Developing and testing personalised nutrition feedback for more sustainable healthy diets: the MyPlanetDiet randomised controlled trial protocol.

PURPOSE: Agriculture and food production contribute to climate change. There is mounting pressure to transition to diets with less environmental impact while maintaining nutritional adequacy. MyPlanetDiet aimed to reduce diet-related greenhouse gas emissions (GHGE) in a safe, nutritionally adequate, and acceptable manner. This paper describes the trial protocol, development, and testing of personalised nutrition feedback in the MyPlanetDiet randomised controlled trial (RCT). METHODS: MyPlanetDiet was a 12-week RCT that provided standardised personalised nutrition feedback to participants based on new sustainable healthy eating guidelines (intervention) or existing healthy eating guidelines (control) using decision trees and corresponding feedback messages. To test the personalised nutrition feedback, we modelled a sample of 20 of the MyPlanetDiet participants baseline diets. Diets were modelled to adhere to control and intervention decision trees and feedback messages. Modelled nutrient intakes and environmental metrics were compared using repeated measure one-way analysis of covariance. RESULTS: Intervention diets had significantly lower (p < 0.001) diet-related GHGE per 2500 kilocalories (kcal) (4.7 kg CO2-eq) relative to control (6.6 kg CO2-eq) and baseline (7.1 kg CO2-eq). Modelled control and intervention diets had higher mean daily intakes of macronutrients (carbohydrates, fibre, and protein) and micronutrients (calcium, iron, zinc, and iodine). Modelled control and intervention diets had lower percent energy from fat and saturated fat relative to baseline. CONCLUSIONS: Adherence to the MyPlanetDiet personalised nutrition feedback would be expected to lead to better nutrient intakes and reduced diet-related GHGE. The MyPlanetDiet RCT will test the effectiveness and safety of personalised feedback for a more sustainable diet. TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION: Clinical trials registration number: NCT05253547, 23 February 2022.

What factors influence sustainable and healthy diet consumption? A review and synthesis of literature within the university setting and beyond.

Globally, typical dietary patterns are neither healthy nor sustainable. Recognizing the key role of dietary change in reducing noncommunicable disease risk and addressing environmental degradation, it is crucial to understand how to shift individuals toward a sustainable and healthy diet (SHD). In this literature review, we introduced the concept of a SHD and outlined the dietary behaviors necessary to transition toward SHD consumption; we reviewed the literature on factors that may influence sustainable (and unsustainable) dietary behaviors in adults; and we developed a novel scoring system to rank factors by priority for targeting in future research. Given the significant potential to promote a sustainable and healthy dietary transition on the university campus-where factors that may impact dietary behaviors can be targeted at all levels of influence (i.e., individual, interpersonal, environmental, policy)-we narrowed our focus to this setting throughout. Aided by our novel scoring system, we identified conscious habitual eating, product price, food availability/accessibility, product convenience, self-regulation skills, knowledge of animal ethics/welfare, food promotion, and eating norms as important modifiable factors that may influence university students' dietary behaviors. When scored without consideration for the university population, these factors were also ranked as highest priority, as was modified portion sizes. Our findings offer insight into factors that may warrant attention in future research aimed at promoting SHDs. In particular, the high-priority factors identified from our synthesis of the literature could help guide the development of more personalized dietary behavioral interventions within the university setting and beyond.

Moving towards more sustainable diets: Is there potential for a personalised approach in practice?

Discourse on the relationship between food production, healthy eating and sustainability has become increasingly prominent and controversial in recent years. Research groups often take one perspective when reporting on sustainable diets, and several often neglect considerations for the multiple aspects that make a diet truly sustainable, such as cultural acceptability, differences in nutritional requirements amongst the population and the efficiency of long-term dietary change. Plant-based diets are associated with lower greenhouse gas emissions (GHGEs) and have been linked with better health outcomes, including lower risk of diet-related chronic disease. However, foods associated with higher GHGE, such as lean red meat, fish and dairy, have beneficial nutritional profiles and contribute significantly to micronutrient intakes. Some research has shown that diets associated with lower GHGE can be less nutritionally adequate. Several countries now include sustainability recommendations in dietary guidelines but use vague language such as "increase" or "consume regularly" when referring to plant-based foods. General population-based nutrition advice has poor adherence and does not consider differences in nutritional needs. Although modelling studies show potential to significantly reduce environmental impact with dietary changes, personalising such dietary recommendations has not been studied. Adapting recommendations to the individual through reproducible methods of personalised nutrition has been shown to lead to more favourable and longer-lasting dietary changes compared to population-based nutrition advice. When considering sustainable healthy dietary guidelines, personalised feedback may increase the acceptability, effectiveness and nutritional adequacy of the diet. A personalised approach has the potential for delivering a new structure of more sustainable healthy food-based dietary guidelines. This review evaluates the potential to develop personalised sustainable healthy food-based dietary guidelines and discusses potential implications for policy and practice.

Serum 25-hydroxyvitamin D response to vitamin D supplementation using different lipid delivery systems in middle-aged and older adults: a randomised controlled trial.

Food fortification improves vitamin D intakes but is not yet mandated in many countries. Combining vitamin D with different dietary lipids altered vitamin D absorption in in vitro and postprandial studies. This randomised, placebo-controlled trial examined the effect of the lipid composition of a vitamin D-fortified dairy drink on change in 25-hydroxyvitamin D (25(OH)D) concentrations. Sixty-three healthy adults aged 50+ years were randomised to one of the following for 4 weeks: vitamin D-fortified olive oil dairy drink, vitamin D-fortified coconut oil dairy drink, vitamin D supplement or placebo control dairy drink. All vitamin D groups received 20 µg of vitamin D3 daily. Serum was collected at baseline and post-intervention to measure 25(OH)D concentrations and biomarkers of metabolic health. Repeated-measures general linear model ANCOVA (RM GLM ANCOVA) compared changes over time. There was a significant time × treatment interaction effect on 25(OH)D concentrations for those classified as vitamin D-insufficient (P < 0·001) and -sufficient at baseline (P = 0·004). 25(OH)D concentrations increased significantly for all insufficient participants receiving vitamin D3 in any form. However, for vitamin D-sufficient participants at baseline, 25(OH)D concentrations only increased significantly with the coconut oil dairy drink and supplement. There was no effect of vitamin D on biomarkers of metabolic health. Vitamin D fortification of lipid-containing foods may be used in lieu of supplementation when supplement adherence is low or for individuals with dysphagia. These results are important given the recent recommendation to increase vitamin D intakes to 15-20 µg for older adults in Ireland.

Influence of Vitamin D Status and Supplementation on Metabolomic Profiles of Older Adults.

Metabolomics can identify metabolite patterns associated with different nutrition phenotypes and determine changes in metabolism in response to nutrition interventions. Vitamin D insufficiency is associated with increased metabolic disease risk; however, the role of vitamin D in metabolic health is not fully understood. This randomised, placebo-controlled trial (RCT) examined the influence of vitamin D status and the effect of vitamin D supplementation on metabolomic profiles in older adults. Healthy adults aged 50+ were randomly assigned to consume 20 µg vitamin D3 or a placebo daily for 4 weeks. Serum samples were collected at baseline and post-intervention for 25(OH)D and metabolomics analysis via liquid chromatography tandem mass spectrometry (LC-MS/MS). Pearson's correlation examined relationships between 25(OH)D and metabolite concentrations. GLM ANCOVA compared metabolite concentrations between vitamin D-insufficient (<50 nmol/L) and -sufficient (>50 nmol/L) participants. The repeated-measures general linear model of covariance (RM GLM ANCOVA) examined changes in metabolites over time. Out of 132 metabolites, 2 short chain fatty acid concentrations were higher in the insufficient participants compared to sufficient participants, and 11 glycerophospholipid concentrations were lower in insufficient participants compared to sufficient participants at baseline. Three acylcarnitine concentrations decreased with vitamin D supplementation in vitamin D-insufficient participants. Our findings suggest that vitamin D status influences lipid metabolism in healthy older adults and supports the use of metabolomics in vitamin D research.

Postprandial 25-hydroxyvitamin D response varies according to the lipid composition of a vitamin D3 fortified dairy drink.

In-vitro evidence suggests that the lipid component of foods alters vitamin D absorption. This single-blinded, cross-over postprandial study examined the effect of changing the lipid component of a 20 µg vitamin D3 fortified dairy drink on postprandial 25(OH)D concentrations. Participants consumed one dairy drink per visit: a non-lipid, a pre-formed oleic acid micelle, an olive oil and a fish oil dairy drink. There was a significant time*drink*baseline status effect on 25(OH)D concentrations (p = 0.039). There were no time*drink, time or drink effects on 25(OH)D in vitamin D sufficient participants (>50nmol/L). However, there was an effect of time on changes in 25(OH)D concentrations after the olive oil dairy drink (p = 0.034) in vitamin D insufficient participants (<50nmol/L). There were no effects after the other diary drinks. Olive oil may improve vitamin D absorption from fortified foods. Further research is needed to examine the practical implications of changing the lipid component of fortified foods.

Genetic and Environmental Contributions to Variation in the Stable Urinary NMR Metabolome over Time: A Classic Twin Study.

Genes, sex, age, diet, lifestyle, gut microbiome, and multiple other factors affect human metabolomic profiles. Understanding metabolomic variation is critical in human nutrition research as metabolites that are sensitive to change versus those that are more stable might be more informative for a particular study design. This study aims to identify stable metabolomic regions and determine the genetic and environmental contributions to stability. Using a classic twin design, 1H nuclear magnetic resonance (NMR) urinary metabolomic profiles were measured in 128 twins at baseline, 1 month, and 2 months. Multivariate mixed models identified stable urinary metabolites with intraclass correlation coefficients ≥0.51. Longitudinal twin modeling measured the contribution of genetic and environmental influences to variation in the stable urinary NMR metabolome, comprising stable metabolites. The conservation of an individual's stable urinary NMR metabolome over time was assessed by calculating conservation indices. In this study, 20% of the urinary NMR metabolome is stable over 2 months (intraclass correlation (ICC) 0.51-0.65). Common genetic and shared environmental factors contributed to variance in the stable urinary NMR metabolome over time. Using the stable metabolome, 91% of individuals had good metabolomic conservation indices ≥0.70. To conclude, this research identifies 20% of the urinary NMR metabolome as stable, improves our knowledge of the sources of metabolomic variation over time, and demonstrates the conservation of an individual's urinary NMR metabolome.

Genetic and environmental influences on covariation in reproducible diet-metabolite associations.

BACKGROUND: Early applications of metabolomics in nutrition and health research identified associations between dietary patterns and metabolomic profiles. Twin studies show that diet-related phenotypes and diet-associated metabolites are influenced by genes. However, studies have not examined whether diet-metabolite associations are explained by genetic or environmental factors and whether these associations are reproducible over multiple time points. OBJECTIVE: This research aims to examine the genetic and environmental factors influencing covariation in diet-metabolite associations that are reproducible over time in healthy twins. METHODS: The UCD Twin Study is a semi-longitudinal classic twin study that collected repeated dietary, anthropometric, and urinary data over 2 months. Correlation analysis identified associations between diet quality measured using the Healthy Eating Index (HEI) and urinary metabolomic profiles at 3 time points. Diet-associated metabolites were examined using linear regression to identify those significantly influenced by familial factors between twins and those significantly influenced by unique factors. Cholesky decomposition modeling quantified the genetic and environmental path coefficients through associated dietary components onto the metabolites. RESULTS: The HEI was associated with 14 urinary metabolites across 3 metabolomic profiles (r: ±0.15-0.49). For 8 diet-metabolite associations, genetic or shared environmental factors influencing HEI component scores significantly influenced variation in metabolites (ß: 0.40-0.52). A significant relation was observed between dietary intakes of whole grain and acetoacetate (ß: -0.50, P < 0.001) and ß-hydroxybutyrate (ß: -0.46, P < 0.001), as well as intakes of saturated fat and acetoacetate (ß: 0.47, P < 0.001) and ß-hydroxybutyrate (ß: 0.52, P < 0.001). For these diet-metabolite associations a common shared environmental factor explained 66-69% of variance in the metabolites. CONCLUSIONS: This study shows that diet-metabolite associations are reproducible in 3 urinary metabolomic profiles. Components of the HEI covary with metabolites, and covariation is largely due to the shared environment.

Exploring Covariation between Traditional Markers of Metabolic Health and the Plasma Metabolomic Profile: A Classic Twin Design.

Novel metabolomic profiling techniques combined with traditional biomarkers provide knowledge of mechanisms underlying metabolic health. Twin studies describe the impact of genes and environment on variation in traits. This study aims to identify relationships between traditional markers of metabolic health and the plasma metabolomic profile using a twin modeling approach and determine whether covariation is caused by shared genetic and environmental factors. Using a classic twin design, this study examined covariation between anthropometric, clinical chemistry, and metabolomic profiles. Cholesky decomposition modeling was used to determine the genetic and environmental path coefficients through successive anthropometric and clinical chemistry traits onto metabolomic derived metabolites. This study shows that WC, TAG, and a metabolomic signature composed of 7 metabolites are inter-related, and that covariation can be attributed to common genetic, shared and unique environmental factors as well as unique environmental factors specific to the metabolite. This quantitative modeling connecting the traditional anthropometry and clinical chemistry traits with the more recent and potentially more sensitive metabolomic profile approach may provide further insight on the pleiotropic genes or modifiable environmental factors influencing variation in metabolic health.