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View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Serveur académique lausannois International Journal of Epidemiology, 2018, 1–11 doi: 10.1093/ije/dyy274 Opinion Downloaded from https://academic.oup.com/ije/advance-article-abstract/doi/10.1093/ije/dyy274/5240939 by Universite and EPFL Lausanne user on 21 December 2018 Opinion Precision nutrition: hype or hope for public health interventions to reduce obesity? 1 1 2 AngelineChatelan, *MurielleBochud andKatherineLFrohlich 1 Institute of Social and Preventive Medicine, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland and 2De´partement de me´decine sociale et pre´ventive, Ecole de Sante´ Publique & Institut de recherche en sante´ publique de l’Universite´ de Montre´al, Universite´ de Montre´al, Montreal, QC, Canada *Corresponding author. Institut universitaire de me´decine sociale et pre´ventive (IUMSP), Biopoˆle 2, Route de la Corniche 10, CH-1010 Lausanne, Switzerland. E-mail: angeline.chatelan@chuv.ch Editorial decision 5 November 2018; Accepted 17 November 2018 Abstract High-income countries are experiencing an obesity epidemic that follows a socioeco- nomic gradient, affecting groups of lower socioeconomic status disproportionately. Recent clinical findings have suggested new perspectives for the prevention and treatment of obesity, using personalized dietary approaches. Precision nutrition (PN), also called personalized nutrition, has been developed to deliver more preventive and practical dietary advice than ‘one-size-fits-all’ guidelines. With interventions becoming increasingly plausible at a large scale thanks to artificial intelligence and smartphone applications, some have begun to view PN as a novel way to deliver the right dietary intervention to the right population. We argue that large-scale PN, if taken alone, might be of limited interest from a public health perspective. Building on Geoffrey Rose’s theory regarding the differences in individual and population causes of disease, we show that large-scale PN can only address some individual causes of obesity (causes of cases). This individual-centred approach is likely to have a small impact on the distribution of obesity at a population level because it ignores the population causes of obesity (causes of incidence). The latter are embedded in the populations’ social, cultural, economic and political contexts that make environments obesogenic. Additionally, the most socially privileged groups in the population are the most likely to respond to large-scale PN interventions. This could have the undesirable effect of widening social inequalities in obesity. We caution public health actors that interventions based only on large-scale PN are unlikely, despite current expectations, to improve dietary intake or reduce obesity at apopulationlevel. Key words: Precision nutrition, personalized nutrition, obesity, population interventions, social inequalities in health, obesogenic environments C VTheAuthor(s) 2018. Published by Oxford University Press on behalf of the International Epidemiological Association. 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com 2 International Journal of Epidemiology, 2018, Vol. 0, No. 0 Key Messages • Some public health actors have begun to view large-scale precision nutrition as a novel opportunity to provide the right dietary intervention to the right population at the right time. Downloaded from https://academic.oup.com/ije/advance-article-abstract/doi/10.1093/ije/dyy274/5240939 by Universite and EPFL Lausanne user on 21 December 2018 • Large-scale precision nutrition is an individual-centred approach focusing on behavioural modification in large num- bers, and not a true population approach as defined by Geoffrey Rose. • Large-scale precision nutrition is likely to have a limited impact on obesity at a population level as it neglects popula- tion causes of obesity that are rooted in obesogenic environments. • Early adoption and achievement of improved dietary habits based on precision nutrition are more likely among more socially privileged members of the population, which would exacerbate socioeconomic inequalities in diet and obesity. • If taken alone, interventions based on large-scale precision nutrition are unlikely to improve dietary intake or reduce obesity at a population level. optimal diet is not the same for everyone. In brief, PN aims Introduction Most high-income countries are experiencing an obesity at delivering tailored nutritional recommendations based on 1 combined information from individuals’ gut microbiota, ge- epidemic, since 1975. For example, in the USA, more than 37–42 one in three adults and one in six children were estimated netic, physiological, and behavioural backgrounds. 2 Following these promising results in clinical re- to be obese in 2015. Obesity has been linked to search,27–36 some large public research funders, such as the numerous non-communicable diseases such as diabetes, 43 cardiovascular disease, osteoarthritis and certain forms of EU Horizon 2020 programme, have encouraged 3–5 researchers to test solutions providing tailored nutritional cancer. According to the 2016 Global Burden of 6 advice to large numbers of people, including healthy indi- Disease, an unbalanced diet, obesity, and high fasting plasma glucose were among the top six leading risk factors viduals. An international trial, Food4Me, was recently for disability-adjusted life-years in high-income countries. launched with 1600 volunteers to test the opportunities 44 In these countries, the incidence and prevalence of obesity and challenges of PN in the general population. Within this context, some39,42,45,46 have begun to consider PN as follows a socioeconomic gradient, whereby individuals with lower education, occupation and income are dispro- an emerging tool for public health to reduce obesity and portionally affected.7–9 In Spain, Italy and France for in- obesity-related diseases, notably because precision stance, the least educated women are over four times as approaches have a marked preventive component. likely to be obese as the most educated ones.10 In parallel, advances in ‘omics’ technologies and wear- Diet is a major modifiable determinant of obesity. able devices facilitate less costly collection and analysis of Multiple public health interventions to improve population massive data. This makes scaleable delivery of tailored nu- 38,39,42 dietary intake have been implemented to date. Some tritional advice increasingly plausible. Thanks to individual-centred interventions have aimed at providing in- these technical developments and the clinical context formation about healthy eating. They used, for example, explainedabove,PNcouldbeviewedasanovelopportunity mass campaigns to disseminate dietary guidelines (e.g. ‘5 a to provide the right dietary intervention to the right popula- 11–13 47–49 day’) and food guides (e.g. MyPlate in the USA). More tion at the right time, and on a large scale. In this paper, recent interventions have focused on shaping the food envi- we explore the promises and potential limitations of inter- ronment through structural measures. Classical examples ventions based on large-scale PN. We question their rele- 14,15 vance in balancing individuals’ diet and addressing obesity are compulsory nutritional standards for school meals 16–18 at a population level. We build our argument on Geoffrey or taxes on sugar-sweetened beverages. So far out- 50,51 comes have been disappointing. People largely fail to follow Rose’s theory regarding the differences in individual 19–22 and population causes of disease. We finally argue that the dietary guidelines. As for obesity, the prevalence 2,23 24 large-scale PN could possibly have the unintended effect of has not declined, and social inequalities in diet and 10,25,26 exacerbating social inequalities in obesity. obesity havepersisted or even increased. 27–35 Recent research findings, particularly by Zeevi 36 et al. have suggested new perspectives for the prevention andtreatment of obesity-related diseases, using personalized Whatislarge-scaleprecisionnutrition? dietary approaches. Precision nutrition (PN), also called per- 36 Modelled after PN in clinical settings, large-scale PN sonalized nutrition, is based on the postulate that the relies on the collection and analysis of several types of data International Journal of Epidemiology, 2018, Vol. 0, No. 0 3 from eating behaviour, physical activity, deep phenotyp- cholesterol, carotenes and omega 3 index; (iii) diet and ing, nutrigenomics, microbiomics/metagenomics and phenotype plus genotype (i.e. specific variants on five diet- 37–42 44 metabolomics (Table 1). These data serve to define responsive genes). the appropriate diet for each individual, or more realisti- Once the desired level of precision/information is de- Downloaded from https://academic.oup.com/ije/advance-article-abstract/doi/10.1093/ije/dyy274/5240939 by Universite and EPFL Lausanne user on 21 December 2018 49,52 cally, each population sub-stratum. Different amounts fined, data can be collected on a large scale using personal of data can be collected and analysed depending on the in- smartphones and other relatively inexpensive and reliable frastructure availability and financial resources. For exam- wearable devices, such as an electronic food diary and ple, in the Food4Me trial, the intervention involved the wristband for accelerometry.38,39 In parallel, new tools delivery of personalized nutrition advice based on data (Table 1), such as dried blood spot testing42 already rou- 53 from: (i) current diet; or (ii) diet plus phenotypic traits tinely used for the Guthrie test in newborns, and simple such as waist circumference, serum glucose, total 36,54 stool kits, enable biosample collection from home or a Table1.Potential sources of data for tailored nutritional advice in large-scale precision nutrition interventions Data Aimsofdatacollection Methodstoproducedata Infrastructures and tools to col- lect, analyse and store data Eating behaviour Toevaluate: Dietary assessment on several days • Driedbloodspottesting • Dietary intake (e.g. food using: • Saliva swabs consumption, use of nutrient • Onlinefooddiary • Stool kits supplements) • Smartphoneapplications (self- • Shipmentmaterial • Eating behaviour description and quantification of • Localpharmacynetworks consumedfoods) • Accelerometers • Digital photography (semi-auto- • Smartphoneandotherdigital maticidentification and quantifi- technologies cation of consumed foods) • Biobanks Physical activity Tomeasurephysicalactivity Accelerometry techniques using: • Linkagewithelectronic level • Wearable/portable devices (e.g. health records Toestimateenergyexpenditure wristband) • Biomedical laboratories • Onlinequestionnaire • Artificial intelligence etc. Deep Toassess: Anthropometric measurements phenotyping • Bodycomposition (e.g. weight, waist circumfer- • Nutritional status ence, bone densitometry) • Otherrisk factors for Clinical chemistry from various diet-related diseases bio-samples (e.g. plasma, urine, saliva) to assess visceral fat dis- tribution, insulin resistance, low-density lipoprotein choles- terol, nutrient deficiencies, etc. Nutrigenomics Tolookforgeneticvariants DNAextractionandgenotypingof associated with diet-related selected loci from whole-blood diseases and/or responsive to samples dietary changes Microbiomics/ Tounderstandtheinterplay Faeces collection to sequence the metagenomics betweendietandgut microorganismspresent in the microbiota gut for microbial profiling and detection of dysbiosis Metabolomics Tounderstandhowthebody Complexchemicalanalysesfrom metabolizes/uses nutrients biosamples (e.g. serum, plasma, urine) using: • Nuclearmagneticresonance spectroscopy • Massspectrometry-based techniques 4 International Journal of Epidemiology, 2018, Vol. 0, No. 0 local pharmacy. The Food4Me intervention was entirely challenges are currently being addressed by some countries internet-delivered, for instance. Participants themselves that have launched large-scale precision medicine projects, collected both biosamples, using the saliva swabs for geno- such as the Precision Medicine Initiative in one million US 72 Downloaded from https://academic.oup.com/ije/advance-article-abstract/doi/10.1093/ije/dyy274/5240939 by Universite and EPFL Lausanne user on 21 December 2018 typing and dried blood spots for phenotyping. They fol- residents, and the human biomonitoring project lowed online demonstrations, and sent their biological (HBM4EU) in 28 European countries.73 On the other material by conventional mail.44 The advances of labora- hand, the effectiveness associated with both identifying the tory analytical techniques (e.g. DNA sequencing, mass individual risk and delivering personal messages for pre- 39,42 spectrometry), bioinformatics, and artificial intelli- vention and treatment of obesity-related disease is dis- 4,38,40,74–77 gence (e.g. machine-learning algorithms, deep learn- puted. The 2018 Lancet review by Wang and 36,38,55,56 38 ing) render the analysis and interpretation of Hu concluded that evidence is currently lacking to sup- large datasets less and less expensive and time-consuming. port the additional benefits of PN over ‘one-size-fits-all’ Lastly, smartphone applications allow large-scale dis- nutrition intervention in the prevention and treatment of semination of personalized advice directly to individuals. type 2 diabetes. Evidence regarding effectiveness and cost- For instance, the applications delivered by the companies effectiveness of large-scale PN in the general population is 57 58 DayTwo and Viome can provide a personal score for even scarcer. To date, the Food4Me trial has determined foods or recipes regarding their potential positive or nega- that participants receiving personalized advice had a tive impact on blood glucose level. The enterprise habit59 healthier diet compared with controls receiving standard even offers detailed menu plans to comply with personal- guidelines after the 6-month intervention (completion rate: 78 ized recommended intake in terms of protein, carbohy- 79%). However, no significant changes in weight or drate and fat. waist circumference were observed, even when phenotypic or genotypic data were considered to personalized diet. The question of effectiveness on population health will Large-scale precision nutrition: promises probably remain open for some years. andchallenges Thecentral promise of large-scale PN is personalized inter- ventions based on more: (i) preventive (predictive and ac- Obeseindividualsandobesepopulations curate); (ii) practical (understandable and implementable); In public health, two main traditional strategies have and (iii) dynamic nutritional advice than ‘one-size-fits-all’ existed for preventive interventions: high-risk and popula- 39 50,51 guidelines. First, PN advocates presume that nutritional tion approaches. The traditional population approach advice is likely to be more predictive because the personal seeks an improvement of overall population health by risk of developing specific diseases (e.g. based on polygenic shifting the distribution of exposure risk in a favourable di- risk scores) and biomedical context can be consid- rection in the entire population (Figure 1A). With the as- 40,49,60 ered. Advice could also be more accurate due to sumption that ‘a large number of people at a small risk more precise dietary intake and nutritional status assess- maygive rise to more cases of disease than the small num- 61–65 ment and better anticipation of interpersonal variabil- ber who are at a high risk’, the population approach con- ity in food metabolic response.36,66,67 Second, personalized trasts with the high-risk approach.50 The high-risk nutritional advice may be easily understood, as messages approach proposes targeted interventions addressed only could be delivered in a simpler way using modern commu- to individuals screened for their higher probability of de- nication techniques.68,69 Advice may also be more imple- veloping the disease.50 mentable as adapted to actual food consumption, personal Large-scale PN targets the whole population in the 68–70 food preferences and lifestyle. Third, nutritional ad- spirit of a traditional population approach. Both preven- vice would evolve following the personal dietary and bio- tive strategies can be used for primary and secondary pre- medical evolutions of each individual as automatically vention. However, large-scale PN interventions processed and refined over time through new data.39 In substantially differ from the traditional population inter- sum,large-scale PN promises better individual risk identifi- ventions, in the way of achieving the distribution shift. The cation through comprehensive screening and behavioural former targets individual risk with precision behavioural modification in line with these identified risks. measures in large numbers, whereas the latter targets over- At present, large-scale PN faces two main challenges, all population risk with structural/environmental meas- however. On the one hand, its application on a large scale ures, as shown below. raises organizational, legal and ethical questions, notably In the 1985 seminal article ‘Sick individuals and sick 50 regarding biobank management, data protection and in- populations’, still considered relevant for modern public 42,52,71 79 formed consent. However, these technical health, Geoffrey Rose suggested a distinction be made
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