The debate over the dangers of a high-salt diet, particularly for older Americans, is nothing new. It's been raging for decades, but a spate of conflicting studies in the past few months has many saying "enough already."
Last month's article in Scientific American basically summed it up with the exasperated headline, "It's time to end the war on salt." The writer — who looked at the research behind our salt fears — argued that the long, zealous campaign to get all of us to reduce our salt consumption has little basis in science.
And some notable experts agree.
Cardiologist Steven Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic, says there's no question that those with high blood pressure or heart problems should cut back on salt. But the quality of scientific evidence is still too weak for policymakers to insist that low sodium is right for everyone, regardless of their overall health.
"The evidence is observational. It's not based on randomized clinical trials that are the gold standard," he says. "So we're in the dark. We don't have good quality data, so we just don't know."
Michael Alderman, M.D., of the Albert Einstein College of Medicine in New York and former president of the International Society of Hypertension, also has repeatedly argued for caution in the nation's push to reduce sodium.
In medical journal commentaries over the past decade, Alderman has detailed the seesawing results of studies investigating the link between salt and heart disease.
He explains the reasoning behind the country's low-salt push this way: If reducing sodium reduces blood pressure — a medical fact — and high blood pressure causes strokes and heart attacks — another truism — then obviously reducing sodium will reduce heart problems and deaths.
But that kind of leap-of-faith assumption is problematic, Alderman writes.
Despite decades of research, no study has clearly proved that lowering salt consumption will save lives. For every study that seems to show that high-sodium leads to poor health, another one disputes it.
A perfect example of this occurred just last month. An analysis by British researchers of seven studies involving 6,250 people found no strong evidence that reducing salt reduced the risk of dying or getting heart disease. The study was published in the American Journal of Hypertension.
Two weeks later, another research group challenged the findings, saying a reanalysis of the same data did indeed show that sodium raises blood pressure, which in turn raises the risk of stroke and heart attacks. The more people can lower their daily salt intake, the more their blood pressure will fall, which is a good thing, the second group argued in a commentary published in the medical journal the Lancet.
The debate, says Nissen, is not over whether salt is bad for those with high blood pressure, heart disease or kidney disease. The question is, should restricting salt be a blanket recommendation for everyone, even those with normal blood pressure?
If you ask federal health officials, the answer is unequivocally yes — everyone can benefit by reducing their salt, especially older Americans.
The government's 2010 dietary guidelines for Americans recommend limiting total salt intake from all sources to 1,500 mg a day (less than a teaspoon) for people 51 and older, African Americans and those with high blood pressure, diabetes or chronic kidney disease. Most Americans now consume more than twice that much.
If nothing else, the guidelines advise, consumers should at least look at the food labels of the products they buy and pick the brands that have less sodium. Americans get nearly 80 percent of the salt they consume from processed and restaurant food, not from the salt they add when they're cooking at home.
The American Heart Association is even more adamant, issuing a "call to action" this past January for consumers, health professionals, the food industry and the government to "intensify efforts to reduce the amount of sodium Americans consume daily."
The association goes further than the government, recommending that all adults, regardless of age, consume no more than 1,500 mg of sodium to reduce the risk of stroke, heart attacks and kidney disease. Doing this, the association says, will save on health care costs and save lives.
But then a recent study of 12,000 adults by researchers with the federal Centers for Disease Control and Prevention, published in the Archives of Internal Medicine, found that the ratio of sodium to potassium may be a more important factor in determining risk of death than sodium alone. Researchers found that those who ate a high-salt, low-potassium diet — meaning heavy in processed and restaurant food — had a 50 percent higher risk of death. Those who had a higher potassium intake (typical of fresh foods) had a lower risk of death.
Obviously, for those who have high blood pressure, heart or kidney disease, "restricting salt is the right thing," Nissen says. Following a low-salt diet can help them avoid having to take additional medicine, which can have side effects, he explains.
More importantly, for those with congestive heart failure, cutting back on salt "will keep you out of the hospital."
But for older Americans with normal blood pressure, sticking to a low-salt diet can be tough, especially because we've all grown accustomed to the salt levels in packaged and restaurant food, so low-salt foods taste bland. Campbell's soup recently announced that they were adding the salt back into their line of low-sodium soups because the soups weren't selling.
Marion Nestle, a professor of nutrition and public health at New York University, provides still another twist in the salt story mystery. She says a portion of the population is sensitive to salt, so cutting their salt lowers their blood pressure. But another, possibly larger, percentage of people can eat salty food and their blood pressure isn't affected. In other words, a one-size salt shaker doesn't fit all.
Still, Elena Kuklina, M.D., with the CDC's division of heart disease and stroke prevention, insists that "nearly everyone benefits from reduced sodium consumption."
Kuklina, who's also an author of the CDC's recent potassium-sodium study, says Americans over age 50, "even those with normal blood pressure," should consume no more than the government-recommended 1,500 mg of salt a day.
"Eating less sodium along with more potassium can help prevent or control high blood pressure," she says.
To make sure older Americans get enough potassium in their diet, she urges them to eat fresh, high-potassium foods such as spinach, grapes, carrots and potatoes.
Or think about this: Cook more from scratch and eat out less. That's an easy way to cut back on salt without sacrificing flavor.
Candy Sagon writes about health and food for the AARP Bulletin and online in her blog, HealthyCandy.