When you fly these days, the airlines ply you with salty snacks — pretzels, munchy mix, peanuts and chips. For nervous fliers, these salty snacks may be just what you need to feel less anxious and a little more relaxed. A new study reported in the April 6, 2011 issue of The Journal of Neuroscience has found that at least in rats, a temporary rise in sodium levels can directly reduce stress. Researchers at the University of Cincinnati found that when they gave rats large doses of sodium and then exposed them to stressful situations, the rats secreted fewer stress hormones and their heart rate and blood pressure did not go up as much as in rats in the control group, where sodium levels remained “normal.” The rats that were given sodium also recovered from those stressful situations more quickly, settling back into normal blood pressure and heart rates.
Salt helps stress? Wait a minute — lots of people consider salt the enemy! This study struck me as so unusual that I immediately called its lead author, Eric Krause, PhD, in the university’s department of psychiatry and behavioral neuroscience to find out more about it. He explained that a temporary rise in sodium causes difficulty in regulating the body’s fluid balance, and this triggers two important shifts as the body goes into action to rebalance that fluid. First, the excess salt inhibits the action of the hormone angiotensin II, which plays a role in regulating blood pressure and is also a “stress hormone” that increases anxiety and drives the fight-or-flight response. Second, the fluid dysregulation prompts the release of the calming hormone oxytocin. So now, with sodium levels up, you have the stress hormone blunted — and with the soothing hormone on the rise, you have a group of much calmer rats.
Behind the Salt
Dr. Krause notes that certain kinds of drugs that many people take to treat high blood pressure called angiotensin II receptor blockers (ARBs) — including losartan (Cozaar) and valsartan (Diovan), among others — also have a calming effect because they inhibit the action of angiotensin II. Indeed, Dr. Krause said, there is good evidence from a number of studies that they provide the secondary benefit of stress relief.
As for eating pretzels and other salty snacks during anxious times, remember that a diet of salty foods is never good for health. And when I asked Dr. Krause if he would advise having a salty snack for comfort in times of stress, he responded frankly, “I work with animals, not humans. It may be that having a salty snack when stressed would provide a bit of relief.” But he added that salty food should definitely not be considered a treatment for anxiety — on balance, it’s just not good for us.