Kids who have less salt in their diets also consume fewer sugared soft drinks, researchers here said. Each reduction of 1 g/day in salt intake was associated with a reduction of 27 g/day of sugar-sweetened soft drinks among 4- to 18-year-olds.
The finding emerged from a cross-sectional study of 1,688 boys and girls in Britain who recorded everything they ate and drank, by weight, for one week.
The researchers suggested that reducing children’s salt intake would cause them to consume fewer calories in soft drinks, therefore helping to reduce childhood obesity. It might also improve their cardiovascular health directly, since salt intake is correlated with blood pressure.
Dr. He and colleagues determined that mean salt intake rose with age, from 4.6 g/day (SD 1.5) among 4-year-olds to 6.8 g/day (SD 2.1) for 18-year-olds.
The researchers did not count salt added during cooking or at the table. "The majority of salt intake is from salt already hidden in food, i.e., added by the food industry," they wrote.
The researchers found that soft drinks accounted for more than half of fluid consumption among most age groups for girls and boys, except for 17-year-olds. Taking all of the participants together, 56% of total fluid intake was in the form of soft drinks, of which 55% were sugar-sweetened and 45% were low-calorie.
Consumption of low-calorie soft drinks fell by about half as children grew older and consumption of soft drinks containing sugar increased slightly.
The researchers also found a highly significant association between salt intake and total fluid consumption. They calculated a partial correlation coefficient of 0.33 and a beta value of 100 g/day (SD 7) of fluid consumption per gram per day of salt intake (P0.001), after adjusting for age, sex, and body weight.
Adjusting for exercise made almost no difference in the strength of the correlation.
When the researchers compared salt intake with sugar-sweetened soft drink consumption, they also found a significant correlation, with a coefficient of 0.12 and beta value of 27 (SD 5) (P0.001), after adjusting for age, sex, and body weight.
"If salt intake was reduced by half in all children aged 4 to 18 years in the United Kingdom (i.e., a mean decrease of 3 g/d), there would be an average reduction of 81 g/d in the consumption of sugar-sweetened soft drinks per child, which is equivalent to a reduction of 2.3 soft drinks per week," Dr. He and colleagues wrote.
In turn, they added, the reduced soft-drink intake would translate to 61 fewer grams of sugar and 244 fewer kilocalories each week.
Per-capita consumption of soft drinks is similar in Britain and the United States, the researchers said. Dr. He and colleagues said reductions of 10% to 20% in the salt content of processed foods "cannot be detected by the human salt taste receptors and do not cause any technological or safety problems either."
They said prospective studies and other research have demonstrated that changes in salt intake lead to altered beverage consumption, including sugary drinks.
There are direct cardiovascular benefits to reduced salt intake as well, the researchers said.
They noted that, in Finland, systolic and diastolic blood pressure has declined by 10 mm Hg since the country began a national effort to reduce salt intake by its citizens in the 1970s.
Moreover, they said, stroke and coronary heart disease mortality have fallen by 75% to 80%, even though average body mass index and alcohol consumption have risen.
Great Britain now has a policy to reduce salt content of processed foods. However, Dr. He and colleagues said "some members of the food industry outside the U.K." have resisted compliance, in part to protect soft drink sales.
"Some soft drink companies own large snack companies that specialize in highly salted snacks," they said.
"However, they should not be allowed to stand in the way of a reduction in salt intake, because this reduction would have major benefits to the health of the whole population and, particularly, to children in potentially preventing the development of high blood pressure and obesity, thereby reducing the appalling burden of cardiovascular disease later in life," the researchers concluded.
He F, et al., "Salt intake is related to soft drink consumption in children and adolescents: a link to obesity?"Hypertension 2008; 51: 629 – 634.
Weinberger M, "Are children doomed by what they eat and drink?," Hypertension 2008; 51: 615 – 616.