The association between salt intake and adult systolic blood pressure is modified by birth weight.
BACKGROUND
Epidemiologic evidence suggests that prenatal growth influences adult blood pressure. Nutritional factors, including salt intake, also influence blood pressure. However, it is unknown whether prenatal growth modifies the association between salt intake and blood pressure in later life.


OBJECTIVE
Our aim was to examine whether the relation between salt intake and adult blood pressure is modified by birth weight.


METHODS
We studied 1512 participants of the Helsinki Birth Cohort Study who were born between 1934 and 1944. Information on birth weight was abstracted from birth records, and preterm births were excluded. During a clinical study, at the mean age of 62 y, blood pressure, weight, and height were measured. Diet was assessed with a validated food-frequency questionnaire. The relation between salt intake and blood pressure was tested by a piecewise multivariate regression analysis with the best fitting breakpoints to birth weight and salt intake.


RESULTS
An inverse association was observed between birth weight and systolic blood pressure (SBP) (P = 0.02). No significant association between salt intake and SBP was observed in the whole study population. Of those whose birth weight was ≤3050 g, a 1-g higher daily salt intake was associated with a 2.48-mm Hg (95% CI: 0.40, 4.52 mm Hg) higher SBP (P = 0.017) until the saturation point of 10 g. Of those whose birth weight exceeded 3050 g, SBP was not significantly associated with salt intake. For diastolic blood pressure, no significant relations were observed.


CONCLUSIONS
Adult individuals with low birth weight may be particularly sensitive to the blood pressure-raising effect of salt.
Department of Lifestyle and Participation, National Institute for Health and Welfare, Helsinki, Finland. mia.perala@thl.fi
Mia-Maria
MM
Perälä
Elena
E
Moltchanova
Niina E
NE
Kaartinen
Satu
S
Männistö
Eero
E
Kajantie
Clive
C
Osmond
David J P
DJ
Barker
Liisa M
LM
Valsta
Johan G
JG
Eriksson
D001724:Birth Weight; D001794:Blood Pressure / Q000187:drug effects*; D015331:Cohort Studies; D004034:Diet Surveys; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017673:Sodium Chloride, Dietary / Q000009:adverse effects*; D011795:Surveys and Questionnaires
D017673:Sodium Chloride, Dietary