Blood Pressure Is Lower in Children and Adolescents With a... Since Infancy: The Special Turku Coronary Risk Factor Intervention Project

Blood Pressure Is Lower in Children and Adolescents With a Low-Saturated-Fat Diet
Since Infancy: The Special Turku Coronary Risk Factor Intervention Project
Harri Niinikoski, Antti Jula, Jorma Viikari, Tapani Rönnemaa, Pekka Heino, Hanna Lagström,
Eero Jokinen and Olli Simell
Hypertension. 2009;53:918-924; originally published online April 13, 2009;
doi: 10.1161/HYPERTENSIONAHA.109.130146
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Blood Pressure Is Lower in Children and Adolescents With
a Low-Saturated-Fat Diet Since Infancy
The Special Turku Coronary Risk Factor Intervention Project
Harri Niinikoski, Antti Jula, Jorma Viikari, Tapani Rönnemaa, Pekka Heino, Hanna Lagström,
Eero Jokinen, Olli Simell
Abstract—Blood pressure was measured in the prospective randomized Special Turku Coronary Risk Factor Intervention
Project Study with an oscillometric method every year from 7 months to 15 years of age in 540 children receiving a
low-saturated-fat, low-cholesterol diet and in 522 control children. Dietary intakes, family history of parental
hypertension, and grandparental vascular disease were recorded. Systolic and diastolic blood pressures were 1.0 mm Hg
lower (95% CI for systolic: ⫺1.7 to ⫺0.2 mm Hg; 95% CI for diastolic: ⫺1.5 to ⫺0.4 mm Hg) in children receiving
low-saturated-fat counseling through childhood than in control children. Intakes of saturated fat were lower (P⬍0.001),
those of polyunsaturated fat higher (P⬍0.001), and intakes of potassium slightly higher (P⫽0.002) in the intervention
group, but sodium intakes were not influenced by the intervention (P⫽0.76). Children whose parents were hypertensive
had 4- to 6-mm Hg higher systolic and 3- to 4-mm Hg higher diastolic blood pressures than children of normotensive
parents (P⬍0.001). Diastolic blood pressure of children with grandparental vascular disease, ie, early cardiovascular or
cerebrovascular disease, tended to be higher than that of children with no grandparental disease (P⫽0.051). We
conclude that restriction of saturated fat from infancy until 15 years of age decreases childhood and adolescent blood
pressure with a meaningful population-attributable amount. The importance of childhood lifestyle counseling and
primary prevention of hypertension should be emphasized, especially in those children with a family history of
hypertension or atherosclerotic vascular disease. (Hypertension. 2009;53:918-924.)
Key Words: atherosclerosis prevention 䡲 child nutrition sciences 䡲 cholesterol 䡲 diet 䡲 hypertension
L
ong-term health risks of hypertension in children and
adolescents are substantial.1 Genes, environment, and
their interaction influence the rise of blood pressure (BP)
in childhood. The BP of children of hypertensive parents
rises more rapidly than that of children of normotensive
parents2– 4; their vascular endothelium is also less elastic5
and left ventricular mass greater6 than those of children
with no family history of hypertension. High childhood BP
predisposes to adult hypertension,7 and adult vascular
endothelial characteristics, eg, intima-media thickness of
the common carotid artery, correlate significantly with
systolic BP measured over the 2 previous decades at 12 to
18 years of age.8
Dietary sodium intake is regarded as the dietary culprit in
hypertension development, and salt restriction during the first
year of life significantly slows down the BP rise in childhood.9 However, the quantity and quality of dietary fats also
influence BP,10 –13 even without effects on weight.14 Perhaps
the most convincing of such studies is Dietary Approaches to
Stop Hypertension,14 in which 459 adults were randomly
assigned to receive one of the following: (1) a diet rich in
fruits and vegetables; (2) a “combination” diet rich in fruits,
vegetables, and high intake of low-fat dairy; or (3) a control
diet. The combination diet, ie, the diet with high intake of
fruits and vegetables and high intake of low-fat dairy,
lowered BP significantly more than the fruit-and-vegetable
diet only, and the effect was most marked in hypertensive
subjects.
These observations support the concept that genes steer the
age-dependent and environmentally modifiable increase in
BP and hypertension-induced complications, and the published data suggest that nutrition during the very first year(s)
of life may have a central role in programming of the future
BP.9 Thus, attempts to control its environmental risk factors
should be directed to the entire population,15 including
children. However, no controlled studies have been published
on the effects of a long-term, low-saturated-fat diet on BP in
childhood and adolescence.
Received February 2, 2009; first decision February 6, 2009; revision accepted March 18, 2009.
From the Departments of Paediatrics (H.N., O.S.) and Medicine (J.V., T.R.), Research Centre of Applied and Preventive Cardiovascular Medicine
(P.H., H.L.), and Turku Institute for Child and Youth Research (H.L.), University of Turku, Turku, Finland; National Public Health Institute (A.J.), Turku,
Finland; and the Department of Paediatrics (E.J.), University of Helsinki, Helsinki, Finland.
This trial has been registered at www.clinicaltrials.gov (identifier NCT00223600).
Correspondence to Harri Niinikoski, Turku University Hospital, Department of Pediatrics, Kiinamyllynkatu 4-8, 20520 Turku, Finland. E-mail
harri.niinikoski@tyks.fi
© 2009 American Heart Association, Inc.
Hypertension is available at http://hyper.ahajournals.org
DOI: 10.1161/HYPERTENSIONAHA.109.130146
918
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Niinikoski et al
In the randomized, prospective Special Turku Coronary
Risk Factor Intervention Project (STRIP) Study, children
were at 7 months randomly allocated into 2 groups: those
receiving saturated-fat– oriented counseling or a control
group.16 We recently published the 14-year follow-up of the
trial and showed that this intervention led to decreased
saturated fat intake and serum cholesterol concentrations
without effects on growth or pubertal development.17 In the
present study we reported BP values of the intervention and
control children until 15 years of age, as well as intakes of
BP-related nutrients, and studied how parental hypertension and family history of vascular disease associated with
childhood BP.
Methods
Study Design and Counseling of the Families
In the prospective, randomized STRIP Study,18 healthy infants were
randomly assigned either to receive individualized dietary and
lifestyle counseling aiming at modification of the environmental
coronary heart disease risk factors (n⫽540) or to a control group
(n⫽522) at 7 months of age. The intervention was individualized and
aimed at the child’s fat intake of 30% to 35% of daily energy (E%),
saturated:monounsaturated plus polyunsaturated fatty acid ratio of
1:2, and cholesterol intake ⬍200 mg/d (for details see Reference 16).
Breastfeeding or formula was advised during the first year of life.
After 12 months of age, 0.5 to 0.6 L of skim milk were recommended
daily. To maintain adequate fat intake, the parents were taught to add
daily 2 or 3 teaspoonfuls (10 g) of soft margarine or vegetable oil,
mainly low-erucic-acid grapeseed oil, to the child’s food from 12 to
24 months of age.
The counseling given in STRIP mainly focused on intakes of fat
and saturated fat. Consequently, intakes of salt and sodium were not
lower in the intervention than in control children during the first
years of life.19 Later, guidance toward lower sodium intakes was
started when the child reached age 8 years, but this was never the
main subject of the intervention. Ample use of vegetables, fruits,
berries, and whole grain products was encouraged.
The control children received the basic health education routinely
given at Finnish well-baby clinics and school health care. At the age
of 12 months, cow’s milk with 1.9% (1.5% after May 1995) fat was
recommended for daily use. No suggestions on the use of fats were
given to the control families, and dietary issues were discussed only
superficially.
Food Records and Anthropometric Measurements
Food consumption data were obtained using annual 4-day food
records (3-day food records before 2 years of age) as described,16 –18
and the nutrient intakes were calculated using Micro Nutrica software.20,21 The energy and energy nutrient intakes of the STRIP
children ⱕ14 years of age have been published previously.17 All of
the children were weighed and measured annually as described,17
and body mass index (BMI) was calculated as kilograms per meter
squared.
Ethics
The joint commission on ethics of the Turku University and the
Turku University Central Hospital approved the STRIP Study.
Measurement of BP
Sitting BP of intervention and control children was measured
annually from 7 months to 15 years of age using an oscillometric
noninvasive BP monitor (Criticon Dinamap 1846 SX until 2001,
thereafter Criticon Dinamap Compact T) after an appropriate rest of
ⱖ15 minutes. BP of both parents was also measured annually. The
accuracy of the device was regularly checked against a mercury
manometer. Proper cuff size according to the size of the child’s right
arm was used. Until 7 years of age, BP was measured once; at 8 to
Blood Pressure and Saturated Fat in Childhood
919
9 years of age, it was measured 2 to 4 times; and after 9 years of age
it was measured twice at each visit. BPs of the children and parents
were measured annually at times of day suitable for the family. Both
study groups were seen by the study team at the same time of year
in the same environment (similar ambient temperature, etc), and both
study groups were seen multiple times throughout the study, thereby
minimizing tension and stress in both groups.
Statistical Analyses
The energy and micronutrient and macronutrient intakes (fat, saturated fat, protein, sodium, potassium, calcium, and magnesium) of
the intervention and control children at ages 8 months to 15 years
were compared with repeated-measures ANOVA.
In BP analyses, all of the BP values of children between 7 months
and 15 years of age were used (maximum number of observations:
16). Before 8 years of age, BP was measured only once at each visit,
but the mean values of 2 to 4 BP values measured at each visit at 8
to 15 years of age were used in the statistical analyses. First,
repeated-measures ANOVA was performed to study BP of the
intervention and control children across the age points from 7 months
to 15 years. Second, BPs, weights, heights, and BMIs of intervention
and control children at the study end point (ie, at 15 years of age)
were compared by t test. Third, to evaluate the effect of parental
hypertension on children’s BP in infancy and childhood, the children
were divided into 3 groups on the basis of whether their parents were
normotensive or if they had 1 or 2 hypertensive parents (ie, adult
with mean BP during the study ⱖ140/ⱖ90 mm Hg or medication for
hypertension). All of the parents with ⱖ3 BP measurements during
the study were included in these analyses. In these analyses, the
study group (intervention/control) was used as a covariant. Effect of
parental borderline hypertension (BP: 130 to 139/85 to 89 mm Hg)
was studied alike. Fourth, the children were divided in 2 groups on
the basis of history of early (men ⬍60 years and women ⬍70 years)
coronary heart disease or cerebrovascular disease in their grandparents; BPs of these groups of children were compared with repeatedmeasures ANOVA.
Results were considered statistically significant at a value of
P⬍0.05. Statistical analyses were performed using the SAS Software
for Windows, release 9.1 (SAS Institute).
Results
Macronutrient and Micronutrient Intakes of the
Study Children Up to Age 15 Years
As reported before, intakes of fat and saturated fat were lower
in children of the intervention group than in those of the
control group through the study (P⬍0.001; Table 1). Intakes
of monounsaturated fat (as E%) did not differ between the
study groups (P⫽0.12), but children of the intervention group
had higher polyunsaturated fat intakes than the controls
(P⬍0.001). Dietary intakes of sodium (P⫽0.76) and calcium
(P⫽0.08) did not differ between the study groups, but intakes
of potassium (P⫽0.002) and magnesium (P⬍0.001) were
slightly but significantly higher in children of the intervention
group than in the controls (Table 1).
Impact of Age and Sex on BP
The systolic BP increased gradually from 92 mm Hg at 7
months to 110 mm Hg (mean) at 13 years in both sexes
(Figure 1). Diastolic BP was at the lowest at 5 to 8 years of
age and increased thereafter from 56 to 58 mm Hg to 60 to
62 mm Hg at 15 years of age (Figure 2). Boys tended to have
higher systolic BP than girls (P⫽0.058), and the mean (95%
CI) difference between the systolic BP of boys and girls was
0.8 mm Hg (95% CI: ⫺0.0 to 1.6 mm Hg). There was a
significant gender*age interaction in BP values (P⬍0.001);
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920
Hypertension
Table 1.
June 2009
Mean (SD) Dietary Intakes of Intervention and Control Children From 13 Months to 15 Years of Age
13 mo
Age Group
3y
6y
9y
12 y
15 y
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
Intervention
Control
No. of
subjects
510
481
429
414
363
358
295
309
266
287
248
276
Energy,
kcal†
955 (179)
981 (185)
1202 (214)
1229 (228)
1490 (248)
1497 (258)
1645 (305)
1719 (337)
1828 (365)
1847 (413)
1958 (504)
2022 (558)
P*
⬍0.001
Fat E%‡
26.3 (5.8)
27.8 (4.7)
30.3 (4.7)
32.7 (4.4)
29.6 (4.3)
32.4 (4.3)
28.7 (4.7)
32.1 (5.1)
30.5 (4.8)
31.4 (4.9)
30.5 (5.1)
31.6 (5.6)
⬍0.001
SAFA, E%
9.5 (2.9)
12.8 (2.7)
11.8 (2.4)
14.6 (2.6)
11.5 (2.2)
13.9 (2.4)
11.1 (2.5)
13.7 (2.8)
11.4 (2.7)
12.9 (2.7)
11.1 (2.4)
12.8 (3.0)
⬍0.001
MUFA, E%
9.4 (2.6)
8.8 (1.9)
10.2 (2.0)
10.5 (1.8)
10.6 (1.8)
11.0 (1.7)
10.9 (2.0)
11.0 (2.0)
11.1 (2.1)
10.7 (2.1)
10.9 (2.4)
10.6 (2.1)
0.12
PUFA, E%
5.2 (2.1)
3.9 (1.3)
5.5 (1.4)
4.8 (1.2)
5.3 (1.2)
5.0 (1.3)
5.7 (1.3)
5.2 (1.3)
5.8 (1.4)
5.3 (1.4)
5.9 (1.6)
5.4 (1.6)
⬍0.001
Protein, E%
17.8 (2.8)
17.4 (2.6)
16.3 (2.2)
15.6 (2.1)
16.4 (2.2)
15.8 (2.1)
16.4 (2.7)
16.1 (2.4)
16.9 (2.9)
16.6 (2.6)
17.8 (3.0)
17.3 (3.0)
⬍0.001
Sodium, mg
1533 (483)
1525 (512)
1897 (476)
1838 (484)
2290 (496)
2250 (535)
2196 (534)
2332 (595)
2739 (681)
2768 (685)
2973 (863)
3049 (931)
0.76
Potassium,
mg
2193 (506)
2161 (467)
2312 (477)
2200 (503)
2755 (574)
2596 (532)
2952 (613)
2884 (591)
3095 (728)
3063 (734)
3485 (971)
3375 (961)
0.002
Calcium, mg
779 (230)
807 (240)
862 (221)
836 (248)
1035 (267)
1007 (260)
1070 (306)
1127 (320)
1154 (368)
1181 (380)
1228 (426)
1274 (454)
Magnesium,
mg
188 (45)
184 (41)
199 (41)
188 (42)
241 (49)
225 (45)
262 (54)
253 (52)
277 (66)
273 (64)
308 (84)
302 (84)
0.082
⬍0.001
Intakes at ages 8 and 18 months and 2, 4, 5, 7, 8, 10, 11, 13, and 14 years are not shown.
*Difference between groups, by repeated-measures ANOVA.
this interaction was significant at ages 14 and 15 years. Thus,
after 13 years of age, the systolic BP was clearly higher in
boys than in girls. The overall diastolic BP did not differ
between sexes (P⫽0.95), but there was a significant
gender⫻age interaction (P⫽0.01) so that the boys had higher
diastolic BP than girls at 7 months of age.
lower diastolic BP than controls (P⬍0.001; Figure 2), and the
mean (95% CI) difference between diastolic BP of the
intervention and control children was ⫺1.0 mm Hg (95% CI:
⫺1.5 to ⫺0.4 mm Hg). The mean (SD) BPs, weights, heights,
and BMIs of the intervention and control children at 15 years
of age are presented in Table 2.
Effect of Dietary Counseling on BP
Effect of Parental Hypertension on Children’s BP
The children of the intervention group had lower systolic BP
than controls (P⫽0.018). The mean (95% CI) difference
between the systolic BP of the intervention and control
children was ⫺1.0 mm Hg (95% CI: ⫺1.7 to ⫺0.2 mm Hg;
Figure 1). The children of the intervention group also had
Of the studied children, 608 had normotensive parents, 281
had 1 hypertensive parent, and 36 had 2 hypertensive parents.
The systolic BP differed significantly among these 3 groups
of children (P⬍0.001; Figure 3). At 7 months of age, the
systolic BP of children with normotensive parents was
91.8 mm Hg (⫾13.2 mm Hg), whereas that of children with 2
140
130
Intervention girls
Intervention boys
Control girls
Control boys
70
65
120
110
mmHg
mmHg
Intervention girls
Intervention boys
Control girls
Control boys
100
90
60
55
80
70
50
7m 13m 2y 3y 4y 5y 6y 7y 8y 9y 10y 11y 12y 13y 14y 15y
Age
Figure 1. Mean (SE) systolic BP of intervention and control girls
and boys from 7 months to 15 years of age (P⫽0.018 between
intervention and control groups).
7m 13m 2y
3y 4y 5y
6y 7y 8y
9y 10y 11y 12y 13y 14y 15y
Age
Figure 2. Mean (SE) diastolic BP of intervention and control girls
and boys from 7 months to 15 years of age (P⬍0.001 between
intervention and control groups).
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Niinikoski et al
Blood Pressure and Saturated Fat in Childhood
921
Table 2. Mean (SD) BPs, Weights, Heights, and BMIs of 15-Year-Old Intervention and Control Children and Children With Either 2
Normotensive Parents or 1 or 2 Hypertensive Parents
No. of Children
Systolic BP, Mean
(SD), mm Hg
Diastolic BP, Mean
(SD), mm Hg
Height, Mean
(SD), cm
Weight, Mean
(SD), kg
BMI, Mean
(SD), kg/m2
Intervention girls
115
113.6 (10.2)
60.2 (6.0)
166.6 (6.0)
57.1 (8.0)
20.6 (2.5)
Control girls
137
114.8 (11.9)
61.9 (6.9)
165.7 (5.9)
57.1 (10.6)
20.7 (3.6)
0.38
0.048†
0.28
0.74
0.86†
Intervention boys
133
120.8 (13.2)
60.8 (7.2)
173.9 (8.2)
61.2 (11.8)
20.1 (3.2)
Control boys
139
122.0 (12.3)
62.7 (7.5)
174.2 (7.0)
62.7 (11.7)
20.6 (3.5)
0.42
0.045
0.78
0.24
Study Subjects
P*
P*
0.23
Children with
2 normotensive parents
608 (296 F, 312 M)
116.7 (12.3)
60.8 (7.1)
170.8 (8.0)
59.2 (10.9)
1 hypertensive parent
281 (138 F, 143 M)
119.9 (12.5)
62.4 (6.8)
168.9 (7.6)
60.0 (11.0)
21.0 (3.4)
2 hypertensive parents
36 (19 F, 17 M)
121.6 (12.8)
63.2 (5.8)
171.1 (7.6)
61.2 (11.7)
20.9 (4.0)
0.008
0.023
0.035
0.53
0.032
P‡
20.2 (3.1)
F indicates female; M, male.
*Data were equated by t test.
†Logarithmic transformation was used to normalize the distribution.
‡Data were equated by ANOVA.
hypertensive parents was 94.9 mm Hg (⫾10.5 mm Hg). At 15
years, the respective BPs were 116.7 mm Hg (⫾12.3 mm Hg)
and 121.6 mm Hg (⫾12.8 mm Hg; Table 2). The mean
diastolic BP of children with normotensive parents was
⬇3 mm Hg lower than that of children with 2 hypertensive
parents (P⬍0.001; Figure 4). The BP of the children with 1
hypertensive parent was between the BP of the children with
normotensive parents and that of children with 2 hypertensive
parents. BMIs of 15-year-old children with hypertensive
parents were slightly higher than BMIs of children with
normotensive parents (Table 2). Although the BPs of children
with 2 parents with borderline high (130 to 139/85 to
89 mm Hg) BPs tended to be higher than those of children
140
130
with normotensive parents this difference did not reach
statistical significance (P⫽0.35 for systolic and P⫽0.13 for
diastolic BPs; data not shown). The study group (intervention
or control) did not influence these results, ie, parental
hypertension affected childhood BP similarly in both study
groups.
Grandparents’ Vascular Disease and
Children’s BP
Of the studied children, 292 had ⱖ1 grandparent with either
early coronary heart disease or cerebrovascular disease,
whereas grandparents of 763 children had no early vascular
disease. The diastolic BP tended to be higher in children with
early grandparental vascular disease (P⫽0.051).
70
Both normotensive
One hypertensive
Both hypertensive
65
120
110
mmHg
mmHg
Both normotensive
One hypertensive
Both hypertensive
100
90
60
55
80
70
7m 13m 2y 3y 4y 5y
6y 7y 8y
9y 10y 11y 12y 13y 14y 15y
Age
Figure 3. Mean (SE) systolic BP from 7 months to 15 years of
age in children with normotensive parents, 1 hypertensive parent, or 2 hypertensive parents (P⬍0.001 between the groups).
50
7m 13m 2y
3y 4y 5y
6y 7y 8y
9y 10y 11y 12y 13y 14y 15y
Age
Figure 4. Mean (SE) diastolic BP from 7 months to 15 years of
age in children with normotensive parents, 1 hypertensive parent, or 2 hypertensive parents (P⬍0.001 between the groups).
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Hypertension
June 2009
Discussion
We recently published the 14-year follow-up results of
the STRIP Study and showed that saturated fat– oriented
counseling resulted in lower serum cholesterol concentrations, slightly decreased intake of total fat, and markedly
decreased intake of saturated fat (11 to 12 E% versus 13 to
14 E% in control children). We have now shown that
saturated fat–reduced diet since infancy decreases the
mean systolic and diastolic BP values of both girls and
boys by ⬇1 mm Hg.
The diastolic BPs were higher until 3 years of age in the
present study when compared with age- and height-adjusted
mean values presented in a recent working group report.1 BP
of ⬎120/80 mm Hg in adolescence was considered “prehypertensive” by the working group report.1 In late puberty, the
systolic BPs of the STRIP children were higher than recommended, because at 15 years of age, systolic BP was
⬎120 mm Hg in 51% of the boys and 29% of the girls. On the
other hand, the diastolic BP was ⬎80 mm Hg (also considered prehypertensive) in only ⬇1% of the adolescents.
Salt restriction during the first year of life significantly
delays the BP rise in childhood.9 STRIP intervention, not
being focused on salt or sodium intakes during the first years
of life, did not lead to lower salt consumption in children of
the intervention group than in controls up to age 5 years.19 In
the present study we have shown that the intakes of sodium
and calcium were not significantly influenced by the intervention. A minor increase in the intakes of potassium (⬇75
mg/d) and magnesium (⬇8 mg/d) was observed in children of
the intervention group, but impact on BP of such small
changes may not be detectable.
Quantity and quality of dietary fats influence BPs of
laboratory animals10 as well as of humans,11–14 even without
sodium restriction.14 A diet rich in monounsaturated fat
resulted in reductions in systolic (⫺2.2%) and especially
diastolic (⫺3.8%) BPs, but, interestingly, the favorable effects on BP disappeared at a total fat intake level ⬎37 E%.12
Exercise alone has been associated with 1% to 3% reductions
in both systolic and diastolic BPs,22 but the effects of the
Dietary Approaches to Stop Hypertension diet and weight
loss of several kilograms have been somewhat larger than
those with exercise alone.23
Fiber and protein intakes might also influence children’s
BP.24,25 In the STRIP Study, protein intakes were constantly
slightly higher in the intervention group than in the controls.
The intakes of fat and saturated fat of the intervention
children were lower, intakes of monounsaturated fat similar,
and intakes of polyunsaturated fat higher in children of the
intervention group than in controls. It is difficult to know
whether the lower BP values in children of the intervention
group were because of a lower intake of saturated fat, a higher
intake of polyunsaturated fat, a higher intake of protein, or a
combination of all of these.
Other than sodium consumption, obesity may be the most
important modifiable factor influencing the increase of BP
during childhood.1 Both obese children and adults have
higher BPs that their lean counterparts,26 and weight loss
associates with a decrease in BP.27,28 Central obesity is the
most important factor of insulin sensitivity, but it is also
17
influenced by dietary fat quality.29,30 The STRIP diet improved insulin sensitivity31 without differences in weights,
heights, and BMIs between the children in the intervention
and control groups.17 Thus, the 1-mm Hg difference in the
mean BPs between the intervention and control groups might
be attributed to improved insulin sensitivity rather than
decreased sodium intake.
The BPs of boys and girls are closely similar until
midpuberty, at which point BPs of boys tend to be higher
than those of girls.32 This age coincides with the age at
which also other cardiovascular risk factors (especially
high-density lipoprotein cholesterol) deteriorate in boys
when compared with girls.17 Although the BPs of the
intervention boys were significantly lower than those of
the controls, the pubertal BP increase could not be blunted
by the fat-oriented intervention. Studies in traditional,
nonindustrialized countries have shown that BPs do not
always increase with age in adulthood.33,34 In the STRIP
Study, BP increased with age along with increasing sodium
intake and reached the adult BP levels of low-sodium
cultures already at the age of 8 to 10 years.
The Fels Longitudinal Study showed that the risk of
developing hypertension at the fourth decade of life was 3.8
to 4.5 times more common in those 5- to 7-year-old boys and
girls who had BP at a single examination above that of
children who remained free of metabolic syndrome as adults.7
A single routine BP measurement in adolescence predicts
young adult hypertension (girls) and 10-year cardiovascular
risk (boys35). The impact of early BP on vascular health is
immense, because childhood systolic BP measured at ages 12
to 18 years independently associates with adult carotid artery
intima-media thickness 21 years later.8
BP is higher in children of hypertensive parents.3,4,36 van
Hooft36 showed that no clear differences existed in BPs
between 8-year-old children of parents with relatively high
BP compared with those of children with no family history of
high BP, but at 20 years of age, a 7-mm Hg difference in both
systolic and diastolic BPs was found. In the STRIP Study, we
have now shown that BPs in children of hypertensive parents
are higher than in those of normotensive parents through
childhood, and at late childhood, their BMIs are also slightly
higher.
Relative risk for cardiovascular disease is 1.23 for a
10-mm Hg increase in systolic BP.37 This relationship is
positive starting at the systolic BP level of 115 mm Hg and
even more so above 120 mm Hg. In hypertensive patients, a
5- to 6-mm Hg decrease in diastolic BP decreases the risk of
stroke and myocardial infarction by 38% and 16%, respectively.38 Therefore, a 1-mm Hg lower BP in children of the
intervention group, if maintained through lifetime or even
increased with age, might have an immense effect on future
vascular health.
There are some potential weaknesses in our study. The
reporting of grandparental vascular disease has possibly not
been accurate in all of the families. On the other hand, this
may even dilute the estimation of the effect of grandparental
vascular disease on children’s BP, because some true cases of
grandparental vascular disease may have been missed. Another possible weakness is the measurement of BP, which
Downloaded from http://hyper.ahajournals.org/ by guest on August 22, 2014
Niinikoski et al
was done only once at each visit until 7 years of age.
Moreover, the oscillometric BP monitor is not completely
accurate in estimating systolic or diastolic BPs.39 Clear
strengths of the present study include a very long follow-up
period, serial BP measurements, and accurate estimation of
dietary intakes.
Perspectives
The STRIP data show that supervised dietary counseling to
restrict saturated fat intake and to increase unsaturated fat,
vegetable, and fruit intake from infancy until 15 years of age
significantly decreases childhood systolic and diastolic BPs.
Children of hypertensive parents are already prone to higher
BPs in early childhood. These observations strongly emphasize the importance of primary prevention of hypertension in
the general child population and especially in those with
family history of vascular disease.
Sources of Funding
This study was supported by the Finnish Cardiac Research Foundation; Foundation for Pediatric Research, Finland; Academy of
Finland (grants 206374, 210238, 77841, and 34316); Mannerheim
League for Child Welfare; Yrjö Jahnsson Foundation; Sigrid Juselius
Foundation; Special Federal Research Funds for Turku University
Hospital; Turku University Foundation; Turku University Hospital
Foundation; Juho Vainio Foundation; Finnish Cultural Foundation;
and the city of Turku.
Disclosures
None.
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