Fat and fat-free mass of healthy Swedish children show tracking during early life, but there are differences.

AIM: Obesity may start early in life. We investigated relationships between size and body composition variables in infancy and at 4 years of age using valid estimates of body composition. The results were compared to those obtained when body mass index (BMI) was used to estimate body fatness at 4 years. METHODS: Using air displacement plethysmography, size, fat mass and fat-free mass were studied, between 2007 and 2015, in 253 full-term healthy Swedish children at 1 week, 12 weeks and 4 years of age. RESULTS: Positive associations between variables in infancy and at 4 years were found at 1 and 12 weeks for weight, height, BMI, fat-free mass and fat-free mass index (p ≤ 0.002) and for fat mass, per cent body fat and fat mass index (p ≤ 0.04) at 12 weeks. Fat mass gained during infancy correlated positively (p ≤ 0.031) with per cent fat mass, fat mass index and BMI, all at 4 years. In girls, gains in fat-free mass during infancy correlated with BMI (p = 0.0005) at 4 years. CONCLUSION: The results provide information regarding body composition trajectories during early life and demonstrate limitations of BMI as a proxy for body fatness when relating early weight gain to variables, relevant for later obesity risk.

Associations between sun exposure and other lifestyle variables in Swedish women.

PURPOSE: Sun exposure is associated with risk of several chronic diseases including cancer. The study aim is to investigate whether sun behaviors are related to other lifestyle risk factors of cancer. METHODS: We analyzed data collected in 2003-2004 by self-completed questionnaire from 34,402 Swedish women aged 40-61 years, who comprised 70% of a cohort of originally recruited from a population registry in 1991-1992 (n = 49,259). Participants were asked about annual number of sunburns and annual number of weeks of swimming and sunbathing during 1991-2002, solarium use during 1991-1998 and current sunscreen use. RESULTS: Compared to non-drinkers, the prevalence ratio (95% CI) in women who drank >10 g of alcohol per day was 1.64 (1.49, 1.81) for having >1 sunburn per year, 1.39 (1.29, 1.51) for swimming and sunbathing >2.5 weeks per year and 1.55 (1.41, 1.70) for using a solarium >1 time per 2 months, adjusting for demographic and lifestyle variables. Tobacco smokers were less likely to report sunburn and to use sunscreen, and more likely to sunbath and use solaria, compared with non-smokers. Physical activity was associated positively with swimming and sunbathing, and with the separate use of solaria and sunscreens, but not with number of sunburns. The lifestyle variables that explained most of the variation in sun behavior were alcohol and smoking. CONCLUSIONS: Our results suggest that alcohol consumption and tobacco smoking are potential lifestyle confounders which should be adjusted in studies investigating the association that sun and/or solarium exposure may have with risk of several cancer sites.

Physical activity intensity, sedentary behavior, body composition and physical fitness in 4-year-old children: results from the ministop trial.

BACKGROUND: Existing knowledge on associations of physical activity (PA) and sedentary behavior (SB) with body composition and physical fitness in preschoolers is limited. OBJECTIVE: To examine associations of PA and SB with body composition and physical fitness in healthy Swedish 4-year-old children. METHODS: We utilized baseline data collected in 2014 for the population-based MINISTOP trial (n=307). Light-intensity PA (LPA), moderate-intensity PA (MPA), vigorous-intensity PA (VPA), moderate-to-vigorous PA (MVPA) and SB were measured using accelerometry (ActiGraph-wGT3x-BT). Body composition was measured using air-displacement plethysmography, and physical fitness (that is, cardiorespiratory fitness, lower and upper body muscular strength and motor fitness) was measured using the PREFIT fitness test battery. Multiple linear regression models adjusted for relevant confounders, and in addition, isotemporal substitution models were applied. RESULTS: Greater MVPA was associated with lower fat mass percent (%FM, P=0.015), and greater VPA and MVPA were associated with higher fat-free mass index (FFMI, P=0.002 and P=0.011). In addition, greater VPA and MVPA were associated with higher scores for all physical fitness tests (P=0.042 to P<0.001). The results for MVPA were primarily due to VPA. SB was associated with weaker handgrip strength (P=0.031) when PA was not adjusted, but after adjusting also for VPA, the significant association disappeared (P=0.25). Substituting 5 min per day of SB, LPA or MPA with 5 min per day of VPA was associated with higher FFMI and better scores for cardiorespiratory fitness and motor fitness. Correspondingly, substituting 5 min per day of VPA with SB or LPA was associated with weaker performance for lower muscular strength. CONCLUSIONS: Time spent on VPA was associated with higher FFMI and better physical fitness. The results suggest that promoting VPA may be important to improve childhood body composition and physical fitness already at an early age.

No association between adherence to the healthy Nordic food index and cardiovascular disease amongst Swedish women: a cohort study.

BACKGROUND: In several intervention trials, a healthy Nordic diet showed beneficial effects on markers of cardiovascular disease. We investigated the association between a healthy Nordic diet and clinical diagnosis of cardiovascular disease. OBJECTIVE: Our aim was first to examine the association between a healthy Nordic food index (wholegrain bread, oatmeal, apples/pears, root vegetables, cabbages and fish) and the incidence of overall cardiovascular disease (ischaemic heart disease, stroke, arrhythmia, thrombosis and hypertensive disease), and secondly to test for possible effect modification by smoking, body mass index (BMI), alcohol consumption and age. METHODS: We conducted an analysis of data from the prospective Swedish Women's Lifestyle and Health cohort, including 43 310 women who completed a food frequency questionnaire in 1991-1992, and followed up until 31 December 2012 through Swedish registries. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. RESULTS: During follow-up, 8383 women developed cardiovascular disease. We found no association between the healthy Nordic food index and overall cardiovascular disease risk or any of the subgroups investigated. There was a statistically significant interaction with smoking status (P = 0.02), with a beneficial effect only amongst former smokers (HR 0.96, 95% CI 0.94-0.99 per 1-point increment). CONCLUSION: The present results do not support an association between a healthy Nordic food index and risk of cardiovascular disease in Swedish women. There was also no effect modification by alcohol intake, BMI or age. Our finding of an interaction with smoking status requires reproduction.

Cross-sectional examination of 24-hour movement behaviours among 3- and 4-year-old children in urban and rural settings in low-income, middle-income and high-income countries: the SUNRISE study protocol.

INTRODUCTION: 24-hour movement behaviours (physical activity, sedentary behaviour and sleep) during the early years are associated with health and developmental outcomes, prompting the WHO to develop Global guidelines for physical activity, sedentary behaviour and sleep for children under 5 years of age. Prevalence data on 24-hour movement behaviours is lacking, particularly in low-income and middle-income countries (LMICs). This paper describes the development of the SUNRISE International Study of Movement Behaviours in the Early Years protocol, designed to address this gap. METHODS AND ANALYSIS: SUNRISE is the first international cross-sectional study that aims to determine the proportion of 3- and 4-year-old children who meet the WHO Global guidelines. The study will assess if proportions differ by gender, urban/rural location and/or socioeconomic status. Executive function, motor skills and adiposity will be assessed and potential correlates of 24-hour movement behaviours examined. Pilot research from 24 countries (14 LMICs) informed the study design and protocol. Data are collected locally by research staff from partnering institutions who are trained throughout the research process. Piloting of all measures to determine protocol acceptability and feasibility was interrupted by COVID-19 but is nearing completion. At the time of publication 41 countries are participating in the SUNRISE study. ETHICS AND DISSEMINATION: The SUNRISE protocol has received ethics approved from the University of Wollongong, Australia, and in each country by the applicable ethics committees. Approval is also sought from any relevant government departments or organisations. The results will inform global efforts to prevent childhood obesity and ensure young children reach their health and developmental potential. Findings on the correlates of movement behaviours can guide future interventions to improve the movement behaviours in culturally specific ways. Study findings will be disseminated via publications, conference presentations and may contribute to the development of local guidelines and public health interventions.

Longitudinal study of the maternal insulin-like growth factor system before, during and after pregnancy in relation to fetal and infant weight.

BACKGROUND: The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete. AIMS: To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight. METHODS: Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression. RESULTS: One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = -0.43 to -0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003). CONCLUSION: We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.

Media framing and construction of childhood obesity: a content analysis of Swedish newspapers.

Objective: Despite lower prevalence than most European countries, childhood obesity is a Swedish public health priority due to its lasting health impacts and socioeconomic patterning. Mass media content influences public and political perceptions of health issues, and media framing of childhood obesity may influence perceptions of its solutions. This study examines framing of childhood obesity in Swedish morning and evening newspapers from 1996 to 2014. Methods: Content analysis of 726 articles about childhood obesity published in the five most-circulated Swedish newspapers. Article content coded quantitatively and subjected to statistical analysis, describing relationships between themes and trends over time. Results: Childhood obesity was consistently problematised, primarily in health terms, and linked to socio-economic and geographical factors. The yearly frequency of articles peaked in 2004, followed by a decline, corresponding with evidence about prevalence. Childhood obesity was framed as being driven by individual behaviours more frequently than structural or environmental factors. Structural framings increased over time, but constructions of the problem as driven by individual behaviours, particularly parenting, remained prominent. Conclusions: A relative growth in structural framings of causes and solutions over time, combined with prominent coverage of socio-economic inequalities, might be indicative of public and political amenability towards societal-level solutions, but individual behaviours remain prominent in framing of the issue. Health advocates might incorporate these insights into media engagement.

The effect of thermal stress on protein composition in dogwhelks (Nucella lapillus) under normoxic and hyperoxic conditions.

In this laboratory study, dogwhelks (Nucella lapillus) were collected from the intertidal zone and exposed to 16 degrees C (ambient), 26.5 degrees C and 30 degrees C under normal and hyperoxic conditions respectively. It was shown that there was no thermally induced mortality at 26.5 degrees C, but that the mortality rate was 40-50% in 30 degrees C. This mortality rate was reduced to 10% if extra oxygen was provided, indicating that oxygen supply was setting the limit for whole organism thermal tolerance. Tissue samples were then analysed for protein features using two-dimensional gel electrophoresis, and both up and down regulation of proteins were visualised by silver staining and crosswise comparisons of gels from control vs. treated animals. The results clearly show that the protein profiles from dogwhelks exposed to increased water temperatures differ from those of the control, but that increased oxygen availability alleviates these differences thus increasing the similarity between heat-shocked and control animal protein pattern. This implies a more stable protein metabolism and might explain the increased survival of heat-shocked individuals when extra oxygen is supplied.

Longitudinal assessment of body composition in healthy Swedish children from 1 week until 4 years of age.

BACKGROUND/OBJECTIVES: Knowledge of longitudinal body composition development is required to identify the mechanisms behind childhood overweight and obesity and to prevent these conditions. However, accurate data on this development in early childhood are lacking. Our aim was to describe the longitudinal body composition development in healthy young Swedish children. SUBJECTS/METHODS: Body size and composition were assessed in 26 children using air-displacement plethysmography (1 and 12 weeks and 4.4 years of age) and isotope dilution (1.5 and 3 years of age) and compared with available reference data. RESULTS: Body fat (%) for boys (n=16) was 12.8±3.9 (1 week), 25.6±4.8 (12 weeks), 28.2±3.8 (1.5 years), 27.3±5.1 (3 years) and 26.1±3.5 (4.4 years). For girls (n=10) these values were 15.3±2.9, 25.7±3.9, 27.9±3.3, 26.3±7.2 and 26.0±5.3, respectively. These values were above the Fomon reference values at 1.5 years of age and later and higher than the Butte reference (P<0.05) for boys at 1.5 years of age. At all ages the coefficients of variation were higher for body fat (%) (12-30%) than for BMI (4-11%). CONCLUSIONS: At 4 years of age our children had more body fat than indicated by reference data. This high level may have already been established at 1.5 years of age but our small sample and the lack of appropriate reference data limit the possibility of drawing firm conclusions. Our results demonstrate the limitations of BMI when investigating overweight and obesity in early life and highlight the need for appropriate reference body composition data in infants and young children.European Journal of Clinical Nutrition advance online publication, 23 August 2017; doi:10.1038/ejcn.2017.125.

Evaluation of the wrist-worn ActiGraph wGT3x-BT for estimating activity energy expenditure in preschool children.

BACKGROUND/OBJECTIVES: Easy-to-use and accurate methods to assess free-living activity energy expenditure (AEE) in preschool children are required. The aims of this study in healthy preschool children were to (a) evaluate the ability of the wrist-worn ActiGraph wGT3x-BT to predict free-living AEE and (b) assess wear compliance using a 7-day, 24-h protocol. SUBJECTS/METHODS: Participants were 40 Swedish children (5.5±0.2 years) in the Mobile-based intervention intended to stop obesity in preschoolers (MINISTOP) obesity prevention trial. Total energy expenditure (TEE) was assessed using the doubly labeled water method during 14 days. AEE was calculated as (TEEx0.9) minus predicted basal metabolic rate. The ActiGraph accelerometer was worn on the wrist for 7 days and outputs used were mean of the daily and awake filtered vector magnitude (mean VM total and mean VM waking). RESULTS: The ActiGraph was worn for 7 (n=34, 85%), 6 (n=4, 10%), 5 (n=1, 2.5%) and 4 (n=1, 2.5%) days (a valid day was ⩾600 awake minutes). Alone, mean VM total and mean VM waking were able to explain 14% (P=0.009) and 24% (P=0.001) of the variation in AEE, respectively. By incorporating fat and fat-free mass in the models 58% (mean VM total) and 62% (mean VM waking) in the variation of AEE was explained (P<0.001). CONCLUSIONS: The wrist-worn ActiGraph wGT3x-BT in combination with body composition variables explained up to the 62% of the variation in AEE. Given the high wear compliance, the wrist-worn ActiGraph has the potential to provide useful information in studies where physical activity in preschool children is measured.

Parental body mass index and its association with body composition, physical fitness and lifestyle factors in their 4-year-old children: results from the MINISTOP trial.

BACKGROUND/OBJECTIVES: To examine the association between parental body mass index (BMI) and their offspring's body composition, physical fitness and lifestyle factors (that is, sedentary time, physical activity and diet). SUBJECTS/METHODS: A total of 307 preschoolers (4.5±0.1 years) and their parents (fathers: 38.1±5.1 years and mothers: 35.6±4.2 years) participated in this study. Parental BMI was calculated using self-reported weight and height. Preschoolers body composition was assessed using: BMI, fat mass percentage, fat mass index, fat-free mass index (measured via air-displacement plethysmography) and waist circumference. Physical fitness was assessed by the PREFIT fitness battery. Lifestyle factors were assessed using the ActiGraph wGT3x-BT (sedentary time and physical activity), and the mobile-phone based tool for energy balance in children (diet). RESULTS: Parental BMI were positively associated with their offspring's BMI (paternal BMI: standardised beta, ß=0.233, P<0.001; maternal BMI: ß=0.186, P=0.001), fat mass index (paternal BMI: ß=0.130, P=0.026; maternal BMI: ß=0.163, P=0.005), fat-free mass index (paternal BMI: ß=0.214, P<0.001; maternal BMI: ß=0.119, P=0.036) and waist circumference (paternal BMI: ß=0.178, P=0.001; maternal BMI: ß=0.179, P=0.001). A negative association was found between maternal BMI and their offspring's standing long jump test (ß=-0.132, P=0.022). Paternal BMI was associated with their offspring's sedentary time (ß=0.100, P=0.026), whereas parental BMI was not associated with neither physical activity nor diet (all P⩾0.104). CONCLUSIONS: Parental BMI was positively associated with their offspring's BMI, fat as well as fat-free mass index and waist circumference. Moreover, a higher paternal and maternal BMI were related to higher levels of sedentary time and a lower performance in the standing long jump test of their offspring, respectively.

Health-related physical fitness is associated with total and central body fat in preschool children aged 3 to 5 years.

OBJECTIVES: To investigate whether health-related physical fitness is associated with total and central body fat in preschool children. METHODS: A total of 403 Spanish children aged 3-5 years (57.8% boys) participated in the study. Health-related physical fitness was measured by the PREFIT battery: the handgrip strength and the standing long-jump tests (muscular strength), the 4 × 10 m shuttle run (speed-agility), the one-leg stance tests (balance) and the PREFIT-20 m shuttle run test (cardiorespiratory fitness). Body mass index and waist circumference were used as markers of total and central body fat, respectively. RESULTS: There were significant associations between all health-related physical fitness tests and body mass index (ß = 0.280 ± 0.054, ß = -0.020 ± 0.006, ß = 0.154 ± 0.065 and ß = -0.034 ± 0.011 for the handgrip strength, standing long jump, 4 × 10 m shuttle run and PREFIT-20 m shuttle run tests, respectively, all P ≤ 0.019) after adjusting for sex and age. Similarly, there was significant associations of standing long jump (ß = -0.072 ± 0.014), 4 × 10 m shuttle run (ß = 0.652 ± 0.150) and PREFIT-20 m shuttle run tests (ß = -0.102 ± 0.025) with waist circumference (all P ≤ 0.001), except for handgrip strength (ß = 0.254 ± 0.145, P = 0.081) and one-leg stance (ß = -0.012 ± 0.009, P = 0.156). CONCLUSIONS: The present study extends previous findings in older youth. Fitness assessment should be introduced in future epidemiological and intervention studies in preschool children because it seems to be an important factor determining health.

Prevalence of overweight/obesity and fitness level in preschool children from the north compared with the south of Europe: an exploration with two countries.

BACKGROUND: North-south differences in the prevalence of obesity and fitness levels have been found in European adolescents, yet it is unknown if such differences already exist in very young children. OBJECTIVES: This study aims to compare the prevalence of overweight/obesity and fitness levels in preschool children aged 4 years from Sweden (north of Europe) and Spain (south of Europe). METHODS: The sample consisted of 315 Swedish and 128 Spanish preschoolers. Anthropometry (weight, height, waist circumference) and fitness (strength, speed-agility, balance and cardiorespiratory fitness) were assessed. Analysis of covariance adjusted for age, sex and height/body mass index (BMI) was used. RESULTS: Preschool children from Sweden had lower prevalence of overweight/obesity than their peers from Spain (World Obesity Federation, mean difference, MD = -9%, P = 0.010; World Health Organization, MD = -11%, P = 0.011). Concerning fitness, preschoolers from Spain were more fit in terms of upper-muscular strength (MD = +0.4 kg, P = 0.010), speed-agility (MD = -1.9 s, P = 0.001), balance (MD = +4.0 s, P = 0.001) and cardiorespiratory fitness (MD = boys = +6.6 laps, girls = +2.3 laps; P < 0.001 for all), yet they had worse lower-muscular strength (MD = -7.1, P ≤ 0.001) than those from Sweden. Differences in upper-muscular strength were largely explained by differences in BMI, and differences in cardiorespiratory fitness should be interpreted cautiously due to some methodological deviations. CONCLUSIONS: These findings suggest that a higher prevalence of overweight/obesity in Spain compared with Sweden is present already at early childhood, while differences in physical fitness components showed mixed findings.

Gestational weight gain according to Institute of Medicine recommendations in relation to infant size and body composition.

BACKGROUND: Intrauterine life may be a critical period for programming childhood obesity; however, there is insufficient knowledge concerning how gestational weight gain (GWG) affects infant fat mass (FM) and fat-free mass (FFM). OBJECTIVES: The aim of this study was to investigate relationships between GWG according to Institute of Medicine (IOM) recommendations and infant size, FM and FFM. We also investigated if the associations were different for normal-weight and overweight/obese women. METHODS: This study included 312 healthy Swedish mother-infant pairs. Infant body composition at 1 week of age was assessed using air-displacement plethysmography. Maternal GWG was defined as below, within or above the 2009 IOM recommendations. Multiple regression analyses were used. RESULTS: Compared with women whose weight gain was within IOM recommendations, women with weight gain below the recommendations had infants that were shorter (-0.7 cm, P = 0.008) when adjusting for confounders. Normal-weight women exceeding IOM recommendations had infants with higher FM (+58 g, P = 0.008) compared with normal-weight women who gained within the recommendations. No corresponding association was observed for overweight/obese women. CONCLUSIONS: Inadequate GWG was associated with shorter infants, while excessive GWG was associated with greater infant FM for women who were of normal weight before pregnancy.

Assessment of handgrip strength in preschool children aged 3 to 5 years.

We investigated whether there is an optimal grip span for determining the maximum handgrip strength in preschool children and if it is influenced by gender, age, or hand size. A total of 292 preschool children (3-5 years; 59.2% boys) carried out the handgrip strength test with different grip spans (4.0, 4.5, 5.0, 5.5, and 6.0 cm). The hand size was also measured. We also determined the reliability of the optimal grip span in another group of children (n = 56, 57% boys) who did the test twice, with a 3-hour difference between tests. The results showed that 4.0 cm is the optimal grip span to determine the maximum handgrip strength in preschool children. This result applied to both genders, all age groups, and hand sizes. Paired t-tests showed no significant differences between test and retest. These findings may guide clinicians and researchers in selecting the optimal grip span when measuring handgrip strength in preschool children.Level IV.

Variation in the fat mass and obesity-related (FTO) genotype is not associated with body fatness in infants, but possibly with their length.

BACKGROUND: Data relating variation at the fat mass and obesity-related (FTO) locus (rs9939609) to fat mass in infancy are inconclusive. OBJECTIVE: To study relationships between FTO genotype and infant size (at 1 and 12 weeks and at 1 year of age) and body composition (at 1 and 12 weeks). METHODS: Body composition was assessed using air displacement plethysmography in 207 infants. FTO was genotyped using the TaqMan assay. RESULTS: The number of risk alleles was related to length at 1 and 12 weeks (P = 0.007-0.033) but not to fat mass. The relationship to length was stronger in boys than in girls. CONCLUSIONS: Our results suggest that the FTO genotype is not related during infancy to fat mass but is related to length in boys but not in girls.

Physical activity pattern and activity energy expenditure in healthy pregnant and non-pregnant Swedish women.

BACKGROUND/OBJECTIVES: Energy costs of pregnancy approximate 320 MJ in well-nourished women, but whether or not these costs may be partly covered by modifications in activity behavior is incompletely known. In healthy Swedish women: (1) to evaluate the potential of the Intelligent Device for Energy Expenditure and Physical Activity (IDEEA) to assess energy expenditure during free-living conditions, (2) to assess activity pattern, walking pace and energy metabolism in pregnant women and non-pregnant controls, and (3) to assess the effect on energy expenditure caused by changes in physical activity induced by pregnancy. SUBJECTS/METHODS: Activity pattern was assessed using the IDEEA in 18 women in gestational week 32 and in 21 non-pregnant women. Activity energy expenditure (AEE) was assessed using IDEEA, as well as using the doubly labelled water method and indirect calorimetry. RESULTS: AEE using the IDEEA was correlated with reference estimates in both groups (r=0.4-0.5; P<0.05). Reference AEE was 0.9 MJ/24 h lower in pregnant than in non-pregnant women. Pregnant women spent 92 min/24 h more on sitting, lying, reclining and sleeping (P=0.020), 73 min/24 h less on standing (P=0.037) and 21 min/24 h less on walking and using stairs (P=0.049), and walked at a slower pace (1.1 ± 0.1 m/s versus 1.2±0.1 m/s; P=0.014) than did non-pregnant controls. The selection of less demanding activities and slower walking pace decreased energy costs by 720 kJ/24 h and 80 kJ/24 h, respectively. CONCLUSION: Healthy moderately active Swedish women compensated for the increased energy costs of pregnancy by 0.9 MJ/24 h. The compensation was mainly achieved by selecting less demanding activities.

Birth weight in relation to endometrial and breast cancer risks in Swedish women.

An examination of birth weight in a Swedish cohort study of 38,566 women showed no significant association between birth weight and endometrial cancer, but supported a protective role for low birth weight for premenopausal breast cancer.

Dietary fat and breast cancer risk in the Swedish women's lifestyle and health cohort.

We investigated whether dietary intakes of total fat, monounsaturated fat (MUFA), polyunsaturated fat (PUFA) and saturated fat (SFA) were associated with breast cancer risk in a prospective cohort of 49 261 Swedish women (30-49 years at enrolment), which yielded 974 breast cancer cases by December 2005. Further, we evaluated if associations differed by oestrogen and/or progesterone receptor tumour status. Total fat, MUFA, PUFA or SFA were not associated with risk overall. However, women in the highest MUFA and PUFA quintile intake had a reduced breast cancer risk after age 50 years (hazard ratios: 95% confidence interval=0.45: 0.25-0.99 and 0.54: 0.35-0.85, respectively) compared to women in the lowest quintile. The associations did not differ by oestrogen or progesterone receptor status. Despite the negative findings, type of fat during premenopausal years may have later differential effects on risk.