Biomedical subjects
Publications and source records attributed to J Viikari.
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Plant sterol supplementation reduces serum cholesterol concentration but may increase serum plant sterol concentrations, especially in children. We determined whether natural dietary plant sterols derived mainly from vegetable oil or margarine in early childhood affect serum concentrations of plant sterols (campesterol and sitosterol) and cholesterol precursor sterols (Delta-8 cholestenol, desmosterol, and lathosterol), reflecting endogenous cholesterol synthesis. We measured the serum sterol concentrations using gas liquid chromatography in 20 healthy 13-mo-old intervention children in a randomized, prospective study designed to decrease exposure of the children to known environmental atherosclerosis risk factors and in 20 control children. The diet of the intervention children was rich in plant sterols due to replacement of milk fat with vegetable fat, whereas the diet of the control children contained only small amounts of plant sterols. The intervention children consumed twice as much plant sterols as the control children (P < 0.001). Their serum concentrations of campesterol and sitosterol were 75% and 44% higher, respectively, than those in the control children (P < 0.001 for both), but serum cholesterol precursor sterol concentrations did not differ between the two groups. We conclude that doubling dietary plant sterol intake almost doubles serum plant sterol concentrations in 13-mo-old children, but has no effect on endogenous cholesterol synthesis. Relative intestinal absorption of natural plant sterols from the diet in early childhood is similar to that in adults.
High serum cholesterol concentration is one of the key risk factors in development of atherosclerosis, which may begin early in life and later progress to symptomatic coronary heart disease. In adults, apoE polymorphism strongly influences cholesterol metabolism, as subjects with apoE 3/4 or 4/4 (collectively called apoE4) phenotype absorb cholesterol effectively and thus also have higher cholesterol absorption-reflecting plant sterol concentrations in serum than subjects with other apoE phenotypes. Because of the inverse correlation of absorption and synthesis of cholesterol, concentrations of cholesterol synthesis-reflecting serum cholesterol precursor sterols are lower in subjects with apoE4 than in subjects with other phenotypes. To analyze whether apoE phenotype affects cholesterol absorption and synthesis in early childhood, we measured serum plant sterol (campesterol and sitosterol) and cholesterol precursor sterol (desmosterol and lathosterol) concentrations in healthy 13-month old children using gas-liquid chromatography. The 36 study children were participants in a randomized prospective trial (the Special Turku Coronary Risk Factor Intervention Project) aimed at decreasing exposure of the children to environmental atherosclerosis risk factors. The 16 apoE4 children had 30% to 50% higher cholesterol-adjusted campesterol and sitosterol concentrations in serum than the 20 apoE 3/3 children (p = 0.002 and p = 0.02, respectively). The concentrations of cholesterol precursor sterols in serum did not differ between the two groups of children. We conclude that the young apoE4 children may absorb cholesterol and plant sterols more effectively than the children with apoE 3/3 phenotype without compensatory reduction in endogenous synthesis of cholesterol.
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BACKGROUND: We showed previously that repeated dietary counseling during the first 3 years of life reduces the concentration of serum nonfasting cholesterol. We have now extended the study to children 5 years of age and analyzed fasting blood samples, enabling LDL cholesterol calculations for the first time. METHODS AND RESULTS: Families of 7-month-old infants (n=1062) were randomized to a control group (n=522) or an intervention group (n=540) that received individualized dietary counseling with the aims of a fat intake of 30% to 35% of daily energy, a saturated/monounsaturated/polyunsaturated fatty acid ratio of 1:1:1, and a cholesterol intake of <200 mg/d. Nutrient intakes were studied biannually, nonfasting serum lipid values were studied annually, and fasting values were studied at 5 years of age. The intervention children always had lower intakes of saturated fat and cholesterol than the control children. The intervention boys had 0.39 mmol/L (P:<0.0001) lower mean serum cholesterol values than the control boys between 13 and 60 months of age, but among girls, the difference was of marginal significance (0.15 mmol/L, P:=0.052). Five-year-old intervention boys had 9% lower mean serum LDL cholesterol concentrations than the control boys (P:=0.0002; 95% CI, -0.39 to -0.12 mmol/L), whereas no difference was observed in girls. In both sexes, serum triglyceride concentrations were similar in the 2 groups. CONCLUSIONS: The restriction of saturated fat and cholesterol intake by repeated, individualized dietary counseling since infancy resulted in lower serum total and LDL cholesterol concentrations at 5 years of age. However, the effect was significant only in boys.
The aim of this cross-sectional study was to investigate whether two types of physical exercise affect the growing skeleton differently. We used calcaneal quantitative ultrasound measurements (QUS) and dual-energy X-ray absorptiometry (DXA) for measurement of bone mineral density (BMD), and to test how QUS values reflect the axial DXA values in these various study groups. A total of 184 peripubertal Caucasian girls aged 11-17 years (65 gymnasts, 63 runners, and 56 nonathletic controls) were studied. Weight, height, stage of puberty, years of training, and the amount of leisure-time physical activity were recorded. Broadband ultrasound attenuation (BUA) and sound of speed (SOS) through the calcaneus were measured. The BMD of the femoral neck and the lumbar spine were measured by DXA. The differences in mean values of bone measurements among each exercise group were more evident in pubertal than prepubertal girls. The mean BUA and SOS values of the pubertal gymnasts were 13.7% (77.8 dB/MHz versus 68.4 dB/MHz, P < 0.05) and 2.2% (1607.7 m/s versus 1572.4 m/s, P < 0.001) higher than of the controls, respectively. The mean BMD of the femoral neck in the pubertal gymnasts and runners was 20% (0.989 g/cm2 versus 0.824 g/cm2, P < 0.001) and 9.0% (0.901 g/cm2 versus 0.824 g/cm2, P < 0.05) higher than in the controls, respectively. The amount of physical activity correlated weakly but statistically significantly with all measured BMD and ultrasonographic values in the pubertal group (r = 0.19-0.35). The correlation between ultrasonographic parameters and BMD were weak, but significant among pubertal runners (r = 0.47-0.55) and controls (r = 0.39-0.42), whereas the DXA values of the femoral neck and the ultrasonographic parameters of the calcaneus did not correlate among highly physically active gymnasts. By stepwise regression analysis, physical activity accounted for much more of the variation in the DXA values than the ultrasonographic values. We conclude that the beneficial influence of exercise on bone status as measured by ultrasound and DXA was evident in these peripubertal girls. In highly active gymnasts the increase of the calcaneal ultrasonographic values did not reflect statistically significantly the BMD values of the femoral neck.
We investigated the effect of physical activity and sports participation on LDL oxidation in vivo and on lipid risk factors in 183 teenage girls (9-15 years): 64 gymnasts, 61 runners, and 58 controls. Oxidized LDL was measured as baseline levels of conjugated dienes in LDL lipids (ox-LDL). The gymnasts had a 15% lower ratio of LDL conjugated dienes to LDL cholesterol (ox-LDL:LDL ratio, P = 0.0052) compared to controls, and the difference persisted when the body mass index was included as a covariate (ANCOVA, P = 0.013). Also, the gymnasts had a 12% higher ratio of HDL cholesterol to total cholesterol than the controls (ANCOVA, P = 0.046). There were no differences in the other common lipid risk factors between the groups. The ox-LDL:LDL ratio correlated negatively with HDL cholesterol (r = -0.23, P=0.0021) and with physical activity METs (multiples of resting metabolic rate) (r = -0.21, P=0.0040). Our study strengthens the evidence that the atherogenic risk is influenced favourably by physical exercise and sporting activities as early as in adolescents. This risk reduction is associated with lower mildly oxidized LDL in adolescent girls.
As genetically determined apolipoprotein E (apo E) phenotypes influence serum cholesterol concentration, we analysed whether serum triglyceride values are also affected by the apo E phenotypes in infants. Non-fasting serum triglyceride values were measured in 7- and 13-month-old participants in the STRIP project, a randomised, prospective trial aimed at reducing children's exposure to known atherosclerosis risk factors (n=1062). The mean+/-S.D. non-fasting serum triglyceride concentrations in 7-month-old infants with apo E4/4 (n=36), E3/4 (n=209), E3/3 (n=412), and E2/3 (n=66) were 2. 05+/-1.24, 1.81+/-0.90, 1.63+/-0.90, and 1.71+/-0.83 mmol/l, respectively. Triglyceride concentrations were higher in infants with apo E4/4 or 3/4 than in those with apo E3/3 (P-value for difference 0.01 and 0.009, respectively). The apo E phenotype similarly influenced non-fasting serum triglyceride concentrations at the age of 13 months. The differences in serum triglyceride values in apo E4(+) infants (apo E3/4 and 4/4 infants combined) and apo E4(-) infants (apo E2/3 and 3/3 infants combined) occurred independently of the relative weight of the infant, milk type used at 7 months of age (breast milk or formula), and time elapsed from the previous meal. To conclude, apo E phenotypes regulate non-fasting serum triglyceride values in healthy infants. Apo E3/4 and apo E4/4 predispose infants to higher values than apo E3/3 phenotype, suggesting that the varepsilon4 allele may increase atherosclerosis risk also via it's effect on postprandial triglyceride metabolism.
OBJECTIVE: To investigate cholesterol-lowering efficacy and safety of plant stanol ester margarine in healthy 6-year-old children already consuming a low-saturated-fat, low-cholesterol diet. STUDY DESIGN: Eighty-one intervention children from the STRIP project, a randomized prospective trial aimed at reducing exposure of young children to the known environmental atherosclerosis risk factors, were recruited to this double-blind crossover study at 6 years of age. In randomized order the families were advised to replace daily 20 g of the child's dietary fat intake with plant stanol ester margarine or control margarine for 3 months. The washout period lasted 6 weeks. Statistical analysis was performed according to intention-to-treat principle with analysis of variance for crossover design. RESULTS: The mean daily plant stanol ester margarine consumption was 18.2 g (1.5 g plant stanol). The well-tolerated plant stanol ester margarine reduced serum total and low-density lipoprotein cholesterol concentrations by 5.4% and 7.5%, respectively (P =.0001 for both). The serum high-density lipoprotein cholesterol and triglyceride concentrations and alpha-tocopherol to low-density lipoprotein cholesterol ratio remained unchanged. The serum beta-carotene to low-density lipoprotein cholesterol ratio decreased by 19% (P =.003). CONCLUSION: Plant stanol ester margarine significantly diminishes serum total and low-density lipoprotein cholesterol concentration without adverse clinical effects in healthy children who already consume a low-saturated-fat, low-cholesterol diet but decreases the serum beta-carotene to low-density lipoprotein cholesterol ratio.
OBJECTIVE: We evaluated whether replacing a proportion of saturated fat with vegetable oils in the diet of young children increases trans fatty acid intake. STUDY DESIGN: Dietary counseling aimed to reach a dietary fat ratio of unsaturated to saturated fat of 2:1 within a total fat intake of 30% to 35% of energy (E%). Four-day food records of 813 3-year-old children were analyzed, and serum phospholipid fatty acid compositions of 25 randomly selected intervention children and 17 control children were analyzed. RESULTS: trans fatty acid intake of the intervention and control children was small (0.8 E% and 0.6 E%, respectively; P <.001). The relative content of serum phospholipid trans 18:1 was closely similar in intervention and control children (1.0% and 0.9% of all fatty acids, respectively). Trans fatty acid intake and serum trans 18:1 correlated poorly with children's serum cholesterol and HDL cholesterol concentrations and inversely with serum phospholipid arachidonic to linoleic acid ratio (r = -0.373). CONCLUSIONS: Trans fatty acid intake of children in Finland is minimal. Dietary intervention replacing saturated with unsaturated fatty acids is safe because it does not increase trans fatty acid intake or the relative content of trans fatty acids in the serum phospholipid fraction.
The association of the amount and type of physical activity with bone mineral acquisition was studied in 191 peripubertal Caucasian girls aged 9-16 years (66 gymnasts, 65 runners, and 60 nonathletic controls). Weight, height, stage of puberty, the amount of leisure-time physical activity, and years of training were recorded, and dietary calcium and vitamin D were assessed by a semi-quantitative questionnaire. The bone area, the bone mineral density (BMD), and the bone mineral content (BMC) of the femoral neck, lumbar spine and antebrachium were measured by dual-energy x-ray absorptiometry. The unadjusted mean values of BMD at the femoral neck were 15.2% higher in the pubertal gymnasts than in the controls (P<0.001). Compared with the controls, the mean BMC adjusted for bone area of the pubertal gymnasts at the femoral neck and lumbar spine was 16.4% and 10.8% higher, respectively. When comparing the association of the type of physical activity among the pubertal athletics by multiple regression analysis, height, physical activity, gymnastics, and Tanner stage emerged as significant variables and accounted for 54.7% and 63.4% of the total variation in BMD of the femoral neck and lumbar spine, respectively. These results indicate that physical activity is associated with bone mineral acquisition in peripubertal girls and that high-impact weight-bearing exercise seems to be particularly associated with the increase of the BMD at the femoral neck.
Interferon-alpha (IFN-alpha) is used in the treatment of many haematological diseases and it is known that IFN-alpha may affect bone turnover. The effect of IFN-alpha on bone metabolism was studied in 10 haematological patients. The mean duration of the treatment was 4 (range: 2.8-7.2) months. Besides the usual markers of bone metabolism, levels of the cross-linked C-terminal telopeptide of type I collagen (ICTP), the N-terminal propeptide of type I procollagen (PINP) and the bone-specific alkaline phosphatase were measured. The bone mineral density was measured by computed tomography. During IFN-alpha treatment, serum ICTP decreased from a mean of 5.4 (range: 1.8-12.4) to 3.6 (range: 1.4-8.8) microg/l (P = 0.017). All other variables reflecting bone metabolism remained unaltered during IFN-alpha treatment. The bone mineral density remained unchanged. It was concluded that the observed decrease in ICTP may be an indicator of a beneficial therapeutic effect of IFN-alpha on bone turnover, resulting in decreased bone resorption. However, it is possible that elevated pretreatment ICTP values reflected disease of the bone marrow.
STRIP (the Special Turku coronary Risk factor Intervention Project) is an ongoing intervention trial which aims at a permanent reduction in the intake of saturated fat and cholesterol starting in childhood. A total of 75 intervention and 63 control children was studied consecutively at the ages of 7 and 13 mo, and 2, 3 and 5 y to evaluate the influence of such intervention on serum cholesterol ester (CE) fatty acid composition, a widely used biomarker of fatty acid intake. Analysis of 4-d food records showed that total intake of fat and of saturated fat increased with age in both groups of children but was constantly lower in intervention than in control children, e.g. at the age of 5 y the mean intakes of total fat and of saturated fatty acids were 31.1 E% and 33.9 E% and 12.1 E% and 14.6 E% in intervention and control children, respectively (p = 0.009 and 0.0001, respectively). Serum CE fatty acid compositions did not differ between the 2 groups at any age; the mean proportion of CE linoleic acid was 52.4% and 52.0% in 5-y-old intervention and control children, respectively. Correlation analysis showed, however, that the percentage of linoleic acid and of polyunsaturated fatty acids in CE reflected well the respective dietary intakes (r = 0.36; p = 0.0001 for both coefficients). In conclusion, CE fatty acid composition did not differ between the intervention and control groups, whereas CE linoleic and total polyunsaturated fatty acids reflected well the differences in their intakes at the individual level.
The aim of this study is to examine sodium intake and dietary sodium sources of 1-5-y-old children in a prospective, randomized long-term coronary heart disease prevention trial, focused on dietary fat modification. Counselling included no advice about reducing salt in the children's diets. Food consumption of 100 intervention children and 100 control children was recorded for 3 consecutive days at the age of 13 mo and for 4 consecutive days at the ages of 3 and 5 y. Sodium intakes were calculated using the Micro Nutrica program. Children's mean daily sodium (NaCl) consumption (intervention and control children combined) was 1600+/-527 mg (4.0+/-1.3 g), 1900+/-504 mg (4.8+/-1.3 g) and 2200+/-531 mg (5.5+/-1.3 g) at the ages of 13 mo and 3 and 5 y, respectively. The intervention children consumed as much or slightly more sodium than the control children at all ages studied. Half the sodium consumption was derived from added salt in commercially prepared or homemade foods. Milk, meat products, bread and cereals were other important sodium sources. In conclusion, nutrition counselling in the Special Turku Coronary Risk Factor Intervention Project (STRIP) trial, with its main focus on the quality of fat in child nutrition, has had minimal influence on children's sodium intake. To avoid excessive sodium intake in children, dietary counselling should include information about salt use, and food manufacturers should be encouraged to provide more low-sodium products.