What about the implication that kids would be better off if they simply cut back on their salt intake? Governmental organizations including the CDC and IOM advocate for population-wide salt reduction, but some researchers question the science behind these policies. "Cutting back on salt does reduce blood pressure, but it may not reduce the risk of dying early," explains Katarzyna Stolarz-Skrzypek, a cardiologist at Jagiellonian University Medical College in Poland.
In a 2011 study published in JAMA The Journal of the American Medical Association, Stolarz-Skrzypek and her colleagues compared the urinary sodium levels of 3,681 people with their risk of dying over the course of eight years. They found, surprisingly, that the more sodium their subjects ate, the less likely they were to die. In particular, the death rate among those eating the least sodium was 4.1 percent, but it was only 0.8 percent among avid salt consumers.
One factor behind this strange trend is that low-salt diets do more than just lower blood pressure. "Cutting sodium can cause other physiological changes such as increased resistance to insulin, which can set the stage for diabetes and increase the risk of death from heart disease," Stolarz-Skrzypek says. "Too little sodium can also increase sympathetic nerve activity, which raises the risk of heart attacks, and boost the secretion of aldosterone, a hormone produced by the adrenal gland that is bad for the cardiovascular system." A 2011 review published by the Cochrane Collaboration, an international, independent, not-for-profit research organization funded in part by the World Health Organization, concluded that low-salt diets are associated with "increases in some hormones and lipids, which could be harmful if persistent over time."
Looked at another way, the CDC study suggests that parents of overweight and obese kids should focus on weight loss, not salt reduction. Multiple studies in both adults and children suggest that weight has a bigger effect on blood pressure than salt does, and once kids reach a healthy weight, eating too much salt may not cause problems. Plus, going from obese to an appropriate weight reduces not only blood pressure but also the risk for conditions such as cancer, depression and type 2 diabetes. Shedding pounds isn't easy, but considering that an estimated 75 percent of our sodium intake comes from store-bought processed foods rather than what is added during cooking or at the dinner table, cutting back on salt isn't either—and ultimately, doing so may not be as beneficial for us as we think it is.