Low birth weight may increase adults' salt sensitivity

Elderly adults who had a low birth weight may be more sensitive to the blood-pressure increasing effect of salt in their diets, according to new research.

The finding supports past studies that found connections between low birth weight, high blood pressure, sensitivity to salt intake and hypertension. As such, those who had low birth weight should consider reducing their salt consumption, researchers recommended in a paper published in the American Journal of Clinical Nutrition.

In a study of 1512 people born between 1934 and 1944 in Finland, adults who weighed 3050 grams or less at birth were susceptible to a 2.48-mm Hg systolic blood pressure increase for every gram of salt they ingested up to 10 grams, researchers reported (P=0.025).

The findings

Of those who ingested more than the 10-gram daily average, those with low birth weight had 4.72-mm Hg higher systolic blood pressure (P<0.001). Birth weight had no effect on diastolic blood pressure in either group and those with higher birth weight were not susceptible to salt's effect on blood pressure, they found.

Also, men and women were affected equally.

"Even though the modifying effect of birth weight on the association between salt intake and SBP was modest, it might well have public health implications," wrote Dr Mia-Maria Perala, at the National Institute for Health and Welfare in Helsinki, Finland and her team.

The group

The study group was randomly selected from the Helsinki Birth Cohort Study of 4630 men and 4130 women. Multivariate regression models yielded the statistical analysis.

To explain their results, the researchers suggested a possible mechanism for the salt sensitivity. Low birth weight could stem from foetal under nutrition, they wrote, which may reduce the number of nephrons and increase the rate of glomerular filtration and, consequently, the risk of glomerulosclerosis and high blood pressure.

The findings support the hypothesis that adult disease is programmed early, the researchers concluded. (Reuters Health/ November 2010)

Read more:
Less salt in teens, healthier adult
Top 10 foods with hidden salt
Salt bad for heart, stroke risk
Do not pass the salt

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