Unravelling the determinants of human health in French Polynesia: the MATAEA project.

Background: French Polynesia is a French overseas collectivity in the Southeast Pacific, comprising 75 inhabited islands across five archipelagoes. The human settlement of the region corresponds to the last massive migration of humans to empty territories, but its timeline is still debated. Despite their recent population history and geographical isolation, inhabitants of French Polynesia experience health issues similar to those of continental countries. Modern lifestyles and increased longevity have led to a rise in non-communicable diseases (NCDs) such as obesity, diabetes, hypertension, and cardiovascular diseases. Likewise, international trade and people mobility have caused the emergence of communicable diseases (CDs) including mosquito-borne and respiratory diseases. Additionally, chronic pathologies including acute rheumatic fever, liver diseases, and ciguatera, are highly prevalent in French Polynesia. However, data on such diseases are scarce and not representative of the geographic fragmentation of the population. Objectives: The present project aims to estimate the prevalence of several NCDs and CDs in the population of the five archipelagoes, and identify associated risk factors. Moreover, genetic analyses will contribute to determine the sequence and timings of the peopling history of French Polynesia, and identify causal links between past genetic adaptation to island environments, and present-day susceptibility to certain diseases. Methods: This cross-sectional survey is based on the random selection of 2,100 adults aged 18-69 years and residing on 18 islands from the five archipelagoes. Each participant answered a questionnaire on a wide range of topics (including demographic characteristics, lifestyle habits and medical history), underwent physical measurements (height, weight, waist circumference, arterial pressure, and skin pigmentation), and provided biological samples (blood, saliva, and stool) for biological, genetic and microbiological analyses. Conclusion: For the first time in French Polynesia, the present project allows to collect a wide range of data to explore the existence of indicators and/or risk factors for multiple pathologies of public health concern. The results will help health authorities to adapt actions and preventive measures aimed at reducing the incidence of NCDs and CDs. Moreover, the new genomic data generated in this study, combined with anthropological data, will increase our understanding of the peopling history of French Polynesia. Clinical trial registration: https://clinicaltrials.gov/, identifier: NCT06133400.

Branched-Chain and Aromatic Amino Acids in Relation to Fat Mass and Fat-Free Mass Changes among Adolescents: A School-Based Intervention.

Plasma levels of branched-chain amino acids (BCAA) and aromatic amino acids (AAA) are considered early metabolic markers of obesity and insulin resistance (IR). This study aimed to assess changes in plasma concentrations of BCAA/AAA and HOMA-IR2 (homeostasis model assessment of IR) after intervention-induced modifications in fat mass (FM) and fat-free mass (FFM) among French Polynesian adolescents. FM, FFM, plasma levels of BCAA and AAA, HOMA-IR2 were recorded at baseline and post intervention among 226 adolescents during a 5-month school-based intervention on diet and physical activity. Participants were divided into two subgroups according to their college attendance status which determined their intervention adherence: externs/half-residents (n = 157) and residents (n = 69). Four ordinal categories of body composition changes post-intervention were created for the analysis (FMgain/FFMlost < FMgain/FFMgain < FMlost/FFMlost < FMlost/FFMgain). After 5 months, changes in BCAA (p−trend < 0.001) and AAA (p−trend = 0.007) concentrations were positively associated with ordinal categories of body composition. HOMA-IR2 significantly decreased with FMlost (−0.40; 95% CI, −0.60 to −0.20) and increased with FMgain (0.23; 95% CI, 0.11 to 0.36). Our results suggest that FM loss is associated with a decrease in concentrations of obesity and IR metabolic markers which is more substantial when FM loss is accompanied with FFM gain.

Exposure to toxic metals and polychlorinated biphenyls of adolescents and adults from two atolls in the Tuamotu Archipelago (French Polynesia).

The atoll of Hao, part of the Tuamotu Archipelago in French Polynesia, hosted an air base which was used by France Air Force and Naval Aviation during the nuclear tests. Following the publication of a report in 2012 indicating widespread contamination of the atoll, we conducted a biomonitoring survey to assess the exposure to toxic metals and polychlorinated biphenyls (PCBs) of Hao residents and residents of Makemo, a nearby atoll without any known sources of industrial pollution. Adults and adolescents (≥12 years) randomly sampled from Hao (n = 275) and Makemo (n = 268) provided blood samples for contaminant analyses. Whole blood samples were analysed for cadmium, lead and total mercury by inductively coupled plasma mass spectrometry. Plasma concentrations of PCBs were measured by gas chromatography mass spectrometry. Face-to-face interviews were conducted to document lifestyle and a food-frequency questionnaire was used to document dietary habits. Concentrations of contaminants were compared between atolls and associations with sociodemographic and personal characteristics of the participants were investigated. A significantly higher mean (geometric) of blood lead concentration was observed in Hao compared to Makemo (3.75 vs 3.40 µg/L, P = 0.02), whereas similar concentrations were noted for cadmium (0.49 vs 0.50 µg/L, P = 0.58) and mercury (11.4 vs 11.5 µg/L, P = 0.78). Mean total PCBs plasma concentration was significantly higher in Hao than in Makemo participants (0.75 vs 0.32 µg/L, P < 0.001). A significant proportion of participants exceeded toxicological reference values for mercury and lead in both atolls. The higher body burden of PCBs and Pb in Hao compared to Makemo residents may be linked to past air base activities in Hao. According to international standards, PCBs exposure is low; however, exposure to both mercury and lead is high and further investigations are required to identify specific sources of exposure.

Obesity and metabolic parameters in adolescents: a school-based intervention program in French Polynesia.

PURPOSE: The prevalence of overweight/obesity among French Polynesian adolescents is alarming. This study aims to prevent rises in obesity by modifying school food and the physical environment of French Polynesian adolescents. METHODS: During the 5-month study, 240 adolescents from a Tubuai island college (in French Polynesia) received a balanced diet based almost exclusively on local agricultural products and fishing by the island community. They were divided into three subgroups according to their college attendance status: external (n = 14), half residents (n = 155), and residents (n = 71). To increase energy expenditure, weekly physical activity was augmented by 2-4 hours of training in Polynesian Va'a canoes. Anthropometric parameters were recorded, and blood samples collected at baseline and after 5 months. Collegians from Rurutu, a neighboring island, were considered as controls (N = 90). RESULTS: At baseline, overweight/obesity prevalence was 60% (with 28% obesity) in the intervention group. After 5 months, adjusted weight gain was -.76 kg for residents (95% confidence interval [CI], -1.59 to .08), 1.34 kg for half residents (95% CI, .84-1.83), 1.82 kg for externs (95% CI, .66-2.97), and 4.2 kg (95% CI, 3.4-5.0) in the controls. Our results indicate that the more adolescents were subjected to food and physical activity commitments, the higher was the rate among those who lost weight. We noted that the weight change magnitude predicted insulin, glucose, and visceral obesity modifications. CONCLUSIONS: This 5-month school-based intervention slowed weight gain and improved the health of Polynesian collegians. The implementation of longer school-based interventions deserves evaluation.

Influence of polyunsaturated fatty acids on blood pressure, resting heart rate and heart rate variability among French Polynesians.

OBJECTIVE: To analyze the associations between marine n-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP), resting heart rate (HR), and heart rate variability (HRV) in a population highly exposed to methylmercury through the diet. METHODS: Concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in erythrocytes membranes were measured in 180 French Polynesian adults (≥18 years) residing in Tubuai, which is a community with a traditional lifestyle, or Papeete, which has a modern lifestyle. HRV was measured using a 2-hour ambulatory electrocardiogram (Holter). Resting HR and BP were measured using standardized protocols and pulse pressure (PP) was calculated as systolic BP - diastolic BP. The associations between n-3 PUFAs and the dependent variables were studied using simple and multiple linear regressions. RESULTS: Increasing DHA concentration was associated with lower resting HR (ß = -2.57, p = 0.005) and diastolic BP (ß = -1.96, p = 0.05) and higher HRV in multivariable models. Specifically, DHA was associated with high frequency (HF; ß = 0.19, p = 0.02) and the square root of the mean squared differences of successive R-R intervals (difference between two consecutive R waves; rMSSD; ß = 0.08, p = 0.03), which are specific indices of the parasympathetic activity of the autonomic nervous system. CONCLUSION: DHA was associated with lower BP and resting HR and higher HRV among French Polynesians who are also exposed to high methylmercury levels.

Influence of mercury exposure on blood pressure, resting heart rate and heart rate variability in French Polynesians: a cross-sectional study.

BACKGROUND: Populations which diet is rich in seafood are highly exposed to contaminants such as mercury, which could affect cardiovascular risk factors OBJECTIVE: To assess the associations between mercury and blood pressure (BP), resting heart rate (HR) and HR variability (HRV) among French Polynesians METHODS: Data were collected among 180 adults (≥ 18 years) and 101 teenagers (12-17 years). HRV was measured using a two-hour ambulatory electrocardiogram (Holter) and BP was measured using a standardized protocol. The association between mercury and HRV and BP parameters was studied using analysis of variance (ANOVA) and analysis of covariance (ANCOVA) RESULTS: Among teenagers, the high frequency (HF) decreased between the 2nd and 3rd tertile (380 vs. 204 ms2, p = 0.03) and a similar pattern was observed for the square root of the mean squared differences of successive R-R intervals (rMSSD) (43 vs. 30 ms, p = 0.005) after adjusting for confounders. In addition, the ratio low/high frequency (LF/HF) increased between the 2nd and 3rd tertile (2.3 vs. 3.0, p = 0.04). Among adults, the standard deviation of R-R intervals (SDNN) tended to decrease between the 1st and 2nd tertile (84 vs. 75 ms, p = 0.069) after adjusting for confounders. Furthermore, diastolic BP tended to increase between the 2nd and 3rd tertile (86 vs. 91 mm Hg, p = 0.09). No significant difference was observed in resting HR or pulse pressure (PP) CONCLUSIONS: Mercury was associated with decreased HRV among French Polynesian teenagers while no significant association was observed with resting HR, BP, or PP among teenagers or adults.

High fish consumption in French Polynesia and prenatal exposure to metals and nutrients.

French Polynesians consume high quantities of fish and are therefore exposed to seafood-related contaminants such as mercury (Hg) or lead (Pb) and nutrients such as iodine, selenium and long chain polyunsaturated fatty acids (LC-PUFAs). As the developing foetus is sensitive to contaminants and nutrients, a cross-sectional study was conducted in French Polynesia in 2005-2006 to assess prenatal exposure to contaminants and nutrients through fish consumption. Two hundred and forty one (241) delivering women originating from all islands of French Polynesia were recruited and agreed to answer questions on fish consumption and gave permission to collect umbilical cord blood for metals and nutrients analyses. All parameters were found in high concentrations in cord blood samples except for lead. Mercury concentrations averaged 64.6 nmol/L (or 13 microg/L) with values ranging from 0.25 to 240 nmol/L. Of the sample, 82.5% had Hg concentrations above the US-EPA blood guide-line of 5.8 microg/L. Tuna was the fish species which contributed the most to Hg exposure. High selenium and LC-PUFAs may counterbalance the potential risk of prenatal exposure to Hg in French Polynesia. Due to the high fish consumption of mothers, Polynesian newborns are prenatally exposed to high doses of mercury. Although selenium and omega-3 fatty acids may counteract mercury toxicity, informing pregnant women on both the mercury and nutrient content of local fish species is important.

Fish consumption and health in French Polynesia.

French Polynesians, like other remote maritime populations are intimately connected to the ocean which nourishes their daily life and culture. Their reliance on fish raises the issue of potential exposure to harmful natural and anthropogenic contaminants as well as providing essential nutrients. The purpose of this study was to assess the risks and benefits of fish consumption in French Polynesia. This cross-sectional study included 195 adults aged 18 years old and over from the Tahiti and Moorea islands. Fatty acids, selenium (Se) and mercury (Hg) blood concentrations were measured in participants and were all very high. Blood concentrations indicate that Hg, Se and omega-3 fatty acids have a common origin, i.e. fish consumption. In comparing the Polynesian group with northern populations, we found that the Polynesian group had levels of Hg similar to those observed in Inuit populations (geometric mean (range): 90.3 (15-420) nmol/L vs. Inuit: m(r): 79.6 (4-560) nmol/L). Similar results were observed with Se blood concentrations. The fatty acid concentration was also similar to that of the Inuit population even though the specific profile of fatty acids differed. For the first time, we report very high blood concentrations of mercury, selenium and omega-3 fatty acids in a fishing population from the South Pacific, comparable to those reported among fishing populations from the Northern hemisphere. Further work is ongoing to better substantiate public health nutritional policies.