Environmental impacts of food systems have stimulated research to examine how to create healthy diets that will be more sustainable while meeting nutrient requirements. Increasing compliance with existing food-based dietary guidelines in most jurisdictions could be a first step to improve health and reduce environmental impact. MyPlanetDiet was an all-Ireland 12-week randomised controlled trial designed to inform sustainable healthy dietary guidelines. Healthy adults (n 355) aged 18–64 years with moderate-to-high greenhouse gas emitting (GHGE) diets were recruited from three study sites on the island of Ireland. The aim of this research is to assess the relationship between dietary intakes, diet-related environmental impacts and metabolic health using baseline data collected during the MyPlanetDiet study. Dietary assessments collected using Foodbook24 were used to calculate diet-related GHGE, adherence to healthy eating guidelines (HEG) and healthy eating index (HEI) score. Anthropometrics and metabolic health markers (e.g. lipids, glucose and insulin) were included. Overall HEG adherence was low, with 43 % meeting zero or one HEG food group recommendations. Adherence to 4 + HEG food group targets was associated with 31 % lower diet-related GHGE compared with those with lowest adherence. Higher HEG adherence was associated with lower BMI and waist circumference and higher HEI scores. While our findings suggest HEG adherence is associated with positive health and environmental impacts, substantial behaviour change will be needed to meet existing HEG. Further research is needed to assess response and acceptability to HEG. However, adherence to HEG may be an important first step to reducing the environmental impact of food consumption.

This abstract was presented as the Nutrition and Optimum Life Course Theme Highlight.

The n-3 polyunsaturated fatty acids (n-3 PUFA), eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), are known for their beneficial roles in regulating inflammation(1). The omega 3 index (O3I) refers to the percentage of EPA+DHA within the erythrocyte membrane with respect to total fatty acids and is a recognised biomarker for cardiovascular disease(2). An O3I >8% is proposed to confer the greatest level of cardioprotection(2). Fish is the richest dietary source of n-3 PUFAs and has been noted as one of the main predictors of a higher O3I(3). Current UK dietary guidelines recommend the consumption of two portions of fish per week; albeit the efficacy of these recommendations in raising the O3I is unknown(4). The aim of this study was to investigate the influence of consuming two portions of fish per week on the O3I amongst low fish consuming women of childbearing age.

Data were analysed from the iFish study(5), an 8-week randomised controlled trial where low fish consuming women, were randomly assigned to consume either no fish (n = 18) or 2 portions of tuna (n = 8) or sardines (n = 9) per week. Total n-3 PUFA concentrations of the fish provided in the intervention were 6.47g/100g for sardines and 4.57g/100g for tuna. Fasting blood samples were collected at baseline and post-intervention. The O3I was determined in red blood cells in the control and two portions of fish groups by OmegaQuant Europe. Analysis of covariance, adjusting for age, BMI, and baseline O3I, examined the effect of the fish intervention on the O3I. Chi-square test was used to compare the O3I between groups when categorised as at risk (<4%), intermediate risk (48%) and low risk (>8%).

Participants had a mean ± SD age of 25.5 ± 6.4 years. Baseline median (IQR) O3I of the cohort was 5.7 (5.2, 6.7) %. There was no significant difference in the O3I between treatment groups at baseline. Consumption of two portions of fish significantly increased the O3I when compared to the consumption of no fish [6.73 (5.41, 7.38) % vs 5.58 (5.12, 6.49) %, respectively, p = 0.034]. Those consuming two portions of sardines, an oily fish high in n-3 PUFAs, had a significantly greater O3I when compared to those consuming two portions of tuna [7.38 (6.83, 8.37) % vs 5.61 (5.29, 6.79) %, respectively, p<0.001]. Post-intervention, the proportion of participants in the low risk O3I category (>8%) was greater in the two portions of fish group when compared to the control group; albeit this did not reach statistical significance (p = 0.104).

In support of the current dietary guidelines, increasing fish consumption of low consumers to two portions of any fish per week will increase the O3I. Future research should determine the potential cardioprotective properties of a higher O3I as a result of consuming fish.

Dietary intake can influence immune function indirectly by affecting the gut microbiota composition and metabolism(1). Fish consumption has been shown to positively regulate the gut microbiota in humans(2,3);albeit in those studies fish was consumed in high amounts (500-750g/week) and immune function was not investigated. This study investigated the effect of consuming the UK dietary recommendation for fish(4) (2 portions [140-280g/week], one of which is oily) on the gut microbiota alpha diversity. Further, we examined if changes (pre- to post-intervention) in the gut microbiota composition were associated with changes in immune cytokine concentrations.

An 8-week randomised controlled trial in low fish consuming women of childbearing age (n = 41; median age 23y) investigated the effect of consuming 1 or 2 portions of fish (tuna or sardines)/week compared to not consuming fish. A blood sample was collected to measure inflammatory cytokines (tumour necrosis factor-a, interleukin [IL]-1b, IL-5, IL-6, IL-17A and IL-22) pre-and post-intervention. Faecal samples were collected at both timepoints and extracted DNA was used to determine gut microbiota compositional profiles using 16S metagenomic sequencing (Illumina, USA). Statistical analysis investigated significant differences in changes in gut microbiota alpha diversity and compositional relative abundances between fish intervention (N = 26) and control (N = 15), then secondary analysis stratified by portion size (1 vs 2 portions) and type of fish (tuna vs sardines). Differences in cytokines between fish intervention and control were assessed by Mann-Whitney U. Spearman rank coefficient assessed associations between the changes in gut microbiota relative abundances with cytokine changes in fish and control groups.

Fish consumption increased gut microbiota alpha diversity indices (Chao1 [7.37±41.23], Simpson [0.003±0.163], Shannon [0.07±0.33], phylogenetic diversity [0.35±2.59], observed species [9.00±40.06]), albeit this was not significant compared to the control group (p>0.05). Consumption of fish, specifically sardines, for 8 weeks significantly reduced Bacteroidetes (-4.77±4.88%) when compared to control (+4.15±7.58%) (p<0.01). No significant differences were observed between the change in relative abundances of gut microbiota at genus-level taxa or inflammatory cytokines between the fish intervention and control. In the fish intervention group, increases in IL-17A, IL-22 and IL-6 concentrations were positively correlated with changes in Alistipes, Rhodococcus, Haemophilus, Barnesiella and Akkermansia relative abundances (p<0.05).

Although not statistically significant, consistent findings suggest that fish intake, in line with dietary guidelines, may have favourable impact on gut microbiota. Sardines, oily fish rich in n-3 polyunsaturated fatty acids, may have health benefits in disease states where Bacteroidetes is elevated; nevertheless, further research is required in a larger cohort over a longer period.

Converting measurements of ice-sheet surface elevation change to mass change requires measurements of accumulation and knowledge of the evolution of the density profile in the firn. Most firn-densification models are tuned using measured depth–density profiles, a method which is based on an assumption that the density profile in the firn is invariant through time. Here we present continuous measurements of firn-compaction rates in 12 boreholes near the South Pole over a 2 year period. To our knowledge, these are the first continuous measurements of firn compaction on the Antarctic plateau. We use the data to derive a new firn-densification algorithm framed as a constitutive relationship. We also compare our measurements to compaction rates predicted by several existing firn-densification models. Results indicate that an activation energy of 60 kJ mol−1, a value within the range used by current models, best predicts the seasonal cycle in compaction rates on the Antarctic plateau. Our results suggest models can predict firn-compaction rates with at best 7% uncertainty and cumulative firn compaction on a 2 year timescale with at best 8% uncertainty.

Maternal fish consumption exposes the fetus to beneficial nutrients and potentially adverse neurotoxicants. The current study investigated associations between maternal fish consumption and child neurodevelopmental outcomes. Maternal fish consumption was assessed in the Seychelles Child Development Study Nutrition Cohort 1 (n 229) using 4-day food diaries. Neurodevelopment was evaluated at 9 and 30 months, and 5 and 9 years with test batteries assessing twenty-six endpoints and covering multiple neurodevelopmental domains. Analyses used multiple linear regression with adjustment for covariates known to influence child neurodevelopment. This cohort consumed an average of 8 fish meals/week and the total fish intake during pregnancy was 106·8 (sd 61·9) g/d. Among the twenty-six endpoints evaluated in the primary analysis there was one beneficial association. Children whose mothers consumed larger quantities of fish performed marginally better on the Kaufman Brief Intelligence Test (a test of nonverbal intelligence) at age 5 years (β 0·003, 95 % CI (0, 0·005)). A secondary analysis dividing fish consumption into tertiles found no significant associations when comparing the highest and lowest consumption groups. In this cohort, where fish consumption is substantially higher than current global recommendations, maternal fish consumption during pregnancy was not beneficially or adversely associated with children’s neurodevelopmental outcomes.

The Hierarchical Taxonomy of Psychopathology (HiTOP) has emerged out of the quantitative approach to psychiatric nosology. This approach identifies psychopathology constructs based on patterns of co-variation among signs and symptoms. The initial HiTOP model, which was published in 2017, is based on a large literature that spans decades of research. HiTOP is a living model that undergoes revision as new data become available. Here we discuss advantages and practical considerations of using this system in psychiatric practice and research. We especially highlight limitations of HiTOP and ongoing efforts to address them. We describe differences and similarities between HiTOP and existing diagnostic systems. Next, we review the types of evidence that informed development of HiTOP, including populations in which it has been studied and data on its validity. The paper also describes how HiTOP can facilitate research on genetic and environmental causes of psychopathology as well as the search for neurobiologic mechanisms and novel treatments. Furthermore, we consider implications for public health programs and prevention of mental disorders. We also review data on clinical utility and illustrate clinical application of HiTOP. Importantly, the model is based on measures and practices that are already used widely in clinical settings. HiTOP offers a way to organize and formalize these techniques. This model already can contribute to progress in psychiatry and complement traditional nosologies. Moreover, HiTOP seeks to facilitate research on linkages between phenotypes and biological processes, which may enable construction of a system that encompasses both biomarkers and precise clinical description.

Inadequate sleep and poor eating behaviours are associated with higher risk of childhood overweight and obesity. Less is known about the influence sleep has on eating behaviours and consequently body composition. Furthermore, whether associations differ in boys and girls has not been investigated extensively. We investigate associations between sleep, eating behaviours and body composition in cross-sectional analysis of 5-year-old children. Weight, height, BMI, mid upper arm circumference (MUAC), abdominal circumference (AC) and skinfold measurements were obtained. Maternal reported information on child’s eating behaviour and sleep habits were collected using validated questionnaires. Multiple linear regression examined associations between sleep, eating behaviours and body composition. Sleep duration was negatively associated with BMI, with 1-h greater sleep duration associated with 0·24 kg/m2 (B = 0·24, CI −0·42, −0·03, P = 0·026) lower BMI and 0·21 cm lower (B = –0·21, CI −0·41, −0·02, P = 0·035) MUAC. When stratified by sex, girls showed stronger inverse associations between sleep duration (h) and BMI (kg/m2) (B = –0·32; CI −0·60, −0·04, P = 0·024), MUAC (cm) (B = –0·29; CI −0·58, 0·000, P = 0·05) and AC (cm) (B = –1·10; CI −1·85, −0·21, P = 0·014) than boys. Positive associations for ‘Enjoys Food’ and ‘Food Responsiveness’ with BMI, MUAC and AC were observed in girls only. Inverse associations between sleep duration and ‘Emotional Undereating’ and ‘Food Fussiness’ were observed in both sexes, although stronger in boys. Sleep duration did not mediate the relationship between eating behaviours and BMI. Further exploration is required to understand how sleep impacts eating behaviours and consequently body composition and how sex influences this relationship.

Optimal maternal long-chain PUFA (LCPUFA) status is essential for the developing fetus. The fatty acid desaturase (FADS) genes are involved in the endogenous synthesis of LCPUFA. The minor allele of various FADS SNP have been associated with increased maternal concentrations of the precursors linoleic acid (LA) and α-linolenic acid (ALA), and lower concentrations of arachidonic acid (AA) and DHA. There is limited research on the influence of FADS genotype on cord PUFA status. The current study investigated the influence of maternal and child genetic variation in FADS genotype on cord blood PUFA status in a high fish-eating cohort. Cord blood samples (n 1088) collected from the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2) were analysed for total serum PUFA. Of those with cord PUFA data available, maternal (n 1062) and child (n 916), FADS1 (rs174537 and rs174561), FADS2 (rs174575), and FADS1-FADS2 (rs3834458) were determined. Regression analysis determined that maternal minor allele homozygosity was associated with lower cord blood concentrations of DHA and the sum of EPA + DHA. Lower cord blood AA concentrations were observed in children who were minor allele homozygous for rs3834458 (β = 0·075; P = 0·037). Children who were minor allele carriers for rs174537, rs174561, rs174575 and rs3834458 had a lower cord blood AA:LA ratio (P < 0·05 for all). Both maternal and child FADS genotype were associated with cord LCPUFA concentrations, and therefore, the influence of FADS genotype was observed despite the high intake of preformed dietary LCPUFA from fish in this population.

Optimal maternal polyunsaturated fatty acid (PUFA) status is essential for foetal development. The desaturase enzymes, encoded by the fatty acid desaturase (FADS) genes, are involved in the endogenous synthesis of long chain (LC)PUFA and influence maternal LCPUFA concentrations. The minor allele of various FADS SNPs has been associated with increased maternal concentrations of the precursors linoleic acid (LA) and α-linolenic acid (ALA), and lower concentrations of the LCPUFA arachidonic acid (AA) and docosahexaenoic acid (DHA); however, there is limited research to date on the influence of FADS genotype on cord PUFA status. The aim of the current study was to investigate the influence of maternal and child genetic variation on cord blood PUFA status in a high fish-eating cohort.

Cord blood samples collected from mother-child pairs (n = 1088) taking part in the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2) were analysed for total serum PUFA. Maternal (n = 1088) and child genotype (n = 592) were determined for the FADS SNPs rs174537, rs174561, rs174575, and rs3834458. Regression analysis determined associations between maternal and child FADS genotype and cord PUFA status. In all regression models, the major allele homozygote genotype for each SNP was used as the reference group.

Directions of significant associations were as predicted. In mothers, the minor allele homozygote genotype for SNPs rs174537, rs174561 and rs3834458 was associated with lower cord DHA and lower total n-3 PUFA when compared to the major allele homozygous genotype (p < 0.05 for all). The heterozygous genotype was associated with increased concentrations of LA compared to the reference genotype for rs174561 (p = 0.021) and rs383448 (p = 0.023). In children, the heterozygous genotype was associated with lower AA concentrations and lower cord n-6:n-3 ratio for all SNPs (p < 0.05 for all) compared to those with the major allele homozygous genotype. A lower cord AA:LA ratio was also observed for children heterozygous for rs174547, rs174561 and rs174575 (p < 0.05 for all). Contrary to expected, there were no associations between cord PUFA concentrations and child minor allele homozygous genotype.

The current study indicates that variation in maternal and child FADS genotype influences cord PUFA concentrations, despite the high intake of preformed dietary LCPUFA from fish in this population. The sample size for minor allele homozygous children was likely too small to observe any statistically significant associations in the current analysis. Further research is needed to determine whether increased dietary intake can compensate for lower PUFA status as a result of FADS genotype.