Over the past two decades, the prevalence of many metabolic diseases has increased, presenting a significant global health burden (1, 2). In Aotearoa New Zealand (NZ), cardiovascular disease (CVD) is the leading cause of death, accounting for a third of all deaths annually (3), and approximately 5–6% of the population have type 2 diabetes mellitus (T2DM) (4). Over the past seven decades, mortality rates have been consistently higher for Māori (indigenous people of NZ), than non-Māori. Māori are 2.5 times more likely to have T2DM than non-Māori, and the prevalence of T2DM is the highest for Pacific people in NZ (5). Differences in prevalence and mortality signify the disproportionate and increased burden of cardiometabolic disease on Māori and Pacific peoples (4, 6). Metabolic syndrome (MetS) is a combination of multiple risk factors that increases the risk of CVD and T2DM (1). It is characterised by interconnected factors including hypertension, dyslipidaemia, disordered glucose metabolism, and obesity (2).

Unhealthy dietary habits and physical inactivity are important modifiable contributors to cardiometabolic disease risk worldwide (7, 8). The Mediterranean diet (MedDiet) is a well-studied dietary pattern characterised by an abundance of plant-based foods, olive oil, seafood, wholegrains and poultry, and low to moderate intake of red and processed meats, dairy products, and processed food (9, 10). Meta-analyses of the effects of the MedDiet on the MetS have demonstrated an overall positive impact of the MedDiet in decreasing MetS and its component factors in adults, including decreased blood glucose levels, blood pressure, and improved lipid profile (11), as well as decreasing the risk of overall mortality, CVD, and T2DM (12).

Considering the promise of the MedDiet in addressing MetS, it is of interest to investigate its potential in the New Zealand population. Indeed, the Eating and Activity Guidelines for NZ Adults (13) include the same food groups as the MedDiet, with only slight variations in the recommended proportions of different components (14). Additionally, aspects of the MedDiet align with traditional kai/food types and practices for Māori, such as a diet high in seafood (15), and valuing local, seasonal food, how it is prepared and the social context in which it is consumed (16). However, the 2008 NZ Adult Nutrition Survey reported that the average NZ diet differs significantly from the Eating and Activity Guidelines, and, in turn, a MedDiet. In particular, there was a higher intake of dairy and meat. This likely reflects food choices influenced by NZ’s history as an agricultural nation (17, 18). More recent cross-sectional studies of 908 (14) and 350 (19) NZ adults have demonstrated poor alignment with the MedDiet, indicating a significant shift in food choices will be required if the MedDiet is to be adopted in the NZ population (14, 19). Indeed, challenges exist with the transferability and adoption of the MedDiet to non-Mediterranean populations (20, 21); these include accessing and purchasing MedDiet foods such as olive oil (22), differences in habitual intake (14) and therefore adherence to a different dietary pattern (21), culture, religion, traditional cooking practices, and economic burden (23). Despite this, the MedDiet has been adapted and successfully implemented in different populations, such as in Northern Ireland and Australia, with concomitant improvements in MetS components and markers of cardiovascular risk (20, 24), demonstrating its potential for translation to other non-Mediterranean populations, such as New Zealand (25).

As there are substantial potential health benefits of the MedDiet, adaptation of the MedDiet to the NZ context should be explored, with consideration of the needs of Māori given the health disparities they experience. The He Rourou Whai Painga randomised controlled trial (RCT) aims to evaluate if a MedDiet pattern incorporating high quality NZ foods (“NZMedDiet”) improves a composite assessment of cardiometabolic health, the metabolic syndrome severity score (MetSSS) (26) for individuals identified as being at risk of cardiometabolic disease, in a study sample enriched for Māori. The planned intervention for this RCT is delivery in a household/whānau setting, underpinned by behavioural science. To support adherence to the NZMedDiet, participants will be provided kai/food baskets with high quality NZ foods that align with the NZMedDiet. Transparent documentation of the adaption or interpretation of a dietary pattern within nutrition trials is essential for providing context to observed results. However, the process of designing or adapting dietary patterns, such as the MedDiet, for free-living individuals who participate within trials is seldom reported (25). Consequently, the objective of the study reported here is to document the development of the NZMedDiet and composition of the kai/food baskets used in He Rourou Whai Painga; doing so provides a tangible process for adapting the MedDiet to other non-Mediterranean populations.

The present study aims to:

He Rourou Whai Painga is a multi-centre trial consisting of two RCT phases and a longitudinal cohort study. The recruitment target is 200 participants with a MetSSS greater than 0.35 (26). Additionally, aligned both to the NZ Government’s Vision Mātauranga policy to support research of relevance to Māori and a collective worldview, a whānau-led approach will be taken where up to five members of a household in addition to the index participant will be invited to participate in the intervention. Full details on the trial have been published elsewhere (27). In brief, the first RCT compares the NZMedDiet to usual dietary intake with a primary outcome of the MetSSS 12 weeks after randomisation. For the 12-week intervention, participants will receive kai/food baskets containing ingredients and recipes for main meals and snacks, providing up to 75% of the energy requirements of the household/whānau, as per the protocol (27). Participants will also receive access to web-based nutrition education and opt-in online social support to help them adhere to the NZMedDiet. The second RCT compares the ongoing opt-in online social support, to no online social support with an outcome assessment 12-weeks after the second randomisation. From beginning the dietary intervention, the cohort will be followed for a total of 52 weeks.

A key foundation of this trial, therefore, was the development of the NZMedDiet and composition of the kai/food baskets to be received by all 200 participants and their participating whanau members. The process of developing this dietary pattern and kai/food baskets for He Rourou Whai Painga is outlined in Figure 1. This was overseen by a subgroup (the “NZMedDiet subgroup”) of study researchers consisting of eight NZ registered dietitians, two members of the consumer insights team, and another NZ registered dietitian from a commercial meal kit company. Importantly, Māori researchers were partnered with from the conception of this trial to support Pākehā/non-indigenous researchers with the design and implementation of this trial; this included advice while designing the dietary pattern to ensure its acceptability by Māori.

This study reports the process by which the investigators of He Rourou Whai Painga created the NZ version of the MedDiet, and produced a method to deliver foods to participants and their whānau/households aligning with this dietary pattern to meet 75% of their energy needs. The NZMedDiet was developed by adapting the MedDiet, as defined by the LAS and MEDAS tools, to the NZ context and guidelines. The NZMedDiet criteria were used to guide the development of kai/food baskets, providing participants and household members in He Rourou Whai Painga with an estimated average of 73.5% of energy for 12 weeks. Kai/food baskets include NZMedDiet ingredients for breakfasts, lunches, dinners, and snacks, including 22 products from 42 industry partners.

The premise of promoting consumption of the MedDiet is that it will confer health benefits, such as reduction in CVD risk factors (11, 12). Consequently, the degree of difference between the NZMedDiet and the traditional MedDiet needs to be considered. Although the NZMedDiet does not exactly match any previously defined MedDiet scoring tool, when compared to the eight MedDiet questionnaires reviewed by Chiriacò et al. (28), all food items in the NZMedDiet fall within the identified ranges of existing recommended intakes. This indicates that the NZMedDiet is within the scope of how the MedDiet can plausibly be defined. However, when compared to the PyrMDS, considered the most accurate and reliable tool to estimate MedDiet adherence (28), the NZMedDiet falls just under the recommendations for vegetables (≥400 g/day NZMedDiet versus ≥480 g/day PyrMDS), legumes (210 g/week versus 300 g/week), and nuts (90 g/week versus 30-60 g/day), while recommending more red meat (≤437.5 g/week versus ≤200 g/week), and fewer sweets (≤1 serve/week versus ≤2/week) (28, 41). Additionally, the lifestyle habits of Mediterranean populations, such as physical activity, pattern of meals, and context in which meals are consumed, may act as confounding factors to the observed health benefits (22). However, a particular strength of He Rourou Whai Painga is its whānau/household collective wellbeing approach in recognition that food is largely consumed in a shared environment and it is common for cardiometabolic risk to cluster within a family (42); therefore, dietary interventions that target the wider family may be more likely to be successful compared to those which focus solely on improving the health of an individual. These differences in the NZMedDiet criteria compared to the traditional MedDiet and additional lifestyle considerations will be important to consider when analysing the effect of the NZMedDiet in He Rourou Whai Painga.

Trying to fit a MedDiet-style pattern to the AMDRs proved challenging with the provided kai/food baskets predicted to exceed the desired AMDR for fat (39%) and fall short of that for carbohydrates (44%). This is not surprising given the usual amount of fat in the MedDiet is 30–45% (9, 43). However, the type of fat may be of more importance in this case; the MedDiet typically has a higher ratio of mono- and poly-unsaturated fatty acids to saturated fatty acids which can improve LDL cholesterol levels, contributing to the reduction in CVD risk (44). The NZMedDiet is likely to have a similar ratio, as demonstrated by saturated fat predicted to provide less than 10% of total energy. The AMDR estimates do not account for the extra 25% of energy that participants are responsible for purchasing. Consequently, dietary assessment during the trial will be important to establish the actual macronutrient intake compared to the AMDR. Methods of measuring dietary intake will include the Otago Short Form Food Frequency Questionnaire and 24-h recalls (27).

To establish whether the NZMedDiet confers health benefits similar to the MedDiet it is key that participants are supported to adhere to it and that adherence is measured, as the level of adherence to a dietary pattern impacts the effect size on health outcomes (45, 46). For example, to achieve the desired NZMedDiet participants would ideally supplement the kai/food baskets with more olive oil, fish, vegetables and some bread and cereals, red meat, and dairy products. Given the current dietary pattern of NZ adults, particularly those of Māori and Pacific ethnicity, differs greatly from the MedDiet (14, 47) behavioural support to encourage purchase and consumption of these foods is important. Implementing a Mediterranean diet pattern in a non-Mediterranean country has its challenges, with previous research stating the following barriers to adopting such a diet; stress and work pressure; difficulties purchasing food items; increase in food costs and country-specific culture and climate being non-conducive (48). It will be important to identify specific barriers and effective support strategies relevant to the NZ context, including accounting for food practices (21, 49). To do this, the Behaviour Change Wheel (50) will be used in He Rourou Whai Painga, along with continued partnership with Māori as implemented in the feasibility trial (38). This behaviour change framework has been previously used to successfully develop a peer-support intervention to encourage dietary behaviour change towards a MedDiet in non-Mediterranean adults at high CVD risk (20, 51).

Strengths of this study include that we have clearly defined the recommended number of serves and portion sizes for each food group, enabling adherence to the dietary behaviours required within the NZMedDiet to be assessed, a factor frequently overlooked in dietary intervention trials (52, 53). Additionally, the involvement of Tū Kotahi Māori Asthma and Research Trust enabled the target audience to have a voice in what the kai/food baskets contained, demonstrating how these types of projects can be run in partnership with Māori in the community. Limitations of the design of the kai/food baskets include that they are designed based on fixed whānau/household makeups; three-person and five-person households will receive two-person and four-person kai/food baskets, meaning they are supplied less energy relative to other households of two-, four- and six-persons, to not exceed 75% of energy requirements. Additionally, restricting to six whānau/household members may exclude larger whānau/households from participating. The estimations of energy intake in this article are also limited by using 15 meals from the meal kit home delivery service over the 12 weeks; a greater variety of meals will be provided in the actual study. This estimation cannot be directly extrapolated to a two- or six-person whānau/household as, given the different energy requirements within the described whānau/households, the quantity of products received are not always factors of each other. For instance, a four-person whānau/household does not receive exactly double that of the two-person whānau/household, as its energy requirements are not double considering it factors in a child with lower energy requirements as a member. Again, this reinforces the importance of capturing dietary intake during the trial.

In summary, the MedDiet was able to be adapted to the NZ context for the purpose of He Rourou Whai Painga, along with the development of kai/food baskets containing locally sourced produce. He Rourou Whai Painga will provide valuable insight into the acceptability and effectiveness of this dietary pattern in the NZ population, particularly for Māori who experience a disproportionate and increased burden of CVD. Given the current NZ diet differs largely from the MedDiet, behavioural support and continued partnership with Māori will be important in facilitating adherence to the NZMedDiet.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Ethical approval was granted by the New Zealand Health and Disability Ethics Committee—Northern B branch—reference 2022 FULL 12045 for He Rourou Whai Painga. Consent is not applicable for this aspect of the trial.

Jeremy D. Krebs, Department of Medicine, University of Otago Wellington, Wellington, New Zealand, Centre for Endocrine, Diabetes and Obesity Research (CEDOR), Wellington Regional Hospital –Te Whatu Ora, Wellington New Zealand, Principal investigator; Richard Gearry, Department of Medicine, University of Otago Christchurch, Christchurch, New Zealand; Troy L. Merry, Discipline of Nutrition, School of Medical Sciences, The University of Auckland, Auckland, New Zealand, Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand; Andrea Braakhuis, Discipline of Nutrition, School of Medical Sciences, The University of Auckland, Auckland, New Zealand; Fiona Lithander, Discipline of Nutrition, School of Medical Sciences, The University of Auckland, Auckland, New Zealand, Liggins Institute, The University of Auckland, Auckland, New Zealand; Meika Foster, Liggins Institute, The University of Auckland, Auckland, New Zealand, Edible Research Ltd, Ohoka, New Zealand; Anna Rolleston, Manawaora Integrated Health and Research Ltd, Tauranga, New Zealand; Amber Parry-Strong, Centre for Endocrine, Diabetes and Obesity Research (CEDOR), Wellington Regional Hospital–Te Whatu Ora, Wellington New Zealand; Cecilia Ross, Centre for Endocrine, Diabetes and Obesity Research (CEDOR), Wellington Regional Hospital –Te Whatu Ora, Wellington New Zealand; Mark Weatherall, Department of Medicine, University of Otago Wellington, Wellington, New Zealand; Denise Conroy, Plant and Food Research, Auckland, New Zealand; Cheryl Davies, Tū Kotahi Māori Asthma and Research Trust, Kōkiri Marae, Lower Hutt, New Zealand; Anna Worthington, 4 Discipline of Nutrition, School of Medical Sciences, The University of Auckland, Auckland, New Zealand.

AW: Conceptualization, Data curation, Formal analysis, Methodology, Writing – original draft, Writing – review & editing. EL: Writing – original draft, Writing – review & editing. MF: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Supervision, Writing – review & editing. SW: Data curation, Formal analysis, Methodology, Validation, Writing – review & editing. FL: Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Writing – review & editing. CW: Formal analysis, Supervision, Writing – review & editing. RR: Data curation, Formal analysis, Writing – review & editing. AP-S: Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Writing – review & editing. JK: Conceptualization, Funding acquisition, Supervision, Writing – original draft, Writing – review & editing. AB: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Supervision, Validation, Writing – original draft, Writing – review & editing.