MESTRADO SAÚDE PÚBLICA
Influence of parental child-feeding practices on dietary patterns of 7 year- olds from Generation XXI
Catarina Alexandra Moura Barbosa
M
2020
INFLUENCE OF PARENTAL CHILD-FEEDING PRACTICES ON DIETARY PATTERNS OF 7 YEAR-OLDS FROM GENERATION XXI
Catarina Alexandra Moura Barbosa
Orientadora: Prof. Doutora Andreia Oliveira
Instituto de Saúde Pública da Universidade do Porto Faculdade de Medicina da Universidade do Porto
Dissertação de candidatura ao grau de Mestre em Saúde Pública apresentada à Faculdade de Medicina e Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Portugal
Porto, 2020
Este trabalho foi realizado no âmbito do projeto Geração XXI, desenvolvido no Departamento de Epidemiologia Clínica, Medicina Preditiva e Saúde Pública da Faculdade de Medicina da Universidade do Porto e no Instituto de Saúde Pública da Universidade do Porto.
A sua realização só foi possível com a participação das crianças e famílias que aceitaram este desafio, às quais agradecemos a sua disponibilidade. O projeto contou com o apoio do Programa Operacional de Saúde-Saúde XXI, Quadro Comunitário de Apoio III (co-financiado pelo FEDER), Administração Regional de Saúde do Norte, Fundação Calouste Gulbenkian e Fundação para a Ciência e Tecnologia.
Os objetivos desta tese inserem-se nos projetos de investigação financiados por Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e Tecnologia através dos projetos: “Appetite regulation and obesity in childhood: a comprehensive approach towards understanding genetic and behavioral influences”
(POCI-01-0145-FEDER-030334; PTDC/SAL-EPI/30334/2017) and “Appetite and adiposity - evidence for gene-environment interplay in children” (IF/01350/2015).
Esta dissertação tem por base dois manuscritos nos quais colaborei na elaboração das hipóteses, análise e interpretação dos dados e fui responsável pela escrita das suas primeiras versões:
I. Association of early feeding practices with dietary patterns of 7-year-olds from the birth cohort Generation XXI.
II. May parental child-feeding practices at 4 years of age prospectively influence dietary patterns of 7 year-olds that explain body mass index later in life?
Agradecimentos
A todos aqueles que me ajudaram a conquistar mais uma importante etapa do meu percurso profissional.
À minha orientadora, Professora Doutora Andreia Oliveira,
Pela ajuda, orientação, pelo incentivo, pelo exemplo enquanto profissional da área, pela simpatia e disponibilidade sempre demonstrada!
À Alexandra Costa,
Pela simpatia e prontidão demonstrada em ajudar sempre que foi necessário!
Aos meus colegas do Mestrado,
Pelo companheirismo, momentos de partilha e apoio ao longo desta etapa académica!
À Cláudia, Margarida, Rita e Filipa,
Pela amizade, pela partilha ao longo dos anos e por me terem incentivado a seguir em frente!
Ao Pedro,
Pelo apoio constante, carinho, foram anos importantes de muito crescimento!
À minha família, em particular aos meus Pais e Avós Jorge e Maria,
Pelo incentivo, apoio constante, orgulho demonstrado e por acreditarem sempre nas minhas capacidades!
À Glorinha,
Por me ter iluminado o caminho quando este parecia difícil assim como me ter feito acreditar nas minhas capacidades!
Agradeço ainda às crianças e famílias que aceitaram participar no projeto Geração XXI e um obrigado ao Professor Doutor Henrique Barros e à Professora Doutora Ana Cristina Santos pela cedência dos dados.
Table of Contents
LIST OF TABLES ... vi
LIST OF ABBREVIATIONS ... vii
RESUMO ... 1
ABSTRACT ... 6
INTRODUCTION ... 10
1) Parental Child-Feeding Practices ... 10
1.2) Early-Feeding Practices ... 12
2) Children’s Dietary Patterns ... 14
3) Childhood Obesity as a Public Health concern ... 17
4) The relation between child-feeding practices and children’s dietary patterns – what this thesis adds? ... 19
AIMS ... 21
PAPERS ... 22
PAPER I ... 23
PAPER II ... 46
GENERAL DISCUSSION AND CONCLUSIONS ... 67
REFERENCES ... 71
LIST OF TABLES
Paper I
Table 1 – Children and their mothers’ characteristics, by sex……….43
Table 2 – Associations between the early feeding practices and the “Energy-dense foods” dietary pattern identified by Partial Least Squares at 7 years-old, explaining BMI z-scores at age 10……….44
Table 3 – Associations between the early feeding practices and the “Fish-based”
dietary pattern, identified by Partial Least Squares at 7 years-old………..45
Paper II
Table 1 – Characteristics of mothers and children from the Generation XXI birth cohort included in the study………..65
Table 2 – Association of parental child-feeding patterns at 4 years-old with the dietary patterns (“Energy-dense foods” and “Fish-based”) followed at 7 years of age, stratified by sex………66
LIST OF ABBREVIATIONS
AHEI – Alternate Healthy Eating Index BMI – Body mass index
CI – Confidence interval
CFQ – Child Feeding Questionnaire FFQ – Food frequency questionnaire HEI – Healthy Eating Index
MDS – Mediterranean Diet Score PCA – Principal component analysis PLS – Partial least squares
RRR – Reduced rank regression SD – Standard deviation
SPSS – Statistical Package for Social Sciences
RESUMO
Introdução
As primeiras experiências com os alimentos e as práticas parentais de controlo da alimentação das crianças podem influenciar o desenvolvimento das suas preferências alimentares e o estabelecimento de certos padrões alimentares. A maioria dos estudos explorou as associações entre as práticas parentais de controlo da alimentação em relação ao peso das crianças ou ao consumo de grupos alimentares específicos, em vez do estabelecimento de padrões alimentares mais tarde na vida. Este trabalho teve dois objetivos principais: i) avaliar se algumas práticas de alimentação precoce (amamentação e diversificação alimentar) estão associadas aos padrões alimentares de crianças de 7 anos (artigo I); ii) estudar a associação entre práticas parentais de controlo da alimentação infantil aos 4 anos de idade e padrões alimentares identificados aos 7 anos de idade explicativos dos z- scores do índice de massa corporal (IMC) mais tarde na vida (aos 10 anos de idade) (artigo II).
Métodos
Os participantes de ambos os estudos integram a coorte de nascimento de base populacional Geração XXI. Os participantes foram recrutados em todas as maternidades públicas da área metropolitana do Porto, entre 2005 e 2006 (8647 recém-nascidos e 8495 mães). Foram realizadas avaliações presenciais ao nascimento, 4, 7 e 10 anos de idade, e as informações foram recolhidas por entrevistadores treinados através de questionários estruturados e exames físicos. No início do estudo, foram obtidos dados sobre o sexo da criança, peso ao nascimento, idade gestacional, idade e escolaridade maternas. Aos 4 anos, dados sobre as práticas de alimentação de primeira infância, nomeadamente a existência de aleitamento materno, a idade e o primeiro alimento introduzido na diversificação alimentar foram reportados pelo principal cuidador da criança, geralmente as mães.
Outras práticas parentais de controlo da alimentação infantil foram avaliadas aos 4 anos através do Child Feeding Questionnaire (CFQ), adaptado e validado para ser
aplicado a pais de crianças portuguesas em idade pré-escolar. Três padrões de práticas parentais de controlo da alimentação foram identificados por análise de componentes principais: Monitorização Percebida (que inclui as dimensões de monitorização, responsabilidade percecionada e controlo percecionado); Restrição (inclui o controlo encoberto, restrição e preocupação com o peso da criança) e Pressão para Comer (inclui a pressão para comer e o controlo percecionado). Aos 7 anos, o consumo alimentar habitual foi avaliado por um questionário de frequência alimentar validado, relativo aos 6 meses anteriores, aplicado por entrevistadores treinados ao principal cuidador da criança. Num trabalho anterior, dois padrões alimentares foram identificados por Partial Least Squares (PLS), um método híbrido que deriva padrões alimentares baseados na máxima variância explicada pelas variáveis preditoras (grupos de alimentos aos 7 anos de idade) e as variáveis de resposta (z-scores do IMC aos 10 anos). O primeiro padrão alimentar foi significativamente associado ao z-score do IMC aos 10 anos de idade e foi caracterizado pelo consumo de carnes processadas, alimentos densamente energéticos e refrigerantes e baixo consumo de sopa de legumes, sendo denominado “Energy-dense foods”. O segundo padrão alimentar foi caracterizado por uma maior ingestão de peixe e menor consumo de alimentos com elevada densidade energética, sendo denominado de “Fish-based”, sem associação com o IMC das crianças.
Parâmetros antropométricos, como peso e estatura, foram medidos por observadores treinados de acordo com procedimentos padronizados e o z-score do IMC foi calculado de acordo com os critérios da Organização Mundial de Saúde, aos 7 e 10 anos.
No artigo I, modelos lineares generalizados foram calculados para avaliar a associação entre as práticas de alimentação de primeira infância e os padrões alimentares (confundidores: idade e escolaridade maternas, IMC pré-concecional e prática de atividade física aos 7 anos de idade). A amostra final incluiu 3673 crianças com dados completos sobre as variáveis de interesse.
No artigo II, modelos de regressão linear multivariada foram realizados para estimar as associações entre as práticas parentais de controlo da alimentação das
maternas, IMC pré-concecional, IMC aos 4 anos e prática de atividade física aos 7 anos de idade (n = 3272).
Para ambos os artigos, coeficientes de regressão β̂ com intervalos de confiança a 95% (IC95%) foram calculados. Foram testadas interações do sexo da criança nas associações em estudo e realizadas análises estratificadas. A análise estatística foi realizada por meio do software Statistical Package for Social Sciences 25.0 (SPSS®, Inc., 2017).
Resultados Artigo I
Em análise multivariada, as raparigas amamentadas exclusivamente entre ≥3 a <5 meses e os rapazes entre ≥5 a <6 meses de idade obtiveram pontuações significativamente mais altas no padrão alimentar "Fish-based" aos 7 anos, em comparação com crianças que nunca foram amamentadas ou amamentadas exclusivamente por menos de 3 meses (Raparigas: β̂=0,172; IC95%: 0,029; 0,316;
Rapazes: β̂=0,308; IC95%: 0,074; 0,514). Crianças com maior duração de aleitamento materno também apresentaram uma maior probabilidade de seguirem o padrão alimentar “Fish-based” aos 7 anos (≥3 a <5 meses - somente em rapazes: β̂=0,271;
IC95%: 0,038; 0,504; ≥6 meses – em rapazes e raparigas: β̂=0,219; IC95%: 0,077;
0,361; β̂=0,223; IC95%: 0,088; 0,358, respectivamente) em comparação com crianças nunca amamentadas ou amamentadas não exclusivamente por menos de 3 meses.
Crianças que iniciaram a diversificação alimentar pelos cereais, apresentaram pontuações mais baixas no padrão alimentar “Energy-dense foods” em comparação com crianças que iniciaram com sopa (Rapazes: β̂= -0,183; IC95%: -0,292; -0,074;
Raparigas: β̂= -0,155; IC95%: -0,259; -0,050), contudo apenas as raparigas tiveram maior probabilidade de seguirem o padrão alimentar “Fish-based” aos 7 anos de idade (β̂= 0,137; IC95%: 0,006; 0,267).
Artigo II
Em análise multivariada, raparigas cujos pais usaram mais práticas de Restrição, Monitorização e Pressão para Comer aos 4 anos de idade apresentaram menor probabilidade de seguir o padrão alimentar “Energy-dense foods” aos 7 anos,
mas apenas em raparigas (β̂=-0,082; IC95%: -0,134; -0,029; β̂=-0,093; IC95%: -0,146;
-0,039; β̂= -0,079; IC95%: -0,135; -0,024, respetivamente). Crianças de ambos os sexos, cujos pais usaram mais Restrição e Monitorização, apresentaram maior probabilidade de aos 7 anos de idade seguirem o padrão alimentar “Fish-based”
(Raparigas: β̂=0,143; IC95%: 0,077; 0,210; β̂=0,079; IC95%: 0,011; 0,148; Rapazes:
β̂=0,157; IC95%: 0,090; 0,224; β̂=0,104; IC95%: 0,041; 0,168), enquanto a Pressão para Comer apresentou uma associação inversa com este padrão alimentar (Raparigas: β̂=-0.100; IC95%: -0,170; -0,030; Rapazes: β̂=-0,083; IC95%: -0,153; - 0,013).
Conclusão
A amamentação exclusiva por ≥3 a <6 meses de idade parece relacionar-se com uma maior probabilidade de seguir um padrão alimentar mais saudável em idade escolar. Durações mais longas de aleitamento (exclusivo ou não) também aumentaram a adesão ao padrão alimentar saudável. O tipo de alimento introduzido pela primeira vez na diversificação alimentar mostrou estar mais consistentemente associado aos padrões alimentares das crianças comparativamente à idade da diversificação alimentar.
As práticas de Restrição, Monitorização e Pressão para Comer aplicadas a crianças de 4 anos diminuíram a probabilidade dessas crianças seguirem um padrão alimentar relacionado com a obesidade anos depois, mas apenas em raparigas.
Crianças, cujos pais aplicaram mais Restrição e Monitorização aos 4 anos de idade apresentaram maior probabilidade de seguirem um padrão alimentar caracterizado por um maior consumo de peixe e consumo inferior de alimentos de elevada densidade energética 3 anos mais tarde, enquanto a Pressão para Comer apresentou uma associação inversa.
Este trabalho enfatiza a importância de fornecer orientações aos pais sobre amamentação, diversificação alimentar e também o efeito potencial de certas práticas parentais de controlo da alimentação infantil na formação dos padrões alimentares das crianças.
Palavras – chave: Aleitamento materno; Diversificação alimentar; Comportamento alimentar; Alimentação; Exposição alimentar; Crianças; Estudos de coorte
ABSTRACT
Introduction
Early feeding experiences and parental child-feeding practices can influence food preferences and the establishment of certain dietary patterns. Most studies have explored the associations between parental feeding practices in relation to the weight status of children or the children’s consumption of specific food groups, rather than the establishment of dietary patterns later in life. This work has two main objectives: i) to evaluate whether some early feeding practices (breastfeeding and complementary feeding) are associated with dietary patterns of 7 year-olds (paper I); ii) to study the association between parental child-feeding practices at 4 years of age and dietary patterns identified at 7 years-old that explain body mass index (BMI) z-scores later in life (at age 10) (paper II).
Methods
Participants in both studies are from the population-based birth cohort Generation XXI. Participants were recruited from all public maternity hospitals from Porto metropolitan area, between 2005 and 2006 (8647 newborns and 8495 mothers). Face-to-face evaluations at birth, 4, 7 and 10 years of age were performed, and information was collected by trained interviewers through structured questionnaires and physical examinations. At baseline, data on child’s sex, birth weight, gestational age and maternal age and education were obtained. At 4 years-old, data on early feeding practices, namely exclusive and any breastfeeding duration, timing of introduction to complementary feeding and first food introduced to the child, were reported by the main caregiver, usually mothers. Other parental child-feeding practices were evaluated at 4 years-old through the Child Feeding Questionnaire (CFQ), adapted and validated to be applied to parents from pre- school Portuguese children. Three parental child-feeding patterns were derived, by Principal Component Analysis (PCA): Perceived Monitoring (which includes the dimensions of monitoring; perceived responsibility and overt control); Restriction
Pressure-to-eat (includes pressure-to-eat and overt control). At 7 years-old, habitual diet was assessed by a validated food frequency questionnaire, covering the previous 6 months, applied by trained interviewers to the main caregiver of the child. In a previous work, two dietary patterns were derived by Partial Least Squares (PLS), a hybrid method that derives dietary patterns based on the maximum variance of the predictor variables (food groups at 7 years-old) and response variables (BMI z- score at 10 years-old). The first pattern was significantly associated with WHO BMI z- scores at 10 years-old and was characterized by processed meats, energy-dense foods and soft drinks and low consumption of vegetable soup, named as “Energy- dense foods”. The second derived pattern was characterized by higher fish intake and lower in energy-dense foods – “Fish-based” dietary pattern, with no association with children’s BMI.
Anthropometrics, namely weight and height, were measured by trained staff according to standardized procedures and the BMI z-score was calculated according to the World Health Organization criteria, at 7 and 10 years-old.
In paper I, generalized linear models were used to assess the association between early feeding practices and the dietary patterns (covariates: maternal age, education, BMI before pregnancy and child’s physical activity at 7 years-old) The final sample included 3673 children with complete data on the variables of interest.
In paper II, multivariate linear regression models were run to estimate the associations between parental child-feeding practices and the dietary patterns, after adjustment for maternal age, education, BMI before pregnancy, BMI at 4 years of age and child’s physical activity at age 7 (n = 3272).
For both Paper I and Paper II, β̂-regression coefficients with 95% confidence intervals (95%CI) were calculated, and sex-interactions were tested and stratified analyses were further conducted. Statistical analysis was performed using the Statistical Package for Social Sciences 25.0 software (SPSS®, Inc., 2017).
Results Paper I
In multivariate analysis, girls exclusively breastfed between ≥3 to <5 months and boys between ≥5 to <6 months of age had significantly higher scores in the
“Fish-based” dietary pattern at 7 years-old, compared to those never breastfed or exclusively breastfed for less than 3 months (Girls: β̂=0.172; 95%CI:0.029; 0.316;
Boys: β̂=0.308; 95%CI:0.074; 0.514). Children with longer duration of any breastfeeding had also a higher likelihood of following the “Fish-based” dietary pattern at age 7 (≥3 to <5 months – only in boys: β̂=0.271; 95%CI:0.038; 0.504; 6 months – in boys and girls: β̂=0.219; 95%CI:0.077; 0.361; β̂=0.223; 95%CI:0.088;
0.358, respectively) compared with those never breastfed or non-exclusively breastfed for less than 3 months. Children who started the complementary feeding by cereals porridge, presented lower scores in the “Energy-dense foods” dietary pattern compared with those starting with soup (Boys: β̂=-0.183; 95%CI:-0.292; - 0.074; Girls: β̂=-0.155; 95%CI:-0.259; -0.050), but only girls had higher scores in the
“Fish-based” dietary pattern (β̂=0.137; 95%CI:0.006; 0.267).
Paper II
In multivariate analysis, girls whose parents used more Restriction, Monitoring and Pressure-to-eat at 4 years of age had a lower likelihood of being following the “Energy-dense foods” dietary pattern at 7 years-old, but only in girls (β̂=-0.082; 95%CI:-0.134; -0.029; β̂=-0.093; 95%CI:-0.146; -0.039; β̂=-0.079; 95%CI:- 0.135; -0.024, respectively). Children of both sexes, whose parents use more Restriction and Monitoring showed to have a higher likelihood of following the “Fish- based” dietary pattern (Girls: β̂=0.143; 95%CI:0.077; 0.210; β̂=0.079; 95%CI:0.011;
0.148; Boys: β̂=0.157; 95%CI: 0.090; 0.224; β̂=0.104; 95%CI: 0.041; 0.168), while Pressure-to-eat showed the inverse association (Girls: β̂=-0.100; 95%CI:-0.170; - 0.030; Boys: β̂=-0.083; 95%CI: -0.153; -0.013).
Conclusions
Exclusive breastfeeding for ≥3 to <6 months of age may be related with an increased likelihood of following a healthier dietary pattern at school age. Longer durations of any breastfeeding also increased the adherence to the healthy dietary pattern. The type of food firstly introduced at complementary feeding rather than age of introduction, was more consistently associated with children’s dietary
Restriction, Monitoring and Pressure-to-eat applied by parents to 4 years-old children decreased the likelihood of those children being following an obesity- related dietary pattern there years later, but only in girls. At the same time, children of both sexes, whose parents use more Restriction and Monitoring showed to have a higher likelihood of following a dietary pattern high in fish and low in energy-dense foods, while Pressure-to-eat showed the inverse association.
This work emphasizes the importance to provide guidance to parents about breastfeeding, complementary feeding and also the potential effect of certain parental child-feeding practices in shaping dietary patterns of young children.
Keywords: Breastfeeding; Weaning; Feeding behaviour; Diet; Dietary exposures;
Children; Cohort studies
INTRODUCTION
1) Parental Child-Feeding Practices
Parents and other caregivers are important role models with potential in shaping child’s eating behaviours. They are responsible to provide the child’s first food learning experiences, then controlling what, when and how much they eat (1- 3). Feeding children is a reciprocal process that not only depends on the child but also on the abilities of the parents (4). The child should be allowed to have autonomy over eating, in terms of initiating and stopping eating depending on his/her hunger and satiation (3). However, parents should also give support and boundaries around food, as well as control the availability and accessibility of food in the context of the family environment (3, 5, 6). In the history of the human evolution, situations as food scarcity and infectious diseases influenced the parental child-feeding practices and some of those traditional practices have been passed through generations in order to protect the children’s health (7). Nowadays, we are facing an increased availability of palatable and inexpensive energy-dense foods that affects our relation with foods and consequently the parental feeding practices (8).
The specific feeding practices used to improve the quantity and/or quality of the food eaten by the child are: Restriction, that consists in regulating the type and amount of foods consumed; Monitoring that is the degree to which a parent keeps track of what and how much the child eats; Pressure-to-eat that is an attempt to improve the quantity or quality of the child’s food intake (6, 9, 10). Among the methods of feeding control there is a distinction between Overt and Covert control;
whereas Overt control corresponds to a firm behaviour of the parents (perceived by the child) about what should be eaten, and the Covert control is a restriction of less healthy foods, in a way not perceived by the child itself, mainly through the modification of the food environment (11). A previous study pointed out for the complexity of the parental child-feeding attitudes and practices assessment, namely showing that restriction is associated with maternal perception and concern with the
to be associated with responsibility (10) and overt control (11). Also, overt control is positively associated with pressure-to-eat (11). In this sense it is easily to analyse the approach based on parental child-feeding practices instead of evaluating single dimensions (12).
The parental child-feeding practices are also motivated by the goals that parents set for their children, which are in turn influenced by children’s individual characteristics (age, sex, weight status and eating behaviour) (7). Despite being well intentioned, growing evidence suggests that certain parental child-feeding practices may compromise the development of children’s food preferences, dietary intake, diet quality, growth and weight status (7, 13).
Among the controlling feeding practices, for instance, the Pressure-to-eat results from a parental response to concerns about the child’s low weight (10, 14).
Usually these outcomes are the opposite of the parent’s intentions, with the pressured foods being consumed and preferred less and the restricted foods being consumed and preferred more (15, 16). In addition, these highly restrictive feeding practices were also associated with eating in the absence of hunger (17), interfering with the children’s ability to self-regulate energy intake which can promote overweight (18). However what makes difficult to establish the relation between parental child-feeding practices and child’s BMI is the existence of a bidirectional relation (4, 9). A study that examined the bidirectional association between the practices of restriction, monitoring, pressure-to-eat, and overt and covert control with child’s BMI at 4 and 7 years old found that parents tend to apply restriction, covert control and pressure-to-eat in response to their child’s BMI (4).
Children learn about food through observation of the eating behaviours of parents or peer models. Children show better acceptance to taste unfamiliar foods when they observe adults eating those foods (19). In this sense, considering the home environment, parents and siblings strongly predict the development of the children’s eating behaviours which could impact on the parental feeding practices (20). Additionally, there is evidence that parents’ own BMI and weight concerns’ also could influence the use of controlling feeding practices over their child (21-23).
1.2) Early-Feeding Practices
Child feeding practices begin early in life, with breastfeeding/formula and complementary feeding. Breastfeeding has several health benefits, not only to the development and future health of the infant, but also to mother’s health (24). Breast milk is a good source of immune-related components and biologically active substances that protect infants against infections (24). Recommendations are for exclusive or full breastfeeding promoted at least for 4 months of age and exclusive or predominant breastfeeding approximately for 6 months of age (25). From 6 months onwards, breastfeeding should be promoted but in combination with other foods for 2 years or longer (26-28).
Observational studies have been associated breastfeeding with consistent protective effects against later childhood obesity when compared with feeding infant formula (29-31). However, some systematic reviews have found inconsistent results about whether the duration of breastfeeding is a protective factor of overweight and obesity later in life (32, 33). It has also been proposed that breastfed infants show the ability to self-regulate their caloric intake, adjusting the quantity of milk consumed. As so, bottle-fed infants are consuming larger volumes (more calories) and present more rapid weight gain and growth than breastfed infants (34- 36). Mothers of formula-fed infants can control the volumes consumption and even encourage their infants to finish the quantities remaining in the bottle, which can result in overfeeding (37). Breastfeeding appears to lead to better appetite and satiety regulation with the breastfed infants having a more active role in controlling the amount of milk consumed, without the interference of the mother (7, 38, 39).
Infants are born with a biological predisposition to prefer sweet and avoid bitter and sour tastes (25, 40), while preferences for salt seem to appear approximately at 4 months of age (41). An observational study identified the existence of an universal preference for sweet tastes, through the facial expressions manifested by the infants, as well as their aversion for sour or bitter tastes (13).
These predispositions are derived from an evolutionary process in which sweetness encourages the consumption of energy-dense foods, which was more advantageous in energy scarce situations (42). On the other hand, the sourness or bitterness
trimester of gestation and infants are exposed to different tastes in utero, when the flavours from the mother’s diet are transmitted to the amniotic fluid and continues with milk feeding and also through complementary feeding with the introduction to different solid foods (44, 45). In this sense, breastfed infants are exposed to a greater variety of tastes, whereas the formula fed infants have little variation.
Then it comes a period of transition between breast or formula milk to complementary foods for both nutritional and developmental reasons (25, 26). This is a phase of rapid growth, when infants are susceptible to nutrient deficiencies and excesses, in which diet with new exposures appears to have a great effect on the development of flavours and food preferences (46). Recommendations support that complementary foods should not be introduced before 4 months of age, but should also not be delayed beyond 6 months of age (25, 47, 48). Moss et al. found that children between 2 and 4 years old have higher risk of overweight if they were introduced to complementary feeding before 4 months of age (49). Besides the timing of complementary feeding, the sensory and motor experiences associated with the type, variety, smells and textures of foods contribute for later food acceptance and preferences (50). As mentioned elsewhere, predetermined preferences and taste experiences that occur in utero and later during breastfeeding can affect the infant’s acceptance of solid foods (51). A longitudinal randomized control trial, where the participants were randomly assigned to a repeatedly fed one vegetable (intervention arm), revealed that the initial consumption of vegetables did not differ between the breastfed and formula-fed infants, however the breastfed infants increased their intake more rapidly, showing to consume significantly more vegetables after ten exposures (52). Another longitudinal study found that the existence of breastfeeding and early experiences with vegetables variety during complementary feeding promote the acceptance of new vegetables into childhood (53). These findings suggest that early exposures with flavours in breast milk can modify the infants’ acceptance of certain foods and have potential benefits for the adult dietary pattern (54).
Overall, it seems that parents and caregivers could not alter their infants’
innate preferences, but they may be able to modify subsequent preferences by repeated early exposures to vegetables, instead of sweet food (40). If this is not
accomplished, infants will probably continue to have more access to sweet foods (40). The window for introducing new tastes and textures is small (51), and infants usually become neophobic at 2 years old and at this age they may be less willing to accept new foods (55). That’s why the repeated and early exposure to a variety of food, such as vegetables, is important (44). This is in line with the recent recommendations that supports that parents should be encouraged to introduce vegetables as the first food in the complementary feeding (56).
2) Children’s Dietary Patterns
Eating habits are established early in life, and result from a complex interaction between several factors and seem to track into childhood and adulthood, with last longing effects (57). Diet, which results in a complex network of foods and nutrients, represents an important influence on our health, and can also prevent the development of disease (58). However, due to the complex effects of diet, it is difficult to understand the role of individual foods or nutrients in isolation (58).
Foods are consumed together, so these combinations result in complex antagonistic and synergistic effects (59-61). In the last years, nutritional epidemiology has focused on the study and analysis of dietary patterns, since they provide a more informative way of relating diet with health outcomes comparing to the reductionist approach of studying single nutrients or foods (59, 62, 63). As so, dietary patterns are described as the quantities, proportions, variety or combination of different foods, drinks and nutrients in a diet (64). The analysis of dietary patterns could have greater public health significance since their interpretation would be more easily translated to the general public (63). In addition, dietary patterns emphasise on foods rather than on specific nutrients for which food sources may be unfamiliar to many consumers (64). A review highlighted that the dietary pattern analyses may better clarify obesity risk than looking at individual nutrients or foods as obesity has several diet-related determinants. The authors also suggests that diets high in energy-dense, high-fat and low-fibre foods predispose young people to later obesity (65). There is some evidence that following certain dietary patterns characterized by
higher intake of vegetables, fruits, whole grains and low consumption of red and processed meats, sugar-sweetened food and drinks has positive health outcomes (64).
Dietary patterns can be defined by different methodological approaches.
There are a priori, a posteriori and hybrid methods to derive dietary patterns (59, 60). Hypothesis-driven methods (a priori) evaluate food quality using indexes or scores systems to classify individuals based on their adherence to dietary guidelines or specific dietary habits for a healthy diet or diets known to be healthy (59, 66, 67).
The Healthy Eating Index (HEI), the Alternate Healthy Eating Index (AHEI) and the Mediterranean Diet Score (MDS) are examples of a priori scores (68). Constructing scores and indices based on food/nutritional guidelines or recommendations is a useful method to evaluate the magnitude of the effects of dietary recommendations on disease outcomes (69). There are multiple ways to derive diet quality scores, all of which tend to encourage the consumption of fruits, vegetables and whole grains (70). Considering potential limitations of this method, some indices or scores were adapted from the original versions in an attempt to integrate the country-specific dietary recommendations and this makes difficult to compare results between several studies (60, 68). In addition, the majority of the dietary indices are inappropriate to be used in studies conducted among children, because they have been developed based on dietary recommendations created to be followed by adults (71). In this sense, the use of these methods in population samples of children is scarce (72). Another limitation is that the definition of dietary indices requires the existence of dietary guidelines (58).
On the other hand, a posteriori methods, such as factorial analysis, cluster analysis and principal component analysis (PCA), try to explain the maximum variance among the predictor variables (food consumption) (67). These techniques use the actual data to derive dietary patterns, but ignore prior information of nutrient and disease relations (62). This empirically derived dietary patterns have the strength of being independent of definitions about what is a healthy pattern, but on the contrary the translation of the identified dietary patterns to the individual level is much more difficult to accomplish (73, 74).
More recently, hybrid methods have been proposed to derive dietary patterns. They consist of statistical techniques such as Reduced Rank Regression (RRR) and Partial Least Squares (PLS), and combine a priori information with exploratory statistics (59). The hybrid approach uses predictor variables that are relevant for the purpose of the researcher, and at the same time, response variables (74). RRR seeks to derive dietary patterns to explain the variance of response variables, namely represented by important nutrients or biomarkers in the target condition (59, 63). This method, contrary to PCA, does not focus on explaining variance among foods, plus have the advantage of incorporating information on biological pathways (67). As a limitation, the RRR needs the availability of response information (58) and if the knowledge about the biologic mechanisms remains to be explained, this method cannot be used (62). On the other hand, PLS is a recent technique for deriving dietary patterns (59) and an intermediate method between PCA and RRR, since the derived dietary patterns explained simultaneously the maximum variance of both the predictor variables (foods) and the response variables (a given health outcome, such as body mass index) (63). PLS is hypothesized as a more advantageous method, since it considers the biochemical pathways in which dietary patterns may influence health (74). This method has been used in some studies relating dietary patterns with bone health (63, 75) and also myocardial infarction (76), however little body of evidence exists regarding its use in relation to obesity (59).
Dietary patterns that are derived from hybrid methods are particularly strong and important to the population as they relate to specific health outcomes, whereas a priori methods create patterns with little applicability in populations. On the other hand, derived patterns by a posteriori methods, are less relevant to health (74). In this way, all approaches have advantages and limitations (74), and despite their similarities in terms of the mathematical foundations, studies have reported different recommendations about their applicability (75).
3) Childhood Obesity as a Public Health concern
Obesity is a condition defined as abnormal or excessive accumulation of fat that might impair health (77). Childhood obesity rates have been growing worldwide (78). Globally in 2016, 340 million children and adolescents (aged 5 to 19 years-old) and around 40 million children (aged bellow 5 years-old) were considered overweight or obese (79). Additionally, the number of overweight children shows an increase in almost all lower and middle-income countries (80). This current trend is opposite to what initially has been observed, since obesity was once considered a problem of high-income countries (79) (79). In result, the world’s population is experiencing a co-existence of both overweight/obesity and underweight, where the first ones are responsible for more deaths than the second condition (81). In Portugal, childhood obesity and overweight have the highest prevalence rates among the Europe (82, 83). According to the latest data on the National Food, Nutrition and Physical Activity Survey 2015-2016, conducted in a representative sample of the Portuguese general population, 22.3% and 34.8% were the percentages of obese and overweight population respectively (84). In addition, 7.7%
of the children under 10 years-old were obese and 17.3% of the children were overweight (84). Also, data from the European Childhood Obesity Surveillance Initiative (COSI), which uses cross-sectional nationally representative samples of primary-school children, found the highest overweight and obesity prevalence between the countries from Southern Europe (Italy, Greece, Spain and Portugal) (85).
The development of obesity is likely derived from an energy intake that exceeds the energy requirements, and consequently the energy expenditures which results in an energy imbalance (80). Despite this basic principle, childhood obesity is a much more complex issue and its causes are multi-faceted (78). The evolutionary changes that occurred in the development of dietary patterns culminate in an increased consumption of energy-dense foods, high in fat and sugars. The effects of the industry marketing along with lower levels of physical activity are also pointed out as important contributors to the rise in obesity (81). In addition, the new
lifestyles result in increased time spent in the workplace (86) and consequently parents have less time available for cooking meals at home (87).
An excessive weight gain in childhood is associated with an increased likelihood of developing hypertension, metabolic disorders and can also originate in the short-term poor self-esteem, eating disorders and depression (88, 89). In this way, a study concluded that children with obesity may require special support at school (90). Childhood obesity is of particular concern because represents a strong predictor for obesity in adulthood (88). Being overweight and obese is linked to an increased risk of many non-communicable diseases (NCDs) such as diabetes, coronary heart disease, stroke and cancers, (89, 91) that are presented as the leading causes of death worldwide (81). In 2014, 5% of the worldwide deaths were attributed to obesity (92). The forecasts by 2025 point out that global obesity prevalence will reach 18% in men and exceed 21% in women and an estimation of 205.5 million children and adolescents (5-19 years-old) will be affected (79).
Obesity is largely preventable, and despite the growing evidence on its consequences, there are countries that present different political and economic contexts and a lack of alignment in terms of the health approach, meaning that childhood obesity is not faced as a public health priority (79). The global economic impact of obesity-related diseases is rising with both direct (medical expenses) and indirect losses (absenteeism, reduced quality of life) in all age groups (93). Childhood is seen as a critical period in terms of facing the problematic of obesity (94) and in the establishment of healthy behavioural patterns (95).
To improve children’s nutrition it is necessary to invest on sustained and effective multi-sectoral nutrition programmes over the long term (80), involving government, community leaders, schools, health professionals and the industry (78).
However, first it is necessary to understand which risk factors are involved in the aetiology of childhood overweight and can effectively be addressed. The development of childhood overweight can be the effect of the intercorrelation of some factors from multiple contexts which can be conceptualized through an ecological approach (6). This model consists in three principal domains capable of influencing the child’s weight status, which are the community and demographic
(household level); and the child’s behaviour (individual level) (6). The community level is the most distal domain of the three, because represents the socioeconomic status, the accessibility of foods and restaurants, the neighbourhood safety and ethnicity (6). Parents characteristics are related to the type of food available at home, the parent’s eating and physical activity, also their weight status, the nutritional knowledge and their interest and promotion of healthy principles (6). The child’s behaviour, also known as the more proximal domain, relates to the food habits, practice of physical activity and time spend on leisure activities by the child (6).
Despite the need for preventive actions is increasingly acknowledged, the path to prevent childhood obesity in complex and need to be evidence-based, systematic and stakeholder-informed (96).
4) The relation between child-feeding practices and children’s dietary patterns – what this thesis adds?
Parental child-feeding practices can either limit or expand the acquisition of a certain dietary pattern (40), and the first 2 years of life have been described as having the potential to influence dietary patterns at school-age (97). Since birth, parents play a central role on their children’s dietary patterns and this influence remains until they become exposed to other dietary influences available in school and also in the community (64).
Previous evidence have explored the relationship of early feeding practices with dietary patterns, suggesting a healthier dietary pattern in those children who were breastfed (56, 98, 99) and introduced to complementary feeding after 4 months of age (100). Breastfeeding has been suggested to have possible health benefits in later childhood; a study suggests that when breastfeeding occurred for shorter durations, children were at greater dietary risk (101). The majority of studies have explored the association of “ever breastfed” which includes simultaneously exclusive and non- exclusive breastfeeding in relation to children’s diet (102). Our study examined the individual effects of both the exclusive and non-exclusive breastfeeding duration in
the establishment of dietary patterns in later years. In addition, our study also explored the type of food first introduced at the complementary feeding in relation to the dietary patterns at 7 years-old, which is less examined in the literature. It has been described on previous studies, a relationship between breastfeeding and later consumption of vegetables. A higher intake of this type of food, as a part of a healthy dietary pattern, is associated with a reduced risk of diseases as well as the development of obesity (103, 104). However, the association of such feeding practices with dietary patterns explaining a specific outcome such as children’s BMI is less understood.
The relation of other parental child-feeding practices, such as restrictive or more monitoring practices with the establishment of dietary patterns in school-aged children is also under research. Most studies explored their relation with specific food consumption groups or children’s BMI. Research on this topic is scarce; one cohort study found that parents who used higher pressure-to-eat had children with more unhealthy diet and that restriction was associated with less unhealthy dietary patterns (105).
AIMS
The specific objectives of this thesis are described below and are presented by papers.
Paper I
To evaluate the association of early life feeding practices (breastfeeding duration; timing of exclusive and non-exclusive breastfeeding; age and type of complementary feeding) with dietary patterns identified at 7 years-old that explain BMI z-scores later in life (at age 10).
Paper II
To explore the prospective effect of parental child-feeding practices at 4 years of age in dietary patterns identified at 7 years-old that explain BMI z-scores later in life (at age 10).
PAPERS
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PAPER I
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Association of early feeding practices with dietary patterns of 7-year-olds from the birth cohort Generation XXI.
Catarina Barbosa1; Alexandra Costa1; Andreia Oliveira1,2
1 EPIUnit - Instituto de Saúde Pública da Universidade do Porto [Institute of Public Health of the University of Porto], Rua das Taipas nº135, 4050-600 Porto, Portugal.
2 Departamento de Ciências da Saúde Pública e Forenses e Educação Médica da Faculdade de Medicina da Universidade do Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal.
Corresponding author:
Andreia Oliveira
EPIUnit - Instituto de Saúde Pública da Universidade do Porto
Rua das Taipas, 135 4050-600 Porto, Portugal [acmatos@ispup.up.pt]
Funding: Generation XXI was funded by the Health Operational Programme – Saúde XXI, Community Support Framework III and the Regional Department of Ministry of Health. This study was supported through FEDER from the Operational Programme Factors of Competitiveness – COMPETE and through national funding from the Foundation for Science and Technology – FCT (Portuguese Ministry of Education and Science) under the projects “Appetite regulation and obesity in childhood: a comprehensive approach towards understanding genetic and behavioural influences”
(POCI-01-0145-FEDER-030334; PTDC/SAU-EPI/30334/2017); “Appetite and adiposity - evidence for gene-environment interplay in children” (IF/01350/2015), and through the Investigator Contract (IF/01350/2015 - Andreia Oliveira). It had also support from the Calouste Gulbenkian Foundation.
The authors gratefully acknowledge the families enrolled in Generation XXI for their kindness, all members of the research team for their enthusiasm and perseverance and the participating hospitals and their staff for their help and support. We also acknowledge the support from the Epidemiology Research Unit (EPI-Unit: UID- DTP/04750/2013; POCI-01-0145-FEDER-006862).
Abstract
Background: Early feeding practices can influence food habits formation and later health. Previous studies have explored the associations between early feeding practices and child’s body mass index (BMI), however their role in the establishment of dietary patterns later in life is less understood.
Objective: To examine the association of early life feeding practices (breastfeeding duration; timing of exclusive and non-exclusive breastfeeding; type of foods and timing of complementary feeding) with dietary patterns identified at age 7, related with BMI z-scores at 10 years-old.
Methods: Participants are children from the population-based birth cohort Generation XXI, with data collected at baseline (2005/2006), 4, 7 and 10 years-old. Early feeding practices (breastfeeding and complementary feeding) were reported by the main caregiver, usually mothers, in face-to-face-interviews conducted by trained researchers. At 7 years-old, dietary intake was assessed with a validated food- frequency questionnaire (38 items/food groups). Two dietary patterns were previously derived by Partial Least Squares: the “Energy-dense foods” dietary pattern (high in energy-dense foods, processed meats and low in vegetable soup) and the “Fish-based”
dietary pattern (high in fish consumption and low in energy-dense foods). The first one was significantly associated with WHO BMI z-score at 10 years-old. Associations, by sex, were estimated by generalized linear models (β̂ regression coefficients and 95%
confidence intervals (95%CI)), adjusted for maternal age, education, BMI before pregnancy, and regular physical activity at age 7 (final sample n=3673).
Results: In boys, exclusive breastfeeding duration between ≥5 to <6 months of age was positively associated with the “Fish-based” dietary pattern, compared with those never breastfed or exclusively breastfed for less than 3 months (β̂=0.308; 95%CI:0.074;
0.541). In girls, the same association was found for those exclusively breastfed between ≥3 to < 5 months (β̂=0.172; 95%CI:0.029; 0.316). Children with longer durations of any breastfeeding had a higher likelihood of following the “Fish-based”
dietary pattern at age 7 (≥3 to < 5 months - only in boys: β̂=0.271; 95%CI:0.038; 0.504;
≥6 months - in boys and girls: β̂=0.219; 95%CI:0.077; 0.361; β̂=0.223; 95%CI:0.088;
0.358 respectively, compared with never breastfed or non-exclusively breastfed for
in comparison with soup, presented lower scores in the “Energy-dense foods” dietary pattern (Boys: β̂=-0.183; 95%CI:-0.292; -0.074; Girls: β̂=-0.155; 95%CI:-0.259; -0.050), but only girls presented higher scores in the ‘Fish-based’ dietary pattern (β̂=0.137;
95%CI:0.006; 0.267). The age of introduction of complementary feeding was not significantly associated with the dietary patterns of 7 year-olds, after adjusting for the potential confounders.
Conclusions: Exclusive breastfeeding for ≥3 to <6 months of age seems to increase the likelihood of a healthier dietary pattern at school age. Longer durations of any breastfeeding also increased the adherence to the healthier dietary pattern. The type of food at complementary feeding, rather than age of introduction, was more consistently associated with children’s dietary patterns. Parents should be properly advised on breastfeeding and complementary feeding has they have a critical role in shaping dietary patterns of young children.
KEYWORDS: Breastfeeding; Complementary feeding; Feeding behaviour; Cohort Studies; Diet; Children
Introduction
The early formation of food habits is recognized as an important key factor for children’s growth and development (1-4). Childhood obesity is of public health concern worldwide, and there is some evidence that the risk of obesity is predicted by early life exposures, such as the first feeding experiences (1, 2).
The World Health Organization (WHO) recommends exclusive breastfeeding during the first six months of life and, beyond that, a combination with complementary feeding until at least two years of age (5, 6). The 2017 guidelines of the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) stands that exclusive or full breastfeeding should be promoted for at least the beginning of the 5th month of life, and the desired goal is predominant breastfeeding until 6 months of age (7). Breastfeeding has several potential health benefits including a protective role for later obesity (8). Three meta-analyses supported this hypothesis, showing a significant protective effect of breastfeeding against overweight, however another meta-analysis showed no effect of breastfeeding on body mass index (BMI) after adjustment for confounding factors (9, 10).
The relationship between the time of introduction of complementary foods and childhood obesity is not completely clear. One systematic review found no consistent association between the timing of introduction of complementary feeding and childhood obesity (11), while other three (9, 10, 12) found that introducing foods before 4 months of age increased later childhood obesity risk. The type of food first introduced has been also associated with later food preferences (12). Infants show an innate preference for sweet tastes (13) and the introduction of sweet foods during the complementary feeding period may create an expectation that food should taste sweet and may lead to a higher rejection of foods with a bitter or sour taste, such as fruit and vegetables (14-16).
The relationship between early feeding practices and childhood obesity may be explained by the mediation role of children’s dietary patterns which have been shown to track from early childhood up to adulthood (16-18). Exclusive breastfeeding for less than 3 months was related to an unhealthier dietary pattern, low in fruits and
vegetables and high in snacks and treats, at 6 years of age (3). On the other hand, longer duration of breastfeeding was associated with greater adherence to healthier dietary patterns in children aged 4 to 7 years (19) and 2 to 8 years-old (20).
Breastfeeding duration was also associated with a better diet quality among 1 to 5 years-old children (21). An introduction of complementary feeding after 4 months of age, compared with children who started before 4 months, was associated with a dietary pattern characterized by high variety of fruits and vegetables at age 2 years-old (22). However, in 1 to 5-years old children no significant association was found between timing of initiation of complementary feeding and child’s diet (21).
Although some previous studies have examined the association of early feeding practices with children’s weight status and, at a less extent, with their dietary patterns, no previous studies have explored the relationship of such feeding practices with dietary patterns explaining a specific outcome of interest, such as children’s BMI. This study aims to explore the association of early-life feeding practices (breastfeeding duration; timing of exclusive and non-exclusive breastfeeding; age and type of complementary feeding) with dietary patterns identified at 7 years-old that explain BMI z-scores later in life (at age 10).
Methods
Study design and participants
This study included participants from the Generation XXI, a population-based birth cohort, previously described elsewhere (23, 24). A total of 8647 children and 8495 mothers were recruited between April 2005 and August 2006 at all public maternities of the metropolitan area of Porto, Portugal. All the families were invited to follow-up when children were aged 4, 7 and 10 years of age (86%, 80% and 76% of participation rates, respectively).
The present study included data from baseline and 4, 7 and 10 years-old follow- ups. Data from 3673 children were included in the current analysis, after excluding twins (n= 222) and children with missing information on variables of interest (n= 1402).
Comparison of baseline characteristics between the current study sample and the
remaining cohort at baseline (n=4974) showed that participating mothers were slightly older (mean= 29.9 years-old; Standard Deviation (SD) = 5.13 vs mean= 28.4; SD= 6.32) and more educated (mean= 11.3 years; SD= 4.29 vs mean= 9.8; SD= 4.13) comparing to mothers in the remaining cohort. The Cohen’s effect size of 0.25 and 0.34, respectively, suggests that the magnitude of the differences was not high and is mostly due to the large sample size (25).
All the study phases complied with the Ethical Principles for Medical Research Involving Human Subjects expressed in the Declaration of Helsinki. Generation XXI was approved by the University of Porto Medical School/S. João Hospital Centre ethics committee, and by the Portuguese Data Protection Authority. A signed informed consent was required for all participants and signed by their legal representatives, in accordance with Helsinki, about the benefits and potential discomforts, together with information on all examinations and procedures to be performed during the evaluation, at baseline and in the subsequent follow-up evaluations.
Data collection
Data on maternal and children’s characteristics were collected in face-to-face interviews using structured questionnaires performed by trained researchers and also through clinical records, self-reported questionnaires or physical examinations, at baseline, 4, 7 and 10 years-old.
Early feeding practices
At the 4-years-old follow-up, any breastfeeding was asked about to the main caregiver, usually mothers, and the variable was converted into a dichotomous question (no vs. yes). Duration of breastfeeding was also asked in relation to exclusive (only breast milk was provided to the child) and non-exclusive breastfeeding (i.e.
breastfeeding in combination with other types of milk and/or foods); answers were categorized into “Never to <3 month; ≥3 to <5 months; ≥5 to <6 months; and ≥6 months”
At the 7-years-old follow-up, the timing of introduction to complementary feeding was assessed and three categories were created “<4 months; ≥4 to ≤5 months;
after a few years, in a sensitivity analysis in children with data at both 15 months of age (recent complementary feeding) and 7 years-old, answers were compared and a moderate-to-high agreement was found. The first food introduced at the complementary feeding was also reported by the main caregiver, which was categorized into “Soup; Cereals porridge; Fruit; Others”.
Dietary Patterns’ definition
At the 7-years-old follow-up, a validated food frequency questionnaire (FFQ) covering the previous 6 months was applied to the main caregiver in order to assess the habitual dietary intake at this age. The FFQ was composed by 38 food items/groups and 9 response options which varied from “never” to “more than 4 times a day”. It was previously validated in Generation XXI, by comparing data with 3-day food records and biomarkers (26).
In a previous work from our research group, two dietary patterns were identified at 7 years-old using partial least squares (27), a hybrid method which simultaneously explains the maximum variance of the predictor variables (foods) and the response variable (usually nutrients or biomarkers as an intermediate step to explain a certain outcome) (28). In this study, the 38 food items/groups from the FFQ were considered the predictor variables and the response variable was the BMI z-score at 10 years-old. In result, two dietary patterns were derived explaining 10.1% of the food groups variance at 7 years-old and 4.23% of the BMI z-score variance at age 10.
As previously described, the first pattern (“Energy-dense foods“ dietary pattern - PLS- factor 1) was characterized by processed meats, energy-dense foods and soft drinks and low consumption of vegetable soup, and it was significantly associated with BMI z- score at age 10 (β=0.193; 95%CI: 0.166;0.221). It showed greater discriminatory capacity for identifying obese vs. non-obese children at 10 years of age (area under the curve (AUC) of 0.63, 95%CI: 0.61;0.65). It explained 4.14% of variance of food groups at age 7 and 3.74% of variance of BMI z-score at age 10. On the other hand, the second derived pattern (“Fish-based“ dietary pattern - PLS-factor 2) was characterized by higher fish intake and lower in energy-dense foods, and explained 5.92% of variance of food groups (higher than the “Energy-dense foods” dietary pattern), but it only managed to explain 0.49% of the BMI z-score variance at age 10.
Covariates
At baseline, the following variables of interest were collected through structured questionnaires: maternal age and education (number of completed years of age and schooling, at delivery), body mass index (BMI) before pregnancy (self-reported and categorized into under/normal weight and overweight/obese, according to the World Health Organization (WHO) criteria) and child’s sex.
At the 7-years-old follow-up, physical activity was evaluated based on a dichotomous question “Does the child practice any kind of scheduled and regular sports at school or out of school?”. The child’s anthropometrics were obtained by trained personnel during physical examinations at 7 and 10 years-old, according to standard procedures. Body weight and height were evaluated through a digital scale (TANITA®, Arlington Heights, IL, USA) (to the nearest 0.1 kg) and a wall stadiometer (SECA®, Hamburg, Germany) (to the nearest 0.1 cm), respectively. Children’s BMI was calculated (kg/m2) and classified according to the age- and sex-specific WHO BMI SD scores (BMI z-scores) and the children were classified into obese (BMI >2SD) and non- obese (29, 30).
Statistical Analysis
Descriptive statistics of the children and their mother’s characteristics were computed at baseline, 4, 7 and 10 years of age. Continuous variables are described as means and SD, and categorical variables are shown as total counts and their corresponding percentages.
Generalized linear models were run to test the associations with calculation of regression coefficients (β̂) and the corresponding 95% confidence intervals (95% CI).
Two models are presented: an unadjusted model (model 0 or crude model), and a model adjusted for maternal age, education, regular physical activity at 7 years-old and maternal BMI before pregnancy (model 1). Further adjustment for children’s birth weight was also tested, but the magnitude of the associations did not change (results not shown).
An interaction of the child’s sex in the associations was studied, and because significant differences were found, all analyses were stratified by child’s sex.
The significance level was set at 5% and SPSS Statistics v. 25.0 (SPSS®, Inc., 2017) was used to perform all the statistical analyses.
Results
Table 1 presents the children and their mothers’ characteristics (n=3673), stratified by sex (50.6% were boys). Mothers, at baseline, had a mean age of 30 years- old, 11 years of education, and a mean BMI of 24 kg/m2, within the normal weight range. Children were born with a mean birth weight of 3208 g, and this was higher in boys, and at 10 years-old 26.4% were overweight/obese (27.5% in boys and 25.2% in girls). Approximately 86% of children had a regular physical activity at 7 years-old.
Almost all children were breastfed (94%), but 38.1% were exclusively breastfed for less than 3 months, similar by sex. Most children started the introduction of complementary feeding between 4 to 5 months of age (65.6%). The first food introduced was cereal porridge in 58.8 % of boys and 57.0% of girls, and vegetable soup in 35.8% of children.
As mentioned elsewhere, two dietary patterns were identified at 7 years-old that explain BMI z-scores of children at age 10. In Table 2 (for the “Energy-dense foods” dietary pattern) and in Table 3 (for the “Fish-based” dietary pattern) are described the associations with the early feeding practices, stratified by child’s sex. In boys and girls, no significant associations were found between breastfeeding characteristics (both exclusive and non-exclusive) and the “Energy-dense foods”
dietary pattern. In girls, those who started the complementary feeding between ≥4 to
<5 months and ≥6 months of age presented lower scores in the obesity-related dietary pattern, compared to those starting before 4 months of age. However, after adjustment for the potential confounders, this association was no longer significant (Table 2, adjusted model). Boys and girls who started the complementary feeding with cereals porridge, compared with those who started with soup, had lower scores in the
“Energy-dense foods” dietary pattern (Boys: β̂=-0.183; 95%CI:-0.292;-0.074; Girls: β̂=- 0.155; 95%CI:-0.259;-0.050) (Table 2). Girls who started complementary feeding with
