Development, validation, and use of a semi-quantitative food frequency questionnaire for assessing protein intake in Papua New Guinean Highlanders

What Do We Know about the Diets of Pacific Islander Adults in Papua New Guinea? A Scoping Review

While a large proportion of the population in Papua New Guinea (PNG) maintain a subsistence lifestyle, exposure to modernisation and industrialisation since European contact has influenced a transition towards Western diets. This review aimed to scope and summarise the published research on dietary intake among Pacific Islander adults in PNG. Four electronic databases and grey literature were searched. Two reviewers completed the screening and data extraction. Fourteen studies were included from the Highlands (n = 7), Southern (n = 5), Momase (n = 1) and both the Highlands/Southern region (n = 1). No studies were from the Islands region. The majority of the studies were published prior to the year 2000 (n = 9). Geographical region and degree of urbanisation had an impact on dietary intake. Urban areas reported higher intakes of energy, protein and fat compared to rural areas. In the Southern region, a variety of foods, including sago, taro, kaukau, cooked banana, coconut and cassava contributed to energy intake, while kaukau was the main energy and protein source in the Highlands. The main foods contributing to protein in the Southern region were fresh fish, land animals and purchased animals. This review highlights an evidence gap regarding dietary intake research. Within the context of international initiatives, there is an urgent call for research aimed at understanding the social and cultural contextualisation of dietary behaviours in PNG.

Carbon and nitrogen stable isotope ratios of diet of the Japanese and diet-hair offset values

The stable isotope ratios of carbon and nitrogen (δ¹³C and δ¹⁵N) were measured in composite samples of Japanese food and hair. Three hundred eighty-nine foodstuffs were collected in Tokyo and Gunma Prefecture, Japan, in 2020. The foodstuffs were classified into 15 food categories, prepared as usually consumed, and mixed to make 15 composite samples representing each of the food categories. Similarly prepared samples for foodstuffs collected in 2011 and 2015 were also examined. Composite hair samples were collected from a barber shop in Tokyo and a beauty salon in Gunma in 2019. The δ¹³C and δ¹⁵N values of the food and hair composites were measured by elemental analyzer/isotope ratio mass spectrometry after defatting. The δ¹³C and δ¹⁵N values of the food composite varied from composite to composite and according to year of collection. The whole-diet δ¹³C values were -21.1, -22.0, and -21.5 ‰ for the 2011, 2015, and 2020 samples, respectively; the δ¹⁵N values were 5.0, 4.4, and 4.4 ‰, respectively. Diet-hair offset values of δ¹³C and δ¹⁵N were calculated to be 1.9 and 4.3 ‰ for δ¹³C and δ¹⁵N, respectively. These offset values will be important for dietary analysis and nutritional research using hair isotope ratios.

Gut microbiota composition in obese and non-obese adult relatives from the highlands of Papua New Guinea

Obesity is a condition that results from an imbalance between energy intake and expenditure. Recently, obesity has been linked to differences in the composition of gut microbiota. To examine this association in Papua New Guinea (PNG) highlanders, fecal samples were collected from 18 adults; nine obese participants were paired with their non-obese relative. Amplification of the 16S rRNA gene targeting the V1-V2 region was performed on DNA extracts for each participant, with high-quality sequences selected and used for operational taxonomic unit clustering. The data showed Firmicutes and Bacteroidetes were the two dominant phyla, while at genus level Prevotella was the most dominant genus in all of the samples. Nonetheless, statistical evaluation of potential association between nutritional status and bacterial abundance at both phyla and genus levels showed no significant difference. Further studies, ideally in both rural and urban areas, are needed to evaluate the role of the gut microbiome in the occurrence of obesity in PNG and other resource-limited settings.

A culture-sensitive semi-quantitative FFQ for use among the adult population in Nairobi, Kenya: development, validity and reproducibility

OBJECTIVE

To develop a semi-quantitative FFQ and to evaluate its validity and reproducibility for the assessment of total dietary intake of Kenyan urban adult population, given its non-existence in Kenya.

DESIGN

The current study adopted a cross-sectional design. A culture-sensitive semi-quantitative FFQ was developed and its validity was tested relative to three non-consecutive 24-h recalls (24hR). Reproducibility was tested by the test-retest method, with a 3-week interval. Spearman's correlation coefficients and intra-class correlation coefficients were calculated for several macro- and micronutrients. Cross-classification into quartiles and Bland and Altman plots were analysed.

SETTING

Nairobi county (Dagoreti South and Starehe constituencies).

PARTICIPANTS

A convenient sample was recruited in three different clusters in Nairobi.

RESULTS

A culture-sensitive 123-food-item semi-quantitative FFQ showed higher nutrient intakes compared with the 24hR (total energy median 12543·632 v. 8501·888 kJ, P < 0·001). Energy-adjusted and deattenuated Spearman's correlations for macronutrients ranged between 0·21 (total fat) and 0·47 (protein). The agreement in the same quartile varied from 28 % (protein) to 41 % (carbohydrates). Including adjacent quartiles, the range increased: 76 % (protein and fat) to 81 % (carbohydrates). The extreme disagreement was low. The first FFQ application resulted in higher mean values for all nutrients compared with the second FFQ (total energy median 12459·952 v. 10485·104 kJ, P < 0·001). Energy-adjusted correlations for macronutrients ranged from 0·28 (carbohydrates) to 0·61 (protein). Intra-class correlation coefficients for macronutrients were moderate, between 0·6 and 0·7.

CONCLUSIONS

The developed semi-quantitative FFQ was shown to be a valid and reproducible tool for ranking urban adult Kenyans according to their dietary intake.

Health Challenges of the Pacific Region: Insights From History, Geography, Social Determinants, Genetics, and the Microbiome

The Pacific region, also referred to as Oceania, is a geographically widespread region populated by people of diverse cultures and ethnicities. Indigenous people in the region (Melanesians, Polynesians, Micronesians, Papuans, and Indigenous Australians) are over-represented on national, regional, and global scales for the burden of infectious and non-communicable diseases. Although social and environmental factors such as poverty, education, and access to health-care are assumed to be major drivers of this disease burden, there is also developing evidence that genetic and microbiotic factors should also be considered. To date, studies investigating genetic and/or microbiotic links with vulnerabilities to infectious and non-communicable diseases have mostly focused on populations in Europe, Asia, and USA, with uncertain associations for other populations such as indigenous communities in Oceania. Recent developments in personalized medicine have shown that identifying ethnicity-linked genetic vulnerabilities can be important for medical management. Although our understanding of the impacts of the gut microbiome on health is still in the early stages, it is likely that equivalent vulnerabilities will also be identified through the interaction between gut microbiome composition and function with pathogens and the host immune system. As rapid economic, dietary, and cultural changes occur throughout Oceania it becomes increasingly important that further research is conducted within indigenous populations to address the double burden of high rates of infectious diseases and rapidly rising non-communicable diseases so that comprehensive development goals can be planned. In this article, we review the current knowledge on the impact of nutrition, genetics, and the gut microbiome on infectious diseases in indigenous people of the Pacific region.

A High Burden of Asymptomatic Gastrointestinal Infections in Traditional Communities in Papua New Guinea

Stool samples were collected from 148 healthy adults living a traditional subsistence lifestyle in Papua New Guinea and screened for enteric pathogens using real-time RT-PCR/PCR assays. Enteric pathogens were detected in a high proportion (41%) of individuals. Clear differences were observed in the detection of pathogens between highland and lowland communities. In particular, there was a marked difference in detection rates of norovirus GII (20% and 0%, respectively) and Shigella sp. (15% and 0%, respectively). Analysis of the relationship between enteric pathogen carriage and microbial community composition of participants, using box plots to compare specific normal flora population numbers, did not suggest that gut microbial composition was directly associated with pathogen carriage. This study suggests that enteric pathogens are common in healthy individuals in Papua New Guinean highland communities, presumably acting as a reservoir of infection and thus contributing to a high burden of gastrointestinal illnesses.

Development and Validation of a Mediterranean Oriented Culture-Specific Semi-Quantitative Food Frequency Questionnaire

The objectives were to develop a Mediterranean oriented semi-quantitative food frequency questionnaire (FFQ) and evaluate its validity in measuring energy and nutrient intakes. For FFQ development, the main challenge was to merge food items and practices reflecting cultural Mediterranean preferences with other food choices ensuing from diet transition to more westernized dietary patterns. FFQ validity was evaluated by comparing nutrient intakes against the average of two 24-h dietary recalls for 179 pregnant women. Although the mean intake values for most nutrients and energy tended to be higher when determined by the FFQ, the Cohen's d was below 0.3. Bland-Altman plots confirmed the agreement between the two methods. Positive significant correlations ranged from 0.35 to 0.77. The proportion of women classified correctly was between 73.2% and 92.2%, whereas gross misclassification was low. Weighted kappa values were between 0.31 and 0.78, while intraclass correlation coefficients were between 0.49 and 0.89. Our methodological approach for the development and validation of this FFQ provides reliable measurements of energy, macro- and micronutrient intakes. Overall, our culture-specific FFQ could serve as a useful assessment tool in studies aiming at monitoring dietary intakes, especially in the Mediterranean region, where countries share common cultural dietary habits.

Nitrogen fixation and nifH diversity in human gut microbiota

It has been hypothesized that nitrogen fixation occurs in the human gut. However, whether the gut microbiota truly has this potential remains unclear. We investigated the nitrogen-fixing activity and diversity of the nitrogenase reductase (NifH) genes in the faecal microbiota of humans, focusing on Papua New Guinean and Japanese individuals with low to high habitual nitrogen intake. A ¹⁵N₂ incorporation assay showed significant enrichment of ¹⁵N in all faecal samples, irrespective of the host nitrogen intake, which was also supported by an acetylene reduction assay. The fixed nitrogen corresponded to 0.01% of the standard nitrogen requirement for humans, although our data implied that the contribution in the gut in vivo might be higher than this value. The nifH genes recovered in cloning and metagenomic analyses were classified in two clusters: one comprising sequences almost identical to Klebsiella sequences and the other related to sequences of Clostridiales members. These results are consistent with an analysis of databases of faecal metagenomes from other human populations. Collectively, the human gut microbiota has a potential for nitrogen fixation, which may be attributable to Klebsiella and Clostridiales strains, although no evidence was found that the nitrogen-fixing activity substantially contributes to the host nitrogen balance.

Characterization of the gut microbiota of Papua New Guineans using reverse transcription quantitative PCR

There has been considerable interest in composition of gut microbiota in recent years, leading to a better understanding of the role the gut microbiota plays in health and disease. Most studies have been limited in their geographical and socioeconomic diversity to high-income settings, and have been conducted using small sample sizes. To date, few analyses have been conducted in low-income settings, where a better understanding of the gut microbiome could lead to the greatest return in terms of health benefits. Here, we have used quantitative real-time polymerase chain reaction targeting dominant and sub-dominant groups of microorganisms associated with human gut microbiome in 115 people living a subsistence lifestyle in rural areas of Papua New Guinea. Quantification of Clostridium coccoides group, C. leptum subgroup, C. perfringens, Bacteroides fragilis group, Bifidobacterium, Atopobium cluster, Prevotella, Enterobacteriaceae, Enterococcus, Staphylococcus, and Lactobacillus spp. was conducted. Principle coordinates analysis (PCoA) revealed two dimensions with Prevotella, clostridia, Atopobium, Enterobacteriaceae, Enterococcus and Staphylococcus grouping in one dimension, while B. fragilis, Bifidobacterium and Lactobacillus grouping in the second dimension. Highland people had higher numbers of most groups of bacteria detected, and this is likely a key factor for the differences revealed by PCoA between highland and lowland study participants. Age and sex were not major determinants in microbial population composition. The study demonstrates a gut microbial composition with some similarities to those observed in other low-income settings where traditional diets are consumed, which have previously been suggested to favor energy extraction from a carbohydrate rich diet.