Discussion

The current systematic review found that while dietary data were available on fat, sugar and salt intakes in Pacific Island countries, some countries had limited or no data, and most countries lacked high-quality data. In fact, only Fiji has a recent comprehensive nutrition survey. The absence of quality nutrition data is concerning, given high rates of NCD in the region^{( 1 )} and changing dietary patterns from traditional diets toward a more Western-style diet as shown by historical trends from previous studies⁽ Reference Thow, Heywood and Schultz ^{4 ,} Reference Charlton, Russell and Gorman ^{6 )}. Furthermore, changes in local food production, population growth, environmental conditions, increased reliance on processed and imported foods, and lack of policies⁽ Reference Iese, Paeniu and Pouvalu ^{12 ,} Reference Snowdon, Raj and Reeve ^{48 )} also put Pacific Islanders at a higher risk for NCD. There is a need for better data on Pacific diets to establish benchmark consumption levels, to better inform initiatives to improve diets. Also, quality parameters should be considered when interpreting existing data.

The percentage contribution to total energy intake from fat was below the recommended 30–35 % of total energy^{( 49 )} for four countries, although in the case of Solomon Islands⁽ Reference Tsuchiya, Tagini and Cafa ^{38 )} energy from fat was at the minimum level of 15 % recommended for adequate population consumption of energy^{( 49 )}. Furthermore, it is important to note that absolute intake of total fat was about 100 g/d in Fiji, Guam and Tonga, similar to intakes reported in developed countries^{( 50 )}. In terms of saturated fat intake, the modelling study by Micha et al.⁽ Reference Micha, Khatibzadeh and Shi ^{46 )} showed that the nine Pacific Island countries with data had the highest intakes of this nutrient (average of 23·5 %), far exceeding the recommended limit of <10 % of total energy^{( 49 )} and the global average of 9·4 %. A review of data from forty countries in 2013 found that total fat intake is correlated with saturated fat intake, but not with polyunsaturated fat intake⁽ Reference Harika, Eilander and Alssema ^{51 )}. This suggests that interventions aimed at lowering fat intake should focus not only on lowering saturated fat intake, but also increasing polyunsaturated fat intake⁽ Reference Harika, Eilander and Alssema ^{51 ,} Reference Jakobsen, O’Reilly and Heitmann ^{52 )}.

There was not enough information about absolute intake of sugar, although based on household expenditure and percentage contribution to energy intake data it appeared that Kiribati had high sugar intakes relative to other Pacific Island countries. Unfortunately, there was no information available about sources of sugar or consumption patterns to further explain this finding, although an earlier study reported that sugar-sweetened beverage consumption in Kiribati was moderate (less than 23 % of 11- to 18-year-olds consuming soft drinks daily and import of less than 40 litres per person⁽ Reference McDonald ^{8 )}).

All countries with data appeared to be exceeding the WHO recommended limit of less than 5 g salt/person per day, contributing to the high rates of morbidity and mortality due to CVD⁽ Reference Strazzullo, D’Elia and Kandala ^{53 )}. As such, salt reduction initiatives and policies are essential to lower population salt intake and reduce the burden of NCD^{( 54 )}. A systematic review of salt reduction initiatives around the world in 2015 reported that only a few Pacific Island countries engage in actions to reduce salt intake (e.g. food reformulation and front-of-pack labelling)⁽ Reference Trieu, Neal and Hawkes ^{55 )}, and a separate review showed that while there has been good progress in terms of planning strategies, barriers such as the lack of capacity to accurately measure salt intake and effectively implement activities hinder further progress⁽ Reference Christoforou, Snowdon and Laesango ^{56 )}. The population-based multisectoral salt reduction interventions implemented in Fiji⁽ Reference Pillay, Trieu and Santos ^{34 )} and Samoa⁽ Reference Trieu, Ieremia and Santos ^{36 )} both showed a non-significant change in salt intake following the interventions. The authors identified reasons for the null effect such as the short intervention duration (18 months), low intervention dose, lack of participation from other government sectors and limited engagement with the food industry. These suggest the need for stronger and more active mechanisms for multisectoral governance and partnership; engaging with the food industry; and planning, monitoring and evaluation of interventions to reduce salt intake in the region.

Although not specifically covered in the present review, a common theme noted in the identified studies was the increasing reliance of Pacific Islanders on processed foods. This was evident in countries with data on main sources and behaviours, which showed that the consumption of these foods (e.g. canned meat and fish, rice, sugar-sweetened drinks and instant noodles, among others) was frequent and common. This trend may also be reflected at feasts. Paulino et al.⁽ Reference Paulino, Leon Guerrero and Novotny ^{19 )} found that the type of foods served during feast days in Guam has shifted from low-energy foods to predominantly high-energy foods such as ‘meats, desserts, sodas and other sweetened beverages’. Further studies are warranted to confirm this in other countries. A review of processed foods in Pacific Island countries reported that most are heavily dependent upon food imports with only a small proportion of foods produced locally⁽ Reference Snowdon, Raj and Reeve ^{48 )}. Previous studies have shown that an increasing reliance on energy-dense nutrient-poor imported foods is associated with increases in NCD⁽ Reference Hughes and Lawrence ^{15 ,} Reference Ulijaszek ^{57 ,} Reference Brownell and Yach ^{58 )}. This demonstrates the wide scope for potential strategies including regulations on imported products, food safety and labelling in the Pacific Islands⁽ Reference Snowdon, Raj and Reeve ^{48 , 59 )}.

The current review revealed a range of different dietary assessment methods employed by studies. This variation limits comparison of intakes between countries and over time within a country. Data were available from HIES however, including in five countries where HIES was the only source of nutrition data. In the absence of other national surveys using standardized methodologies, these surveys may provide a good proxy measure of dietary intake⁽ Reference Smith, Dupriez and Troubat ^{60 )}. If HIES are used in this manner, standardization and reporting of methods may need to be strengthened as most reports did not provide information on standardization methods. We also observed country differences in the way foods were grouped and reported which made them unsuitable for comparison. For instance, sugar intake was reported as sugar alone or confectionery alone, sugar and confectionery combined, or sugar, jam, honey, chocolate and confectionery.

Differences in quality between peer-reviewed studies and grey literature studies were observed. Peer-reviewed studies generally used direct approaches to measuring diet but had poor participation rates, while grey literature studies, which were generally reports of national surveys, had better participation rates but often employed indirect approaches to measure dietary intake. Furthermore, grey literature studies were larger scale (national) compared with peer-reviewed studies which were usually implemented at a community or village level. This suggests that strengthening the quality of nutrition data in the Pacific will require the use of more direct dietary methods in national surveys and efforts to link large- and small-scale studies. This was achieved in Samoa⁽ Reference Webster, Su’a and Ieremia ^{37 )} where 24 h urine collection was measured from a subset of STEPS participants (i.e. targeted 500 individuals out of 2800 STEPS participants) and demonstrated that it was feasible to incorporate salt intake measurements into a population-based national survey without large additional costs. This is important since the WHO has recommended the integration of salt intake monitoring through urine collection into its STEPS surveys^{( 47 )}.

Strengths of the present review include the systematic approach, the breadth of databases searched, multiple search strategies and extensive grey literature searches, and stakeholder input. All Pacific Island countries were individually searched within the published literature. Quality assessment was conducted at the dietary assessment and study methodology level, which, to the authors’ knowledge, has not been done before in a review of dietary intakes of Pacific Island countries. Limitations of the review include the restriction by language and publication date. Given several of the countries included are French-speaking and that all Pacific Island countries have English as a second language, it is likely that nutrition data are reported in other languages that we have missed. Synthesis was also only based on studies that collected data in 2005 and thereafter, and a meta-analysis would have strengthened the analysis but was deemed inappropriate due to the heterogeneity across the studies. Within each type of outcome, it was also not possible to pool the results due to different assessment methods and analytical approaches. The review also focused on adults only. A number of Pacific countries are implementing health promotion programmes in schools, so a similar review of children and adolescents may be helpful.