Research topics
Find out more about our research topics – obesity measures, microbiota, dental caries, genetics, food consumption and eating behaviour, physical activity and screen time, mental health and autoimmune diseases.
The main aim of Fin-HIT is to explore risk and protective factors for excess weight / weight gain. We use anthropometric measures such as height, weight and waist circumference and derive indices of them to infer on weight status and growth. Body mass index (BMI; kg/m2) is a widely used measure to determine weight status in children and adolescents, but it does not differentiate between fat or muscle mass or where the excess mass is located. In addition, BMI depends on age and sex, and it is often referred to as BMI-for-age or BMI z-score.
There are two international reference values to classify underweight, normal weight, overweight and obesity in children: the International Obesity Task Force (IOTF) and the WHO growth reference. The prevalence of overweight is slightly overestimated by the WHO growth reference 2007 compared with the IOTF. IOTF incorporates survey data from Brazil, Great Britain, Hong Kong, Singapore, United States, and The Netherlands and is currently utilized in our cohort.
Waist-to-height ratio, calculated by dividing the waist circumference (WC) by height, has recently gained attention as a measure for central obesity in children. It is considered a more reliable predictor of cardiovascular disease risk in children and adolescents than BMI.
A commonly used measure in Finland is weight-for-height. New Finnish references for weight-for-height and BMI z-score were constructed in 2011.
The microbes living in or on humans (the human microbiome) keep us healthy by digesting food, strengthening the immune system and helping to prevent pathogens from invading tissues and organs. The microbiota plays a major role in both health and disease. Most of the microbiota studies have focused on gut, but less is known about the oral and saliva microbiota; their determinants and possible associations with various health outcomes are yet to be explored.
In humans, different salivary bacteria were found between vegans and omnivores (plant- and animal-based diet). We are aiming to identify saliva bacteria that is linked to the development of obesity, oral diseases, autoimmune diseases, and signs of metabolic syndrome. In addition, we are exploring different determinants of saliva microbiota diversity and composition (e.g. diet, antimicrobial drugs, oral health, host genetics). Recently, we found a significant difference in microbial diversity and composition in saliva and differently abundant bacteria in children with high sugar consumption; or children living with central obesity. We are also studying the changes in microbiota in our cohort’s participants in a 3 year follow up (first wave vs second wave). We are moving on from traditional 16S rRNA sequencing towards modern techniques such as deep/shallow shotgun metagenomics sequencing, which provide an insight on the functional and mechanistic aspect of the microbiota’s role in the human body.
Dental caries, also known as tooth decay, is a major health problem worldwide, likely associated with obesity. It is common among both adults and children, but especially children and adolescents are at risk. Besides oral hygiene, frequent consumption of dietary sugars is the leading cause of caries; bacteria in the oral cavity break down dietary sugars and produce acids that destroy tooth enamel, slowly leading to tooth decay. The saliva microbiota may play a critical role in maintaining oral health, and changes in it may lead to various diseases including caries. The microbial presence and activity in saliva could be an indicator of oral health status, and caries can be understood as a shift of the oral microbiota from the commensal to pathogenic bacteria. We are interested to map out the associations between caries, obesity and sugar consumption, and moreover, to study the saliva microbiota profiles in children with and without caries. The purpose is to expand our understanding of the microbial etiology of caries in children, and hopefully provide novel therapeutic strategies for the prevention of caries.
Obesity is a complex trait that is affected by multiple common genetic variants, which are likely to interact with lifestyle factors, modifying our susceptibility to weight gain. To date, 2.1 million common genetic variants together explain 23% of the variation in BMI (Khera eta l. 2019). One of such variants is fat mass- and obesity-associated gene (FTO). More interestingly, the impact of genetic susceptibility on BMI may vary during the life course.
There are situations in which obesity results from the mutation or defect in a single gene (monogenetic obesity). These are rare, early-onset, extreme conditions that may present with additional clinical features including endocrine and mental disorders.
Epigenetic alterations are suspected to contribute to the development of obesity. Epigenetic processes involve altering gene activity without altering the DNA sequence, resulting in phenotypic changes, such as obesity. DNA methylation, the most well studied epigenetic mark, is affected by various lifestyle factors. The epigenetic change process occurs gradually with ageing, smoking, antibiotics, air pollution, and others.
Currently, we are interested to identify important genetic and epigenetic factors, and to evaluate how these factors are associated with weight gain and obesity in adolescents.
A healthy diet and eating behaviour established during childhood are crucial for promoting wellbeing and preventing noncommunicable diseases. Food consumption can be measured with various methods and on several levels. We have used a food propensity questionnaire that indicates how many times a week children and adolescents eat or drink certain food items. In the third data collection, when the participants had reached adulthood, we used a comprehensive food frequency questionnaire to gather more detailed information on their dietary patterns, as well as their energy and nutrient intake.
We are interested in associations of different eating behaviours with weight status, weight gain, and other health outcomes in adolescents and young adults. We focus particularly on the tendency towards overeating. Our aim is to identify parental and child characteristics associated with overeating, and examine how overeating predicts weight development during adolescence. Moreover, we investigate the similarities and differences in food consumption between children with overeating and binge eating, as well as identify which factors most strongly predict weight gain. Our findings can be targeted to manage overeating and prevent overweight.
Physical activity can be defined as any bodily movement produced by the contraction of skeletal muscles that increases energy expenditure above a basal level. Exercise, in the other hand, refers to physical activity that is planned, structured, repetitive and performed with the goal of improving health or fitness. In short, all exercise is physical activity, but not all physical activity is exercise.
Sedentary behaviour (from the Latin sedere, ‘to sit’) refers to any waking behaviour that does not increase energy expenditure substantially above the resting level while sitting, reclining or lying (e.g. sitting in an automobile). Further, sedentary screen time refers to the time spent using a screen-based devise (e.g. smartphone, tablet, computer, television) while being sedentary (= sitting, reclining or lying).
In the Fin-HIT, we have assessed both the children’s and their guardians’ physical activity and screen time with a questionnaire when the children were around 9-12 years old and again at a follow-up when they were 13-15 years old. The purpose is to examine whether and how physical activity and screen time are related to weight, weight gain and other aspects of the children’s health.
The rising prevalence of mental health issues, alongside obesity, presents a significant public health challenge. Nearly half of mental disorders emerge during childhood and adolescence, a turbulent period, marked by significant changes. Depression and anxiety disorders are the most common, yet subclinical symptoms are much more widespread. Early mental health issues can have long-lasting effects, not only on emotional well-being but also behaviors that contribute to obesity, such as poor eating and sleeping habits and lower physical activity.
Conversely, obesity can also contribute to mental health challenges through stigma, low self-esteem, and social isolation. Mental health and obesity are related in complex ways, often influencing each other in a reinforcing cycle. However, the exact nature of their relationships remains not fully understood.
In Fin-HIT-study, mental health is assessed using validated questionnaires for a subsample at age 11 and in the entire cohort at age of 20. Self-esteem has been measured across all waves for the entire cohort. Our research focuses on exploring how different weight trajectories during adolescence are linked to mental health outcomes in emerging adulthood. We aim to identify the factors influencing these relationships to provide valuable insights for developing targeted interventions. These interventions seek to address both physical and emotional well-being, ultimately enhancing quality of life and reducing the long-term burden of chronic diseases.
Autoimmune diseases are chronic diseases caused by an abnormal immune response toward a person’s own healthy tissues. For unknown reasons, the prevalence of many autoimmune diseases in children such as type 1 diabetes mellitus, autoimmune thyroiditis, juvenile idiopathic arthritis and inflammatory bowel disease has been increasing in the past decades. Our hypothesis is that these diseases might have mutual risk factors. Thus, it is important to recognize the risk factors in order to prevent further increases in the prevalence.
Our aim in the Fin-HIT study is to search for potential environmental factors that might trigger autoimmune diseases. We search these risk factors among maternal and perinatal factors, dietary patterns, body composition, exposure to antibiotics (pre- and perinatally) and change of oral microbiota. Our findings will increase the understanding of the role of environmental factors in the development of autoimmune diseases, and could, therefore, be utilized in prevention. They may also provide tools for early detection of autoimmune diseases.
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