DALLAS (AP) -- Kids who load up on salty meals and snacks get thirsty, and too often they turn to calorie-filled sodas. So maybe cutting back on the salt is a good way to cut the calories. That's the idea coming from a British study published Wednesday in an American Heart Association journal.

Salt is "a hidden factor in the obesity epidemic," said Graham MacGregor, a co-author of the study by researchers at St. George's University of London.

And researchers say all that salt isn't coming from the salt shaker: About 80 percent comes from manufactured food.

"Most people think that sodium comes from the salt shaker. The salt shaker contributes less than 10 to 15 percent," said Dr. Myron Weinberger, a professor of medicine at Indiana University School of Medicine.

"Fast foods, for example, are just loaded with sodium. Processed foods are all very high in sodium," said Weinberger, who wrote an editorial related to the study published in the online journal Hypertension.

Not only could less salt translate to fewer soft drinks and therefore fewer calories, but a modest reduction in salt has already been shown to lower blood pressure, which increases the risk of later-in-life heart attack and stroke, researchers say.

Also, several studies have shown a link between sugary soft drinks and obesity in children.

Reducing salt in manufactured foods can be done gradually, without the public even noticing, said Dr. Feng He, lead author of the study and cardiovascular research fellow at St. George's. She said a 10 to 20 percent reduction in salt isn't even detectable.

"It's important for the food industry to make a reduction," she said.

The study suggested that cutting in half the amount of salt British children consume -- a decrease of about half a teaspoon a day -- would lead to an average reduction of about 18 ounces of sugar-sweetened soft drinks per week.

The study was based on diet data from Great Britain's National Diet and Nutrition Survey. Researchers looked at 1,688 British boys and girls -- ages 4 to 18 -- over a seven-day period in 1997.

They noted that the amount of salt eaten might be underestimated in the study because it didn't include salt added during cooking or at the table. The researchers also found that more than half the fluids drunk by the children were soft drinks, and more than half of those were sugar-sweetened.

MacGregor, a professor of cardiovascular medicine at St. George's, says the study results should apply to kids in the U.S. as well.

The United Kingdom began a government-led campaign to cut salt consumption in 1996 and researchers say more recent studies show that salt intake has already decreased.

In the United States, the Food and Drug Administration is taking public comment until March 28 on a consumer group's proposal to restrict the amount of salt in processed foods, among other options. And the American Medical Association has urged the government to require strong labeling of high-salt foods because if salt's connection to high blood pressure and heart problems.

Experts note that it will take more than cutting salt to get overweight kids in shape: healthy eating and exercise are needed as well.

"It's another piece of the puzzle," said Dr. Pamela Sayger Cava, pediatric cardiologist at the Herma Heart Center at Children's Hospital of Wisconsin. "The kids have to be active. They have to have more water, less soda. They have to eat less fast food."

MacGregor said that parents should look at food labels. And they should make sure children eat more fresh fruits and vegetables without adding salt, which stimulates the brain to want more fluid.

"Thirst is one of the most basic instincts. When you get thirsty, you have to drink," MacGregor said.

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