3.3. (Clarivate Analytics, PA, USA) for screening. The titles and abstracts of the retrieved studies were screened against the inclusion criteria by two independent reviewers (C.B. and H.M.). For the studies with the potential to be included, full texts were retrieved and attached in EndNote. Two reviewers screened against the inclusion and exclusion criteria independently. The reasons for exclusion after full text screening were recorded in EndNote and any discrepancies between the reviewers that arose throughout the process was resolved through discussion or consultation with a third reviewer (A.D.). The search results are presented in a PRISMA flow diagram ( Figure 1).

Data Charting
The data was charted using a standardized data charting form based on an existing framework for scoping reviews [26,27]. The following information was extracted for each included program: program reference, aim(s), intervention summary, timeframe (duration and time to follow up), target population, setting, outcome measures (anthropometric, biochemical and/or hematological biomarkers or other) and program status (completed, active or unclear). Using Microsoft Excel, two independent researchers (C.B. and H.M.) independently extracted data and resolved any discrepancies through discussion or consultation with a third reviewer (A.D.). In cases in which one program had multiple reports, all the reports were included if they met the inclusion criteria to ensure that the full details of the program were recorded. The authors of papers or relevant government bodies were contacted if missing or additional data needed to be requested.

Critical Appraisal
To assess the quality of the peer-reviewed research and its cultural appropriateness, the 2018 South Australian Health and Medical Research Institute (SAHMRI) and the Centre of Research Excellence in Aboriginal Chronic Disease Knowledge Translation and Exchange (CREATE) Aboriginal and Torres Strait Islander Quality Appraisal Tool (QAT) was implemented [24]. Two independent reviewers (C.B. and H.M.) used the Aboriginal and Torres Strait Islander Quality Appraisal Tool's Companion Document [28] as well as the Practical Guide for Researchers from the Lowitja Institute [29] to guide their response to the 14-question QAT, with disagreements resolved through consultation with a third Aboriginal reviewer (J.C.).
The responses to the QAT included yes, partial, unclear and no. The Yes category was assigned to studies that clearly provided written evidence in favour of the question. The Partial category was assigned to studies that provided some evidence, or brief evidence in favour of the question. The Unclear category was assigned to studies that may have actioned question items but did not explicitly report full or partial evidence. The No category was assigned to studies that did not report any evidence or reported evidence not in favour of the question item. These responses were presented in an adapted traffic light plot using the colours: green, blue, orange and red. A program was considered more culturally appropriate and of higher research quality if it received more "yes" responses. Inversely, a program was considered less culturally appropriate and of lower research quality if it received more "no" responses. A final rating of "very good" was assigned to papers that answered yes to over 75% of questions, "good" to those that answered yes to over 50% of questions, "fair" to those that answered yes to fewer than 50% of questions, and "poor" to those that answered yes to fewer than 25% of questions. To score how well each question performed, three points were assigned for "yes-green", two points for "partially-blue", one point for "unclear-orange" and no points for "no-red".

Synthesis of Results
The results are presented in tabular form, with an accompanying narrative summary to describe the results in relation to the scoping review's aims. Table 1 includes programs published in grey literature, while Table 2 includes programs published in scientific peerreviewed literature. The results were interpreted through a decolonized lens privileging Aboriginal and Torres Strait ways of knowing [30,31]. The findings of this review will be used to inform future community-led nutrition interventions aiming to improve CVD disease outcomes in Aboriginal and Torres Strait Islander peoples.

Search Results
The academic database search yielded a total number of 384 records using the search strategy on five electronic databases (Medline = 124, Embase = 157, Scopus = 81, Informit Indigenous Collection = 21, Informit Family and Society Collection = 1). This was reduced to 235 after 149 duplicates were removed. A total of 235 records were then screened, with 225 records excluded. Ten reports were sought for full text retrieval and assessed for eligibility. Of these ten reports, a total of six reports representing five programs were identified through databases and included in this review.
A total of 430 records were identified via other methods, of which 22 full text reports were retrieved. Of these 22 reports, four were excluded as they were not primary research. A total of 18 reports, representing 16 programs, were identified through other methods and were included in this review. The flowchart in Figure 1 illustrates the process of the selection of sources of evidence.

Biochemical and/or Haematological Outcomes
A total of 10 programs reported on biochemical and/or hematological outcomes [42][43][44][45][46]48,49,[51][52][53][54][55]. Significant reduction in TC was the most common improvement in this category and was seen in four programs [44,46,52,53], while a significant reduction in the prevalence of age-adjusted hypercholesterolemia (HC) was reported in one program [54,55] and a decrease in the odds (OR 0.29) of HC at eight years' follow-up for another [53]. Three programs produced significant reductions in HDL-C [42,46,53], while one program reported an increase, although its statistical significance is unclear [43]. One program reported significant improvements in targeted achievements in LDL-C [44]. A significant reduction in TG was reported for one program [46], while another program reported a significant increase in TG and dyslipidemia at the eight-year follow-up [53]. Three programs produced a significant decrease in SBP [42,48,49,52] and DBP [46,48,49,52].
One program reported significant reductions in BGL [42], while another program saw significant decreases in two-hour plasma glucose, fasting glucose and fasting insulin; however, these reductions were not sustained [54,55].

Quality Appraisal
The quality appraisal results are presented in Figure 2 with green representing (yes), blue (partially), orange (unclear) and red (no) for the responses to 126 questions. Green represented 35% of all the responses, followed by orange (28%), blue (19%) and red (18%). Islander individuals?; Q14 Did everyone involved in the research have opportunities to learn from each other? The symbol § represents the overall rating of peer-reviewed programs. A final rating of "very good" was assigned to papers that answered yes to over 75% of questions, "good" to those that answered yes to over 50% of questions, "fair" to those that answered yes to fewer than 50% of questions, and "poor" to those that answered yes to fewer than 25% of questions.
The program that performed best in terms of overall cultural appropriateness was by Davey et al. 2014 [47]. Three programs were rated as good [48,49,52,54,55] and the remaining five programs were rated as poor [45,46,50,51,53]. No trend was apparent regarding the date of programs and the ranking of cultural appropriateness, despite the most recent program receiving the highest ranking [47].
The three questions that received the highest score across all the programs were: Question 2, "Was the community consultation and engagement appropriately inclusive?"; Question 12, "Did the research benefit the participants and Aboriginal and Torres Strait Islander communities?"; and Question 13, "Did the research demonstrate capacity strengthening for Aboriginal and Torres Strait Islander individuals?". By contrast, the three lowestperforming questions were; Question 4, "Did the research have Aboriginal and Torres Strait Islander governance?"; Question 9, "Was the research guided by an Indigenous research paradigm?" and Question 10, "Does the research take a strengths-based approach, acknowledging and moving beyond practices that have harmed Aboriginal and Torres Strait Islander peoples in the past?".

Discussion
This scoping review is the first to map the evidence relating to the effectiveness of nutrition programs aiming to improve CVD outcomes in Aboriginal and Torres Strait Islander peoples and to appraise peer-reviewed interventions using a culturally appropriate Aboriginal and Torres Strait Islander QAT. Among the 21 programs identified, 12 programs were from unpublished research and nine from published research. Most programs reported improvements in measurable risk factors for CVD, including reduced BMI, WC, weight, blood pressure and improved lipid profiles. Other improvements included knowledge, skills, well-being and quality of life. It appears that a multifaceted education approach was consistently implemented. The predominant topics included healthy eating, weight loss and management, food budgeting, food label reading, and the benefits of exercise. Incorporating physical activity components was a common feature of many of the programs, which likely contributed to improved metabolic control. From the nine peer-reviewed publications that were critically appraised and evaluated using the QAT, four programs that were deemed more culturally appropriate were likely to be associated with program sustainability [47][48][49]52,54,55] and may still be active within communities [48,49,52,54,55].
Program evaluations help us to demonstrate impact and improve program design and implementation, as well as to drive support for funding. This scoping review found that not all programs had been evaluated and that of those that were evaluated, few were peer-reviewed. Peer-reviewed programs offered greater detail on anthropometric and biochemical and/or haematological measurements than non-peer-reviewed programs. Despite the limited number of peer-reviewed programs, the outcomes generally supported previous findings in that targeted cardiovascular programs incorporating both nutrition and physical activity are beneficial in reducing CVD risk and improving clinical outcomes [56,57]. Other qualitative and behavioural outcomes lacked consistency, were reported less frequently and were often based on anecdotal remarks. In the past, cultural components were not included as evaluable outcomes within nutrition programs for CVD [58]. A mixed method approach is often suitable for Aboriginal and Torres Strait Islander research, as qualitative feedback can provide valuable insight into the cultural relevance and acceptability of program components [59], factors of which can influence outcome measures. The most recent program in 2014 by Davey and colleagues rated best for overall cultural appropriateness [47] and was the only peer-reviewed program that reported improved quality of life and fatigue levels.
Social determinants are estimated to contribute to over 30% of the health gap between Aboriginal and Torres Strait Islander peoples and non-Indigenous Australians [17]. Those with higher levels of education, income and food security have better health outcomes [60]. Interventions that provided multiple education components that address social determinants were identified to be effective in reducing measures across more than one anthropometric outcome. These educational components increased knowledge and awareness in the areas of healthy eating, weight loss and management, food budgeting, food label reading and the benefits of exercise. Consistent with a holistic health approach, additional education messaging was delivered on health literacy, wellbeing and stress management.
Another key program characteristic that appeared to correspond with improved outcome measures was a longer timeframe designated for interventions. A program that reduced measures in all the anthropometric outcomes of BMI, WC, weight, WHR and fat reduction was delivered over 12 months [50]. Similarly, the two interventions that performed well at reducing measures within multiple biochemical/haematological outcomes were delivered across communities over a longer time-frame of 2 years [46] and 8 years [53]. Emerging evidence suggests that long-term changes in diet quality correlate with a lower risk of CVD and mortality [61]. Interestingly, the three programs that performed well across clinical measures scored 'poor' in the quality appraisal [46,50,53].
Scholarship in the areas of Indigenous epistemology, ontology and axiology has led to an understanding of Aboriginal and Torres Strait Islander ways of knowing as fluid, meaning that it can evolve and are influenced by situational contexts, such as the political and social environment [30,31]. The timeline towards healing and reconciliation, as seen through the social justice report and the Close the Gap and Closing the Gap campaigns have established a discourse amongst academics and researchers to promote Indigenous paradigms in research [14,15,30]. This privileging of Aboriginal and Torres Strait Islander knowledge has led to the development of quality appraisal tools to assess programs not only through a scientific lens but also through an Aboriginal and Torres Strait Islander cultural lens [24].
This review retrospectively assessed the cultural appropriateness of programs and highlighted that of the programs evaluated and peer-reviewed, less than half of the programs answered 'yes' to 50% or more of the quality appraisal questions. As evidenced, most programs performed well at community engagement and capacity strengthening but they lacked the inclusion of Indigenous research paradigms, governance and taking a strengths-based approach. The lack of inclusion of cultural components within the program should be interpreted with consideration that they were reported between 1994 and 2014 and the Aboriginal and Torres Strait Islander QAT used herein was developed in 2018 and published in 2020 [24]. It is possible that the 'poor' QAT score assigned to programs is reflective of the scholarship and understanding in Aboriginal and Torres Strait Islander research at that time. Importantly, this indicates a gap in research and highlights a need for contemporary nutrition programs aimed at improving cardiovascular health outcomes to include additional key cultural components.
An extensive and wide search was a strength of this review, scoping all the available published and unpublished literature. Further, to the author's knowledge, this review was the first to appropriately apply a quality appraisal tool from an Indigenous perspective to ascertain the cultural appropriateness of nutrition programs targeting CVD. A limitation to the review was that only a small number of programs was evaluated, which resulted in limited application of the QAT. Furthermore, this scoping review retrospectively assessed the cultural appropriateness of programs as most peer-reviewed studies retrieved were published between 1994 to 2014, before the development of the QAT in 2018. It is important that the value and relevance of the previous research and programs presented in this review are acknowledged. The findings are not a reflection of overall poor cultural appropriateness, but rather a reflection of the advancement of knowledge in the areas of Indigenous epistemology, ontology, axiology and research methodologies.

Conclusions
Future nutrition programs aiming to improve cardiovascular health outcomes should be multifaceted, incorporating both nutrition and physical activity. Most programs identified in this review undertook community consultation, engagement and capacity strengthening, but improvements in key areas of Indigenous paradigm, governance and strengthsbased approaches are required. Future research should focus on sustainability within communities through effective co-design with Aboriginal and Torres Strait Islander peoples and communities.