Dietary factors, obesity and serum lipoprotein profile : A nutritional epidemiological study in young adult twins

Background: Energy-dense food and low physical activity have been blamed for the dramatic rise in the prevalence of obesity and related metabolic disorders. However, few dietary and physical activity factors have been consistently associated with obesity in observational studies. Self-reported behaviors are prone to misreporting, which may partly explain the inconsistency of previous results. Nutritional biomarkers provide an objective approach to measure habitual intake, but valid biomarkers are not available for all types of dietary exposures. Aims: The aims of this dissertation were to 1) validate self-reported dietary intake and physical activity by using objective co-twin comparison assessments (I) and the doubly labeled water (DLW) technique (II); 2) determine whether eating and physical activity behaviors are associated with body mass index (BMI) and waist circumference (WC) (I, II); 3) examine whether acquired obesity (IV) and dietary factors (III, V) are associated with serum lipoprotein profiles. Materials and methods: The following participants were recruited from the FinnTwin12 and FinnTwin16 studies, two population-based studies on young adult Finnish twins: 1) 713 monozygotic (MZ) and 698 dizygotic (DZ) twin pairs of the same sex who filled in food-frequency questionnaires (FFQ) and co-twin comparison questions (I); 2) 14 MZ twin pairs discordant (BMI difference more than 3kg/m2) and 10 pairs concordant for obesity who provided 3-day food and activity diaries, eating behavior questionnaires, co-twin comparison questions and total energy expenditure (TEE) measurements determined by DLW (II); 3) 15 obesity-discordant and 9 concordant MZ twin pairs who completed 3-day food diaries, physical activity questionnaires and measurements of subcutaneous adipose tissue, visceral adipose tissue and liver fat by magnetic resonance imaging and spectroscopy and of serum lipid determinations by ultracentrifugation, gradient gel electrophoresis and enzymatic techniques (III, IV); 4) 663 twin individuals who provided FFQs and nuclear magnetic resonance spectroscopy-derived measurements of serum lipoproteins and serum docosahexaenoic acid (DHA) as an objective biomarker of DHA intake (V). Results: In both zygosity groups, the co-twins for whom both twin pair members concordantly answered that the identified twin eats more (overall), or eats more fatty foods, or eats more sweet and fatty delicacies, or eats faster, or selects food less according to healthiness or makes less active choices in daily life had significantly higher BMIs and WCs than their twin siblings. Eating more (overall), eating more sweet and fatty delicacies and exercising less remained significant predictors of intrapair differences in BMI and WC independent of each other as evaluated by multivariate regression analysis. Co-twin comparison questions on snacking, fatty foods, sweet and fatty delicacies and healthy foods corresponded well with self-reported food intake in the FFQs. Twin pairs who differed in the overall amount of food they consumed had the largest intrapair differences in BMI (MZ: 1.9 ± 0.1, DZ: 2.9 ± 0.2 kg/m2) and WC (MZ: 5.5 ± 0.6, DZ: 7.5 ± 0.7 cm). However, there were no differences in self-reported intake between these pairs (I). Analysis of obesity-discordant MZ twin pairs confirmed these results, as most pairs agreed that the heavier twins ate more (overall), snacked more and exercised less than the leaner co-twins. Eating behaviors such as eating too much, striving to be thin and body dissatisfaction were more frequently reported by obese co-twins than their lean counterparts. Total energy intake did not differ between the obese and lean co-twins and few differences were found in the 3-day food diary data. Underreporting of actual energy intake was significant for the obese (24.7% of TEE) but not for the lean co-twins (8.4% of TEE) (II). Obesity-discordant pairs differed significantly in their serum lipoprotein profiles, and the acquired accumulation of liver fat was particularly associated with increased concentrations of atherogenic lipids, including low-density lipoprotein (LDL-C) and Apolipoprotein B (ApoB), while physical activity was related to reduced concentrations of atherogenic lipids (IV). Omega-3 polyunsaturated fatty acid intake, as evaluated by self-reporting and serum measurements of DHA, was significantly related to a shift in the serum high-density lipoprotein (HDL) subclass distribution toward larger HDL particle size (III, V). In addition, serum DHA was positively associated with serum LDL particle diameter and negatively associated with triglyceride (TG) concentrations, medium and large very-low density lipoprotein (VLDL) particle concentrations and VLDL particle diameter. A high-fat, high-sucrose, low fiber dietary pattern (labeled junk food ) was positively associated with TG concentrations, a shift in the subclass distribution of VLDL toward larger particles and LDL toward smaller particles, and an increased concentration of small HDL particles in the serum (V). The associations were independent of adiposity and other lifestyle factors, and most were independent of the potential confounding effects of genotype and early environmental factors shared by twins. Conclusions: By using mutual responses of twin pairs, this study provides compelling evidence that acquired eating and physical patterns are important determinants of obesity, but they may be overlooked in population studies that use self-reported data due considerable misreporting of actual energy intakes and exercise behavior by obese subjects. Habitual physical activity and fish intake were related to a favorable serum lipoprotein profile, whereas a high-fat, high-sucrose, low-fiber dietary pattern and accumulation of liver fat associated with an unfavorable serum lipoprotein profile. These results emphasize a healthy lifestyle, in particular reduced portion sizes of energy-dense, nutrient poor foods and regular physical activity as the cornerstone of preventing obesity and lipid disturbances in young adults.Tausta: Energiatiheää ravintoa ja vähäistä liikuntaa on pidetty lihavuuden ja siihen liittyvien aineenvaihduntahäiriöiden huomattavan lisääntymisen syinä. Havainnointitutkimuksissa lihavuuteen on kuitenkin johdonmukaisesti liitetty vain joitakin ruokavalioon ja liikuntaan liittyviä tekijöitä. Kun henkilö ilmoittaa itse käyttäytymisestään, raportit sisältävät herkästi virheitä, mikä saattaa ainakin osittain selittää aiempien tulosten epäjohdonmukaisuutta. Ravitsemukselliset biomerkkiaineet edustavat objektiivista lähestymistapaa tavanomaisen ravinnonsaannin mittaamiseen, mutta valideja biomerkkiaineita ei ole käytettävissä kaikille ravintoaltistuksille. Tavoitteet: Tämän väitöskirjan tavoitteina oli 1) validoida itseraportoitua ruoankäyttöä ja liikuntaa objektiivisten kaksossisarukselle tehtyjen objektiivisten vertailukysymysten (I) ja kaksoismerkityn veden avulla (II); 2) määrittää, ovatko syömis- ja liikuntakäyttäytyminen yhteydessä painoindeksiin (BMI) ja vyötärön ympärysmittaan (1, II); ja 3) tutkia, liittyvätkö hankittu lihavuus (IV) ja ruokavaliotekijät (III, V) seerumin lipoproteiiniprofiiliin. Materiaalit ja menetelmät: Tutkimukseen otettiin mukaan seuraavat osallistujat FinnTwin12- ja FinnTwin16-tutkimuksista (kaksi aikuisten nuorten suomalaisten kaksosten populaatiopohjaista tutkimusta): 1) 713 monotsygoottista (eli geneettisesti identtisiä) ja 698 samaa sukupuolta olevaa ditsygoottista kaksosparia (eli ns. epäidenttisiä kaksosia), jotka vastasivat ruokailutiheyteen liittyviin kyselyihin (FFQ) ja kaksossisarukseen liittyviin vertailukysymyksiin (I); 2) 14 monotsygoottista kaksosparia, jotka erosivat lihavuuden suhteen (BMI-ero yli 3kg/m2), ja 10 samanpainoista paria; parit pitivät kolmen päivän ruoka- ja liikuntapäiväkirjoja, vastasivat syömistapakyselyihin ja kaksossisaruksen vertailukysymyksiin sekä osallistuivat kokonaisenergiankulutuksen mittauksiin, jotka tehtiin kaksoisleimatulla vedellä (II); 3) 15 lihavuuden suhteen eroavaa ja 9 samanpainoista monotsygoottista kaksosparia, jotka pitivät kolmen päivän ruokapäiväkirjaa, vastasivat liikuntakyselyihin ja osallistuivat ihonalaisen rasvakudoksen, vatsaontelon sisäisen rasvakudoksen ja maksan rasvan (magneettikuvaus ja magneettispektroskopialla sekä seerumin lipidien mittaukseen (ultrasentrifugointi, gradienttigeelielektroforeesi ja entsymaattiset tekniikat) (III, IV); 4) 663 aikuista kaksosta, jotka vastasivat ruokafrekvenssikyselyihin ja osallistuivat ydinmagneettisella resonanssilla ja spektroskopialla tehtäviin seerumin lipoproteiinien ja seerumin dokosaheksaeenihapon (DHA) mittauksiin, joista jälkimmäinen toimi DHA:n saannin objektiivisena biomerkkiaineena. Tulokset: Sekä mono- että ditsygoottiryhmissä niillä kaksossisaruksilla, joiden kohdalla kaksosparin molemmat kaksossisarukset vastasivat yhdenmukaisesti, että kyseinen kaksonen joko syö enemmän (yhteensä), syö rasvaisempia ruokia, syö rasvaisia herkkuja, syö nopeammin, ajattelee ruokaa valitessaan ruuan terveellisyyttä vähemmän kuin toinen kaksonen tai tekee arkielämässä vähemmän liikunnallisesti aktiivisia valintoja, oli merkitsevästi suuremmat painoindeksit ja vyötärönympärykset kuin heidän kaksossisaruksillaan. Enemmän syöminen (yhteensä), rasvaiset herkut ja vähäisempi liikunta säilyivät parinvälisten erojen merkitsevinä ennustajina monitekijäisessä regressioanalyysissä toisistaan riippumatta. Kaksossisarusten vertailukyselyt napostelusta, rasvaisista ruuista, rasvaisista herkuista ja terveellisistä ruuista vastasivat hyvin ruokafrekvenssikyselyissä itseraportoitua ravinnonsaantia. Niillä kaksospareilla, joilla ruuan nautittu kokonaismäärä oli erilainen, oli suurin parinsisäinen ero painoindeksissä (monotsygootit: 1,9 ± 0,1, ditsygootit: 2,9 ± 0,2 kg/m2) ja vyötärönympäryksessä (monotsygootit: 5,5 ± 0,6, ditsygootit: 7,5 ± 0,7 cm). Näiden parien välillä ei kuitenkaan ollut eroja itseraportoidussa ravinnonsaannissa (I). Monotsygoottisten, lihavuuden suhteen eroavien kaksosten analysointi varmisti nämä tulokset, sillä useimmat kaksossisarukset kertoivat, että painavampi kaksonen syö enemmän (yhteensä), napostelee useammin ja liikkuu vähemmän kuin laihempi kaksosista. Lihavat kaksossisarukset raportoivat laihoja useammin liiallista syömistä, halua laihtua ja tyytymättömyyttä omaa kehoa kohtaan. Energiansaannin kokonaismäärä ei poikennut näiden lihavien ja laihojen kaksossisarusten välillä, ja kolmen päivän ruoka- ja liikuntapäiväkirjojen välillä havaittiin vain vähän eroja. Energiansaannin aliraportointi on merkitsevää lihavilla (24,7 % kokonaisenergian-saannista), mutta ei laihoilla (8,4 % kokonaisenergiansaannista) kaksossisaruksilla (II). Lihavuuden suhteen eroavilla pareilla oli merkitsevästi erilaiset lipoproteiiniprofiilit, ja erityisesti maksaan kertynyt rasva liittyi aterogeenisten lipidien (LDL-C, ApoB) lisääntyneisiin pitoisuuksiin ja liikunta niiden pienentyneisiin pitoisuuksiin (IV). Itseraportoitujen tietojen ja DHA-seerumimittausten arvioinnin perusteella monityydyttymättömän omega-3-rasvahapon saanti liittyi merkitsevästi HDL-alaluokan jakautumiseen suuremman HDL-partikkelikoon suuntaan (III, V). Seerumin DHA-pitoisuus liittyi lisäksi positiivisesti LDL-partikkelin läpimittaan ja negatiivisesti triglyseridipitoisuuteen ja keskikokoisten ja isojen VLDL- ja VLDL-partikkelien läpimittaan. Runsasrasvainen, runsaasti sakkaroosia sisältävä, vähäkuituinen ruokavalio ("roskaruoka") liittyi korkeampiin triglyseridipitoisuuksiin, VLDL:n alaluokkajakautuman siirtymiseen suurempien partikkelien suuntaan ja LDL:n siirtymiseen pienempien partikkeleiden suuntaan sekä pienten HDL-partikkelien suurentuneeseen pitoisuuteen (V). Nämä yhteydet olivat lihavuudesta ja muista elämäntapatekijöistä riippumattomia, ja useimmat olivat myös kaksosten yhteisen genotyypin ja varhaisten ympäristötekijöiden mahdollisista sekoittavista vaikutuksista riippumattomia. Päätelmät: Tämä tutkimus antaa kiistatonta näyttöä siitä, että omaksutut syömis- ja liikuntatottumukset ovat tärkeitä lihavuutta selittäviä tekijöitä, mutta näitä eroja ei ehkä huomata populaatiotutkimuksissa itseraportoituja tietoja käytettäessä, mikä johtuu lihavien tutkittavien virheellisestä itseraportoinnista. Liikunta ja kalan nauttiminen liittyivät edulliseen seerumin lipoproteiiniprofiiliin, ja runsasrasvainen, runsaasti sakkaroosia sisältävä, vähäkuituinen ruokavalio ja rasvan kertyminen maksaan liittyivät epäsuotuisaan profiiliin. Nämä tulokset korostavat terveellisen ruokavalion, erityisesti vähäisen energiatiheiden, niukasti suojaravintoaineita sisältävien ruokien käytön ja säännöllisen liikunnan merkitystä lihavuuden ja lipidihäiriöiden ehkäisemisessä nuorilla aikuisilla

Nutrient intake and it´s association with bone mineral density in postmenopausal Finnish women

Einleitung: Die Ernährung spielt bei der Prävention von Osteoporose eine große Rolle. Während die Bedeutung einer ausreichenden Versorgung mit Calcium und Vitamin D generell akzeptiert ist, stehen viele andere Ernährungsfaktoren, wie die Aufnahme von Obst und Gemüse in der Literatur zur Diskussion. Ziel der Arbeit: Ziel der vorliegenden Arbeit war es, die Nährstoffaufnahme postmenopausaler finnischer Frauen mittels eines semiquantitativen Häufigkeitsfragebogens (Food Frequency Questionnaire; FFQ) zu ermitteln. Ein weiteres Ziel dieser Arbeit war es den Zusammenhang zwischen der Nährstoffaufnahme, sowie zwischen dem Obst- und Gemüseverzehr und der Knochendichte am Schenkelhals und an der Lendenwirbelsäule zu untersuchen. Material und Methoden: Die Studienteilnehmer waren 101 postmenopausale Frauen im Alter zwischen 68 und 74 Jahren. Die Knochendichte wurde mittels Energien- Röntgen- Absorptiometrie (Dual Energy X-ray Absorptiometry; DXA) am Schenkelhals und an der Lendenwirbelsäule gemessen. Die Nährstoffzufuhr wurde mit einem aus 89 Die Nährstoffzufuhr wurde mittels eines 89 Fragen beinhaltenden, semiquantitatien FFQs ermittelt. Die finnische online Nährwertdatenbank Fineli (www.fineli.fi) wurde verwendet um aufgenommen Lebensmittel in Nährwerte umzurechnen. Die Nährstoffberechung und alle statistischen Auswertungen wurden mit dem Statistikprogramm SPSS für Windows durchgeführt. Alle Studienteilnehmer wurden für jeden Nährstoff in 2 gleich große Gruppen (über und unter dem Median) eingeteilt. Die Gruppenunterteilung wurde durchgeführt, um eventuelle Unterschiede in der mittleren Knochendichte zwischen der Gruppe mit hoher Nährstoffaufnahme (bzw. hohem Obst- und Gemüsekonsum) und niedriger Nährstoffaufnahme (bzw. niedrigem Obst- und Gemüsekonsum) festzustellen. Unterschiede zwischen den Gruppen wurden unter Berücksichtung der konfundierenden Variablen mittels ANOVA (univariate Varianzanalyse) getestet. Ergebnisse: Die DEXA Messwerte der Knochendichte am Schenkelhals ergaben 0.83 ± 0.12 g/cm2 und an der Lendenwirbelsäule 1.08 ± 0.18 g/cm2. Die Erfassung der Energiezufuhr mittels FFQ ergab eine mittlere tägliche Energieaufnahme von 2173 ± 554 kcal. Die Aufnahme von Protein lag bei 17%, die von Fett bei 31% und die von Kohlenhydraten bei 51% der gesamten täglichen Energieaufnahme. Die Aufnahme von Obst und Gemüse betrug im Durchschnitt 649 ± 435 gram täglich. Frauen mit der höchsten Aufnahme von Magnesium wiesen eine signifikant höhere Knochendichte am Oberschenkelhals auf, jedoch war das Ergebnis nach statistischer Kontrolle konfundierender Variablen nicht mehr signifikant. Eine niedrige Vitamin D Aufnahme mit der Nahrung stand mit einer geringeren Knochendichte am Oberschenkelhals in Zusammenhang und das Ergebnis blieb auch nach Berücksichtigung aller konfundierenden Variablen signifikant (p<0.05)

The temporal relationship between parental concern of overeating and childhood obesity considering genetic susceptibility : longitudinal results from the IDEFICS/I.Family study

Background: Many genes and molecular pathways are associated with obesity, but the mechanisms from genes to obesity are less well known. Eating behaviors represent a plausible pathway, but because the relationships of eating behaviors and obesity may be bi-directional, it remains challenging to resolve the underlying pathways. A longitudinal approach is needed to assess the contribution of genetic risk during the development of obesity in childhood. In this study we aim to examine the relationships between the polygenic risk score for body mass index (PRS-BMI), parental concern of overeating and obesity indices during childhood. Methods: The IDEFICS/I.Family study is a school-based multicenter pan-European cohort of children observed for 6 years (mean +/- SD follow-up 5.8 +/- 0.4). Children examined in 2007/2008 (wave 1) (mean +/- SD age: 4.4 +/- 1.1, range: 2-9 years), in 2009/2010 (wave 2) and in 2013/2014 (wave 3) were included. A total of 5112 children (49% girls) participated at waves 1, 2 and 3. For 2656 children with genome-wide data we constructed a PRS based on 2.1 million single nucleotide polymorphisms. Z-score BMI and z-score waist circumference (WC) were assessed and eating behaviors and relevant confounders were reported by parents via questionnaires. Parental concern of overeating was derived from principal component analyses from an eating behavior questionnaire. Results: In cross-lagged models, the prospective associations between z-score obesity indices and parental concern of overeating were bi-directional. In mediation models, the association between the PRS-BMI and parental concern of overeating at wave 3 was mediated by baseline z-BMI (beta = 0.16, 95% CI: 0.10, 0.21) and baseline z-WC (beta = 0.17, 95% CI: 0.11, 0.23). To a lesser extent, baseline parental concern of overeating also mediated the association between the PRS-BMI and z-BMI at wave 3 (beta = 0.10, 95% CI: 0.07, 0.13) and z-WC at wave 3 (beta = 0.09, 95% CI: 0.07, 0.12). Conclusions: The findings suggest that the prospective associations between obesity indices and parental concern of overeating are likely bi-directional, but obesity indices have a stronger association with future parental concern of overeating than vice versa. The findings suggest parental concern of overeating as a possible mediator in the genetic susceptibility to obesity and further highlight that other pathways are also involved. A better understanding of the genetic pathways that lead to childhood obesity can help to prevent weight gain.Peer reviewe

Dietary Intake at 9 Years and Subsequent Body Mass Index in Adolescent Boys and Girls : A Study of Monozygotic Twin Pairs

There is a lack of evidence pointing to specific dietary elements related to weight gain and obesity prevention in childhood and adulthood. Dietary intake and obesity are both inherited and culturally transmitted, but most prospective studies on the association between diet and weight status do not take genetics into consideration. The objective of this study was to document the association between dietary intake at 9 years and subsequent Body Mass Index (BMI) in adolescent monozygotic boy and girl twin pairs. This research used data from 152 twin pairs. Dietary data were collected from two 24-hour-recall interviews with a parent and the child aged 9 years. Height and weight were obtained when the twins were aged 9, 12, 13, and 14 years. Intrapair variability analysis was performed to identify dietary elements related to BMI changes in subsequent years. BMI-discordant monozygotic twin pairs were also identified to analyze the dietary constituents that may have generated the discordance. After eliminating potential confounding genetic factors, pre-adolescent boys who ate fewer grain products and fruit and consumed more high-fat meat and milk had higher BMIs during adolescence; pre-adolescent girls who consumed more grain products and high-fat meat and milk had higher BMIs during adolescence. Energy intake (EI) at 9 years was not related to BMI in subsequent years. Our study suggests that messages and interventions directed at obesity prevention could take advantage of sex-specific designs and, eventually, genetic information.Peer reviewe

A comparison of anthropometric, metabolic, and reproductive characteristics of young adult women from opposite-sex and same-sex twin pairs

Background: Prenatal exposure to androgens has been linked to masculinization of several traits. We aimed to determine whether putative female intra-uterine exposure to androgens influences anthropometric, metabolic, and reproductive parameters using a twin design. Methods: Two cohorts of Finnish twins born in 1975-1979 and 1983-1987 formed the basis for the longitudinal FinnTwin16 (FT16) and FinnTwin12 (FT12) studies. Self-reported anthropometric characteristics, disease status, and reproductive history were compared between 679 same-sex (SS) and 789 opposite-sex (OS) female twins (mean age ± SD: 34 ± 1.1) from the wave 5 of data collection in FT16. Serum lipid and lipoprotein subclass concentrations measured by nuclear magnetic resonance spectroscopy were compared in 226 SS and 169 OS female twins (mean age ± SD: 24 ± 2.1) from the wave 4 of data collection in FT12 and FT16. Results: Anthropometric measures, the prevalence of hypertension and diabetes mellitus type 2 did not differ significantly between females from SS and OS twin pairs at age 34. Similarly, the prevalence of infertility, age at first pregnancy and number of induced and spontaneous abortions did not differ significantly between these two groups of women. The serum lipid and lipoprotein profile did not differ between females from SS and OS twins at age 24. Conclusion: We found no evidence that androgen overexposure of the female fetus affects obesity, metabolic profile, or reproductive health in young adult females. However, these results do not exclude the possibility that prenatal androgen exposure in females could be adversely associated with these phenotypes later in life.Peer reviewe

Weight Status and BMI-related traits in adolescent friendship groups and role of sociodemographic factors : the European IDEFICS/I.Family Cohort

Background: During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors. Methods: Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation. Results: Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed. Conclusion: Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987)

FinnTwin16 : A Longitudinal Study from Age 16 of a Population-Based Finnish Twin Cohort

The purpose of this review is to provide a detailed and updated description of the FinnTwin16 (FT16) study and its future directions. The Finnish Twin Cohort comprises three different cohorts: the Older Twin Cohort established in the 1970s and the FinnTwin12 and FT16 initiated in the 1990s. FT16 was initiated in 1991 to identify the genetic and environmental precursors of alcoholism, but later the scope of the project expanded to studying the determinants of various health-related behaviors and diseases in different stages of life. The main areas addressed are alcohol use and its consequences, smoking, physical activity, overall physical health, eating behaviors and eating disorders, weight development, obesity, life satisfaction and personality. To date, five waves of data collection have been completed and the sixth is now planned. Data from the FT16 cohort have contributed to several hundred studies and many substudies, with more detailed phenotyping and collection of omics data completed or underway. FT16 has also contributed to many national and international collaborations.Peer reviewe

A within-sibling pair analysis of lifestyle behaviours and BMI z-score in the multi-centre I.Family study

Background and aims: By investigating differences in lifestyle behaviours and BMI in sibling pairs, family-level confounding is minimized and causal inference is improved, compared to cross-sectional studies of unrelated children. Thus, we aimed to investigate within-sibling pair differences in different lifestyle behaviours and differences in BMI z-scores in children and adolesents. Methods and results: We examined three groups of sibling pairs 1) all same-sex sibling pairs with maximum 4 years age difference (n = 1209 pairs from 1072 families in 8 countries, mean age 10.7 years, standard deviation 2.4 years), 2) sibling pairs discordant for overweight (n = 262) and 3) twin pairs (n = 85). Usual dietary intake was estimated by 24-h recalls and time spent in light (LPA) and moderate-to-vigorous physical activity (MVPA) was measured by accelerometers. Screen time, sleep and dieting for weight loss were assessed by questionnaires. Within all 3 groups of sibling pairs, more time in MVPA was associated with lower BMI z-score. Higher energy intake was associated with higher BMI z-score within twin pairs and within all sibling pairs who were not currently dieting for weight loss. Regarding LPA, screen time or sleep duration, no or inconsistent associations were observed for the three groups of sibling pairs. Conclusions: MVPA and energy intake were associated with BMI differences within sibling and twin pairs growing up in the same home, thus independent of family-level confounding factors. Future studies should explore whether genetic variants regulating appetite or energy expenditure behaviours account for weight differences in sibling pairs. (C) 2019 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.Peer reviewe

Birth size and gestational age in opposite-sex twins as compared to same-sex twins : An individual-based pooled analysis of 21 cohorts

It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), including 67,850 dizygotic twin individuals. Linear regression analyses showed that boys having a co-twin sister were, on average, 31 g (95%Cl 18 to 45) heavier and 0.16 cm (95%CI 0.045 to 0.274) longer than those with a co-twin brother. In girls, birth size was not associated (5 g birth weight; 95%Cl -8 to -18 and -0.089 cm birth length; 95% CI -0.202 to 0.025) with the sex of the co-twin. Gestational age was slightly shorter in boy-boy pairs than in boy-girl and girl-girl pairs. When birth size was standardized by gestational age, the magnitude of the associations was attenuated in boys, particularly for birth weight. In conclusion, boys with a co-twin sister are heavier and longer at birth than those with a co-twin brother. However, these differences are modest and partly explained by a longer gestation in the presence of a co-twin sister.Peer reviewe

Dietary Behavior and Physical Activity in Children and Adolescents

In recent years, diet- and lifestyle-related disorders have become a major health threat in Europe and worldwide. The contributions in this monograph include 2 review articles and 19 original contributions from several countries that provide new information on the existing research elucidating important aspects of children’s and adolescents’ nutrition and lifestyle behavior. The data included in this Special Issue are from large epidemiological studies, including several multicenter and multinational studies, as well as datasets from surveillance initiatives. The topics of interest of this Special Issue include the co-occurrence of multiple health behaviors in children, the role of parenting and early feeding practices, dairy consumption in childhood, validity of dietary intake data, dietary supplement use in children, as well as socioeconomic disparities and eating culture. The diverse articles in this Special Issue highlight the complexity and extent to which nutrition and physical activity behaviors may influence different health aspects of children and adolescents. As seen by the various findings and recommendations, not only is more work in this area required but the translation of this work to practice and policy is imperative if we are to address the challenges impacting the nutrition, physical activity, and health of young populations