Karri Silventoinen University of Helsinki and Osaka University

Karri Silventoinen University of Helsinki and Osaka University

Childhood is an important phase of life and creates the base for all further life Childhood is the time of rapid physiological development Development in childhood can modify metabolism and so affect strongly the further health profile However also many health habits can be formed over childhood affecting further health

Measuring childhood nutrition is challenging FAO offers information on food consumption at country level, but it is difficult to measure how it is distributed within populations Human anthropometrical measures offer a shortcut to measure nutrition at population level Especially height and relative weight have been widely measured and used in scientific research Childhood is very important phase of life in the formation on adult anthropometrics

Trait correlations and additive genetic and specific environmental correlations of height and body mass index from 1 to 17 years of age with 18 years of age in Swedish twin boys correlation A) Height 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Age Trait correlation Additive genetic correlation Specific environmental correlation correlation 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 B) Body mass index 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Age Source: Silventoinen et al. Int J Obes 2007 and Am J Hum Biol 2008

Over the human history malnutrition has been the major problem in human populations Human growth is sensitive for malnutrition and thus both children and adult height reflects at population level inadequate nutrition in childhood At population level most part of variation of height is because of genetic differences between individuals, but also variation in environmental factor affects individual differences Comparing monozygotic and dizygotic twins offer a powerful tool to separate genetic and environmental parts of variation Association between height and standard of living can be seen when comparing populations Association between height and health gives evidence how childhood nutrition affect health status in adulthood

Estimates of variation of height explained by genetic factors, environmental factors shared by co-twins and environmental factors unique foe each twin individual US women US men Sweden women Sweden men Norway women Norway men Netherlands women Netherlands me Italy men Finland women Finland men Denmark women Denmark men Australia women Australia men 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Additive genetic factors Common environmental factors Specific environmental factors Silventoinen et al Twin Res 2003 and Am J Hum Biol 2004

185 180 175 170 165 160 155 Change in mean body height by birth cohort in Finland and Sweden 150 1920-1929 1930-1939 1940-1949 1950-1959 1960-1969 Finnish men Swedish men Finnish women Swedish women Silventoinen et al Eur J Public Health 2001

Prevalence of stunting among pre-school children 1990-2020 based on WHO references Onis et al, Publ Health Nutr 2011

Hazard ratio 0.97 Hazard ratios for CHD incidence in adulthood per 1 unit increase in z-scores of height from 7 to 13 years of age in Danish children 0.95 0.93 0.91 0.89 0.87 0.85 7 8 9 10 11 12 13 Age Boys Girls Source: Silventoinen et al. 2012 PLoS One

Cognitive test performance in Finnish and Danish elderly twins Both in Finland and Denmark shorter height was associated with poorer performance in cognitive test Indicates that chilhood nutrition has effect also on cognitive development seen still decades later

In recent decades, excess nutrition has become a major health problem globally Obesity leads to multiple severe health problems Cardiovascular diseases, type 2 diabetes, musculo-skeletal diseases, many cancers, low self-esteem, social discrimination Still a problem especially in industrialized countries following Westernized lifestyle, but an increasing problem also in many middle income societies For example in Mexico obesity is a bigger problem than in USA Many societies suffer double burden having both malnutrition and excess nutrition Low quality nutrition can easily lead to double burden even in same families Children suffer inadequate nutrition but still develop obesity in adulthood In Western countries obesity is linked to poor socio-economic position So also obesity is linked to material deprivation

Ng et al. Lancet 2014

Ng et al. Lancet 2014

Body mass index and socio-economic position in Finland and Japan University of Helsinki Toyama University

Males 26 24 22 Finland 26 24 22 Japan 20 Managers Professionals Clerical employees Manual workers 20 Statistical significance of the interaction between country and occupational position: P=0.015 Silventoinen et al. J Epi 2013

Females Finland Japan 26 26 24 24 22 22 20 Managers Professionals Clerical employees Manual workers 20 Statistical significance of the interaction between country and occupational position: P<0.0001 Silventoinen ym. J Epi 2013

Heritability of body mass index from 1 to 18 years of age: a meta analysis of nine twin studies Genetic factors Common environmental factors 0 0.4.6.7.8.9 1 Common environmental effect.05.1.15.2.25.3.35.4.45.5.55 1 5 10 15 18 Age in years 1 5 10 15 18 Age in years Silventoinen et al., Int J Obes 2009

Heritability of obesity measures as a function of physical activity: a study of Finnish and Danish twins 20 40 60 80 100 0 BMI Waist circumference Fat percent of total body mass Low Medium High Physical activity Silventoinen et al., Am J Clin Nutr 2009

Ahmad et al., PLoS Genet, 2013

Childhood nutrition has long lasting health effects Poor childhood nutrition is a risk factor for metabolic diseases but also cognitive performance in old age In Western societies, but increasingly also in middle income countries, obesity has replaced malnutrition as the major public health problem Just as for height, genetic factors have major effect on individual differences in body mass index Socio-economic differences in obesity are also a dominant feature in Western countries However environment modifies both genetic effects and socio-economic differences in obesity Twin studies offer an effective way to analyze genetic effects globally since information on twins has widely been collected

CODATwins project PI Karri Silventoinen

Thank you all the twins Osaka Twin Day 2014

Population Research Unit Department of Social Research University of Helsinki