Composition and cross-sectional area of muscle fibre types in relation to daily gain and lean and fat content of carcass in Landrace and Yorkshire pigs

Selostus: Lihassolutyypin ja lihassolun poikkipinta-alan yhteys sian kasvuun ja ruhon koostumukseen maatiaisessa ja yorkshiressa

Genetic, prenatal and postnatal determinants of weight gain and obesity in young children – The STEPS Study

Genetic, Prenatal and Postnatal Determinants of Weight Gain and Obesity in Young Children – The STEPS Study University of Turku, Faculty of Medicine, Department of Paediatrics, University of Turku Doctoral Program of Clinical Investigation (CLIPD), Turku Institute for Child and Youth Research. Conditions of being overweight and obese in childhood are common health problems with longlasting effects into adulthood. Currently 22% of Finnish boys and 12% of Finnish girls are overweight and 4% of Finnish boys and 2% of Finnish girls are obese. The foundation for later health is formed early, even before birth, and the importance of prenatal growth on later health outcomes is widely acknowledged. When the mother is overweight, had high gestational weight gain and disturbances in glucose metabolism during pregnancy, an increased risk of obesity in children is present. On the other hand, breastfeeding and later introduction of complementary foods are associated with a decreased obesity risk. In addition to these, many genetic and environmental factors have an effect on obesity risk, but the clustering of these factors is not extensively studied. The main objective of this thesis was to provide comprehensive information on prenatal and early postnatal factors associated with weight gain and obesity in infancy up to two years of age. The study was part of the STEPS Study (Steps to Healthy Development), which is a follow-up study consisting of 1797 families. This thesis focused on children up to 24 months of age. Altogether 26% of boys and 17% of girls were overweight and 5% of boys and 4% of girls were obese at 24 months of age according to New Finnish Growth references for Children BMI-for-age criteria. Compared to children who remained normal weight, the children who became overweight or obese showed different growth trajectories already at 13 months of age. The mother being overweight had an impact on children’s birth weight and early growth from birth to 24 months of age. The mean duration of breastfeeding was almost 2 months shorter in overweight women in comparison to normal weight women. A longer duration of breastfeeding was protective against excessive weight gain, high BMI, high body weight and high weight-for-length SDS during the first 24 months of life. Breast milk fatty acid composition differed between overweight and normal weight mothers, and overweight women had more saturated fatty acids and less n-3 fatty acids in breast milk. Overweight women also introduced complementary foods to their infants earlier than normal weight mothers. Genetic risk score calculated from 83 obesogenic- and adiposity-related single nucleotide polymorphisms (SNPs) showed that infants with a high genetic risk for being overweight and obese were heavier at 13 months and 24 months of age than infants with a low genetic risk, thus possibly predisposing to later obesity in obesogenic environment. Obesity Risk Score showed that children with highest number of risk factors had almost 6-fold risk of being overweight and obese at 24 months compared to children with lowest number of risk factors. The accuracy of the Obesity Risk Score in predicting overweight and obesity at 24 months was 82%. This study showed that many of the obesogenic risk factors tend to cluster within children and families and that children who later became overweight or obese show different growth trajectories already at a young age. These results highlight the importance of early detection of children with higher obesity risk as well as the importance of prevention measures focused on parents. Keywords: Breastfeeding, Child, Complementary Feeding, Genes, Glucose metabolism, Growth, Infant Nutrition Physiology, Nutrition, Obesity, Overweight, Programming

Diet and Probiotics during Pregnancy - Endorsing developmental Programming

Maternal obesity has been shown to increase the risk for adverse reproductive health outcomes such as gestational diabetes, hypertension, and preeclampsia. Moreover, several studies have indicated that overnutrition and maternal obesity adversely program the development of offspring by predisposing them to obesity and other chronic diseases later in life. The exact molecular mechanisms leading to developmental programming are not known, but it has recently been suggested that obesity-related low-grade inflammation, gut microbiota and epigenetic gene regulation (in particularly DNA methylation) participate in the developmental programming phenomenon. The aim of this thesis was to evaluate the effect of diet, dietary counseling and probiotic intervention during pregnancy in endorsing favorable developmental programming. The study population consisted of 256 mother-child pairs participating in a prospective, double-blinded dietary counselling and probiotic intervention (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12) NAMI (Nutrition, Allergy, Mucosal immunology and Intestinal microbiota) study. Further overweight women were recruited from maternal welfare clinics in the area of Southwest Finland and from the prenatal outpatient clinic at Turku University Hospital. Dietary counseling was aimed to modify women’s dietary intake to comply with the recommended intake for pregnant women. Specifically, counseling aimed to affect the type of fat consumed and to increase the amount of fiber in the women’s diets. Leptin concentration was used as a marker for obesity-related low-grade inflammation, antioxidant vitamin status as an efficiency marker for dietary counselling and epigenetic DNA methylation of obesity related genes as a marker for probiotics influence. Results revealed that dietary intake may modify obesity-associated low-grade inflammation as measured by serum leptin concentration. Specifically, dietary fiber intake may lower leptin concentration in women, whereas the intakes of saturated fatty acids and sucrose have an opposite effect. Neither dietary counselling nor probiotic intervention modified leptin concentration in women, but probiotics tended to increase children’s leptin concentration. Dietary counseling was an efficient tool for improving antioxidant vitamin intake in women, which was reflected in the breast milk vitamin concentration. Probiotic intervention affected DNA methylation of dozens of obesity and weight gain related genes both in women and their children. Altogether these results indicate that dietary components, dietary counseling and probiotic supplementation during pregnancy may modify the intrauterine environment towards favorable developmental programming.