Leena Räsänen

Cohort Profile: The Cardiovascular Risk in Young Finns Study

In Finland, coronary heart disease (CHD) incidence was very high in the 1960s and 1970s. In line with this high incidence, the Seven Countries Study showed that the level of serum cholesterol in Finns was also the highest among the investigated countries in the 1960s. Because several studies indicated that the atherosclerotic process starts early in life, and in accord with the World Health Organization Recommendation of 1978 which stated that studies assessing atherosclerosis precursors in children should be initiated, a program was launched in Finland in the late 1970s to study cardiovascular risk in the youth. The Cardiovascular Risk in Young Finns Study was designed as a collaborative effort between five university departments of medical schools (i.e. in Helsinki, Kuopio, Oulu, Tampere and Turku) and several other institutions in Finland. The aim was to study the levels of CHD risk factors and their determinants in children and adolescents of various ages in different parts of the country. Two pilot studies were carried out in 1978 (N1⁄4 264, age 8 years) and in 1979 (N1⁄4 634, aged 3, 12 and 17 years). The first main cross-sectional (baseline) study was performed in 1980. The baseline study included 3596 children and adolescents aged 3, 6, 9, 12, 15 and 18 years. Between 1980 and 1992, these cohorts were followed up at 3-year intervals. The latest examination of the Cardiovascular Risk in Young Finns Study was performed in 2001, when the participants were young adults, aged 24–39 years. At the time of writing, the 27-year (i.e. 27 years since the start of the study when the participants are aged 30–45 years) follow-up field studies are being conducted, and will be completed in the beginning of 2008.

Dietary factors determining diabetes and impaired glucose tolerance. A 20-year follow-up of the Finnish and Dutch cohorts of the seven countries study.

OBJECTIVE To investigate the role of diet as a predictor of glucose intolerance and non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS At the 30-year follow-up survey of the Dutch and Finnish cohorts of the Seven Countries Study, in 1989/1990, men were examined according to a standardized protocol including a 2-h oral glucose tolerance test. Information on habitual food consumption was obtained using the cross-check dietary history method. Those 338 men in whom information on habitual diet was also available 20 years earlier were included in this study. Subjects known as having diabetes in 1989/1990 were excluded from the analyses. RESULTS Adjusting for age and cohort, the intake of total, saturated, and monounsaturated fatty acids and dietary cholesterol 20 years before diagnosis was higher in men with newly diagnosed diabetes in the survey than in men with normal or impaired glucose tolerance. After adjustment for cohort, age, past body mass index, and past energy intake, the past intake of total fat was positively associated with 2-h postload glucose level (P < 0.05). An independent inverse association with the past intake of vitamin C was observed (P < 0.05). These associations were independent of changes in the intake of fat and vitamin C during the 20-year follow-up. An increase in the consumption of vegetables and legumes, potatoes, and fish during the 20-year follow-up was inversely related with 2-h glucose level (P < 0.05). CONCLUSIONS Although the regression coefficients were in general not very large, these results indicate that a high intake of fat, especially that of saturated fatty acids, contributes to the risk of glucose intolerance and NIDDM. Foods such as fish, potatoes, vegetables, and legumes may have a protective effect. In addition, the observed inverse association between vitamin C and glucose intolerance suggests that antioxidants may also play a role in the development of derangements in glucose metabolism.

Longitudinal changes in diet from childhood into adulthood with respect to risk of cardiovascular diseases: The Cardiovascular Risk in Young Finns Study

Objective: To assess nutrient intakes relevant in the prevention of cardiovascular diseases (CVD) among young adults in Finland and to find past and present determinants of quality of diet.Design: Prospective study, 21 years of follow-up.Setting: The Cardiovascular Risk in Young Finns Study, Finland.Subjects: At baseline in 1980: 3569 children aged 3–18 y participated (83% of those invited), and every second of them (1780) were selected to the dietary study. At follow-ups in 1986 and 2001: 1200 and 1037 of the original sample, respectively, participated.Methods: Food consumption was assessed using 48-h dietary recall. Intakes in 2001 were compared with those obtained in 1980 and 1986. Nutrients selected for further examination were those implicated in the risk of CVD: saturated, monounsaturated, polyunsaturated and n-3 fatty acids, fibre and salt. An index describing the quality of adulthood diet was constructed. Multivariate logistic regression was used to identify independent childhood and adulthood determinants of the quality index.Results: The average intakes showed substantial changes since 1980. Intakes of fat and saturated fat had decreased, while the consumption of vegetables and fruit had increased. However, a great disparity was present between the recommended levels and actual intakes for many of the nutrients, particularly salt, saturated fat and fibre. Intake of fat and consumption of vegetables in childhood and physical activity in adulthood were important health behavioural determinants of the cardiovascular quality of the adult diet. Socio-demographic factors, including education of the subject and their parents, had no significant associations with diet.Conclusions: While intakes of energy and nutrients have changed favourably in Finnish young adults between 1980 and 2001 with regard to the risk of CVD, they are still far from recommended levels. Childhood diet is a significant determinant of adult diet even after 21 y.Sponsorship: This study was supported by the Academy of Finland (grant 77841) and Juho Vainio Foundation.

Toxic cyanobacteria (blue-green algae) in Finnish fresh and coastal waters

A survey of the occurrence of toxic blooms of cyanobacteria in Finnish fresh and coastal waters was made during 1985 and 1986. Toxicity of the freeze-dried water bloom samples was tested by mouse-bioassay (i.p.). Forty-four per cent (83/188) of the bloom samples were found to be lethally toxic. Hepatotoxic blooms (54) were almost twice as common as neurotoxic ones (29). Anabaena was the most frequently found genus in toxic and non-toxic blooms and it was present in all neurotoxic samples. Statistical associations were found between hepatotoxicity and incidence of Microcystis aeruginosa, M. viridis, M. wesenbergii, Anabaena flos-aquae and Anabaena spiroides. Neurotoxicity was statistically associated with Anabaena lemmermannii, Anabaena flos-aquae and Gomphosphaeria naegeliana. Isolation of strains of cyanobacteria confirmed the occurrence of hepatotoxic and neurotoxic strains of Anabaena, as well as hepatotoxic strains of Microcystis and Oscillatoria species.Toxic blooms caused cattle poisonings at three different lakes during the study period. Toxic blooms also occurred in drinking water sources. Our study shows that toxic cyanobacteria are more common in Finnish lakes than would be expected on the basis of animal poisonings. The results of this study show the existence of toxic cyanobacteria in Finnish water supplies and the need for their continued study as agents of water based disease.

Atherosclerosis precursors in Finnish children and adolescents. I. General description of the cross-sectional study of 1980, and an account of the children's and families' state of health.

ABSTRACT. The paper describes the general outline of a multicentre study on the risk factors of coronary heart disease (CHD) and their determinants in children of various ages in different parts of Finland. The study was a cross‐sectional one, and was carried out in 1980 in five university cities of Finland with medical schools and in 12 rural communities in their vicinity. The randomized sample included an equal number of boys and girls, aged 3, 6, 9, 12, 15, and 18 years, and an equal number of urban and rural population in each area. The total sample size was 4,320 subjects, and of these 3,596 participated (83.1 %). The families received before the medical examination of the child, questionnaires on the Socioeconomic background, the childs general health and development, the parents’and grandparents’health status, and the childs food and exercise habits. At the physical examination also a fasting blood sample (lipids, insulin, trace elements) was taken, a bundle of hair was cut for trace element analysis, and a 48‐hour recall on food intake was obtained from every second subject.

Epidemiology of childhood diabetes mellitus in Finland-background of a nationwide study of type 1 (insulin-dependent) diabetes mellitus

SummaryA nationwide study of childhood Type 1 (insulin-dependent) diabetes mellitus was established in 1986 in Finland, the country with the highest incidence of this disease worldwide. The aim of the project called “Childhood Diabetes in Finland” is to evaluate the role of genetic, environmental and immunological factors and particularly the interaction between genetic and environmental factors in the development of Type 1 diabetes. From September 1986 to April 1989, 801 families with a newly-diagnosed child aged 14 years or younger at the time of diagnosis were invited to participate in this study. The vast majority of the families agreed to participate in the comprehensive investigations of the study. HLA genotypes and haplotypes were determined in 757 families (95%). Our study also incorporates a prospective family study among non-diabetic siblings aged 3–19 years, and two case-control studies among the youngonset cases of Type 1 diabetes. During 1987–1989, the overall incidence of Type 1 diabetes was about 35.2 per 100,000 per year. It was higher in boys (38.4) than in girls (32.2). There was no clear geographic variation in incidence among the 12 provinces of Finland. Of the 1,014 cases during these 3 years only six cases were diagnosed before their first birthday. The incidence was high already in the age group 1–4-years old: 33.2 in boys and 29.5 in girls. Of the 801 families 90 (11.2%) were multiple case families, of which 66 had a parent with Type 1 diabetes at the time of diagnosis of the proband. The prevalence of Type 1 diabetes in the parents of these newly-diagnosed diabetic children was higher in fathers (5.7%) than in mothers (2.6%).

Infant Feeding in Finnish Children <7 yr of Age With Newly Diagnosed IDDM

Objective We studied associations between the type of feeding in infancy and the incidence of insulin-dependent diabetes mellitus (IDDM). Research Design And Methods We studied 103 newly diagnosed diabetic children <7 yr of age and 103 age- and sex-matched population-based control children in a countrywide study. Results The risk of IDDM was decreased (P < 0.05) among children breast-fed for at least 7 mo (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.24–0.85) or exclusively breast-fed for at least 3 (OR 0.33, 95% CI 0.13–0.84) or 4 (OR 0.43, 95% CI 0.22–0.84) mo. Also, children who were ≥4 mo old at the time of introduction of supplementary milk feeding had a lower risk of diabetes (OR 0.48, 95% CI 0.26–0.91). Conclusions The protective effects of a long duration of breast-feeding and a late introduction of dairy products on the risk of IDDM remained significant after adjusting for the mothers education.

Diet, serum fatty acids, and atopic diseases in childhood

Background: The reasons behind the reported increase in the occurrence of childhood atopic sensitization rates are unclear. We wanted to evaluate the association between dietary fats, serum fatty acids, and the occurrence and development of atopic diseases.

Life-time risk factors and progression of carotid atherosclerosis in young adults: the Cardiovascular Risk in Young Finns study

AIMS The aim of this study is to evaluate whether childhood risk factors are associated with a 6-year change in carotid intima-media thickness (IMT) in young adulthood independent of the current risk factors. METHODS AND RESULTS The Cardiovascular Risk in Young Finns cohort consisted of 1809 subjects who were followed-up for 27 years since baseline (1980, age 3-18 years) and having carotid IMT measured both in 2001 and 2007. Cardiovascular risk factors were assessed repeatedly since childhood. A genotype risk score was calculated using 17 newly identified genetic variants associating with cardiovascular morbidity. The number of childhood risk factors (high LDL-cholesterol, low HDL-cholesterol, high blood pressure, obesity, diabetes, smoking, low physical activity, infrequent fruit consumption) was associated with a 6-year change in adulthood IMT. In subjects with 0, 1, 2, and > or =3 childhood risk factors, IMT [mean (95% CI)) increased by 35 (28-42), 46 (40-52), 49 (41-57), and 61 (49-73) microm (P = 0.0001). This association remained significant when adjusted for adulthood risk score and genotype score (P = 0.007). Of the individual childhood variables, infrequent fruit consumption ((beta (95% CI) for 1-SD change -5(-9 to -1), P = 0.03) and low physical activity (-6(-10 to -2), P = 0.01) were associated with accelerated IMT progression after taking into account these variables assessed in adulthood. CONCLUSION These findings indicate that children with risk factors have increased atherosclerosis progression rate in adulthood, and support the idea that the prevention of atherosclerosis by means of life style could be effective when initiated in childhood.

Early Introduction of Dairy Products Associated with Increased Risk of IDDM in Finnish Children

Associations between infant-feeding patterns and risk of IDDM were investigated in a nationwide Finnish case-control study of 690 IDDM children <15 yr of age. Each child was matched by date of birth and sex to a randomly selected population-based control child. Univariate analysis revealed that the risk of IDDM was increased by ∼1.5 in children for whom breast-feeding was terminated at <2 mo of age, doubled in those who were exclusively breast-fed for <2 mo, and doubled in those who were introduced to dairy products at <2 mo of age. In further multivariate analyses of these factors, it was found that introduction of dairy products at an early age was the most important risk factor, and the observed univariate effects of duration of breast-feeding variables were explained by their correlation with this factor. This is the first observational study to show that early introduction of dairy products is independently associated with an increased risk of IDDM. Adjustment for mothers education and age, childs birth order, or birth weight did not affect the results.