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Sonia Angell has a thing about salt. She thinks about it much of her day. When she talks on the phone from her office in Lower Manhattan, she speaks with increasing passion about the mineral — specifically, getting rid of it. "It's a nutrient that we are eating in excess," she says, "to the point where it has become dangerous."
Dr. Angell is a general internist with a master's degree in public health, and she is in a good position to act on her conviction: She runs the Cardiovascular Disease Prevention and Control Program at the New York City Department of Health and Mental Hygiene (DOHMH), the same place that caused a huge uproar a few years ago when it mandated that all city restaurants get rid of artery-clogging trans fats. Initially spurred on by former DOHMH Commissioner Thomas Frieden, now director of the Centers for Disease Control and Prevention, she and the Department of Health have taken on salt because they and many others in the scientific community hold that eating too much sodium chloride, or salt, causes heart attacks, strokes, and deaths. So in 2008, the DOHMH spearheaded a collaboration called the National Salt Reduction Initiative — a group of more than 45 cities, states, and powerful national and international health organizations, including the American Heart Association, the American Medical Association, and the World Hypertension League — to prevent disease and death by gradually siphoning off a lot of salt from the country's food supply.
The big glitch in this impressive-sounding plan: Not everyone in the medical community agrees that limiting salt nationwide will prevent these problems. "Is sodium important to most people's health? Is this a battle worth fighting for most people? The answer is no," says Norman Hollenberg, M.D., Ph.D., a kidney specialist and blood pressure researcher at Harvard Medical School who has edited books like the Atlas of Hypertension. Many doctors, including journal editors, cardiologists, and medical association presidents, say that while it makes sense for some people with high blood pressure to lower their salt intake, current science doesn't show that the rest of us will reap much, if any, benefit from this sweeping policy. In fact, these researchers believe the initiative is being foisted on the American public without sufficient justification — and could even be dangerous.
They say that curtailing salt in the food supply may wreak unforeseen harm, and point out that no clinical trials in the general population have linked salt to heart disease or death. Past public health recommendations, they note, have backfired because they were implemented before proper studies were conducted (one example: switching from butter to trans-fat-loaded margarines — which proved to be worse). Salt is a cheap, tasty additive and preservative. "There are reasons food companies put it in their products. Now they have to find substitutes, and we don't know what impact the substitutes will have," says Hillel Cohen, Dr.P.H., M.P.H., an epidemiologist at the Albert Einstein College of Medicine in the Bronx who studies hypertension. "Wouldn't it be nice to have some information before going ahead with a health policy that will affect millions of Americans?"
The Rise and Fall of Salt
Salt has been a dietary player for at least 10,000 years, since humans began using it to season their meals. About 5,000 years ago, the Chinese discovered it could preserve food, allowing people to survive long, cold winters with a stash of salted supplies. Civilizations traded in it, cities like Venice and Oslo were built on it, and wars have been fought over it. Romans salted their greens, originating the word "salad"; even "salary" ("salt money") comes from the word salt.
At its most basic level, our bodies need salt because sodium helps our brains transmit signals and keeps our cells and the fluid surrounding them in balance. Our intake reached its peak in the late 1800s, when salt was used to preserve foods for storage, and declined as refrigeration became more widespread in the early 20th century. By mid-century, however, when packaged and convenience foods began to replace fresh foods in our diets, the amount of sodium we consume began to climb; today we get nearly 80 percent of our daily dose not from the shaker, but from processed foods. (According to national diet-tracking studies, in the late 1980s salt consumption leveled off — and has remained — at about 1½ teaspoons, or roughly 3,500 mg, of sodium a day.)
Roughly a century ago, in a study of people with hypertension, French doctors found for the first time that when subjects ate the equivalent of about 4,100 mg of sodium per day, their blood pressure rose, and that when they cut back, it dropped. Over time, a hypothesis developed linking high salt consumption with high blood pressure, or hypertension: In general, when we take in large amounts of sodium, our bodies need to conserve more water to maintain a stable concentration in the fluids. More water would mean more blood, and more blood, higher pressure within our vessels. The association between salt and blood pressure is critical because high blood pressure has been shown to increase the risk of heart disease. Large volumes of blood straining against vessel walls can make them weak and more susceptible to damage, playing a role in heart attacks, strokes, and possibly death. It's this linkage — from sodium to hypertension, and then from hypertension to heart attacks, strokes, and death — that's behind the crusade against salt.
The Fickle Effect of Sodium
There's little question that for some people who have high blood pressure — nearly a third of Americans — slashing sodium by about 1,800 mg a day does reduce blood pressure — about 5 points for systolic, about 3 to 4 for diastolic, according to one large review. That's like going from a reading of 145/90 to 140/87 — usually not enough to achieve a healthy blood pressure, but helpful nonetheless.
But in people who have normal blood pressure, trying to reduce sodium intake by heroically cutting back on salt reduces blood pressure readings a mere one to two points, on average. The cuff at your doctor's office might not even detect such a tiny difference. And studies suggest that over time, these blood pressure reductions tend to get smaller. One theory as to why: The body adjusts to the lower salt level. Indeed, blood pressure reductions like these are similar to, or even less than, those that might result from other, perhaps easier, lifestyle changes: Eating three portions of whole grains a day can drop systolic blood pressure 6 points; drinking one less sugary drink daily, 1.8 (systolic) and 1.1 (diastolic) points; and losing seven pounds, 1.4 and 1.1 points.
Yet public health experts think sodium's one- to two-point reduction is reason enough to launch their salt-cutting campaign. "With a small reduction for everyone, we'll get a huge benefit for society at large," says Dr. Angell, who estimates that the nationwide initiative will save as many as 150,000 lives each year — a number that the naysayers claim is built on untested assumptions.
How Low Can We Go?
Last April, after extensive talks with food manufacturers, Dr. Angell and the DOHMH published voluntary limits on sodium in 62 categories of packaged food (breakfast cereal, canned soup, and more) and 25 categories of restaurant food (hamburgers, fries, muffins) to lower sodium throughout the food supply. Sixteen food companies and restaurant chains, including Heinz, Unilever, Kraft, and Subway, have already signed on. The goal: a 25 percent reduction over the next five years, which is in line with the American Medical Association's call for a total of 50 percent over the next 10.
Dr. Angell calculates that this should get us closer to 2,300 mg, the maximum amount of sodium recommended in the current Dietary Guidelines for Americans, 2005, the government's official road map for building healthy American diets; it covers everything from school lunches to dietitians' advice to their clients. But the new 2010 guidelines, anticipated for release at the end of the year, dump this old number for an even lower one: 1,500 mg — about two-thirds of a teaspoon of salt a day. That amount is the so-called "adequate intake" — the minimum our bodies need to function and to maintain good health.
Why drop so low? The number one reason, says Lawrence Appel, M.D., M.P.H., professor of medicine at Johns Hopkins University and member of the 2010 U.S. Dietary Guidelines scientific advisory committee that recommended the new sodium level, is the direct relationship between sodium and blood pressure: The less you take in, the lower your blood pressure. (Other researchers have a problem with this, saying it's not that simple.) In the 2001 DASH (Dietary Approaches to Stop Hypertension-Sodium) trial, which tested the effects of a healthy, monthlong, low-sodium diet in people with high and borderline-high blood pressure, subjects' blood pressure dropped considerably when they consumed about 1,500 mg of sodium a day. In addition, "you're dealing with a chronic problem that develops over time," he says. "The idea of somebody just waiting until they have hypertension and then flipping into a low-sodium diet is somewhat like saying, well, let's just wait until you get your first heart attack and then we'll start telling you about saturated fat."
But drastically cutting sodium to 1,500 mg a day astounds some physicians. "The goal is completely unrealistic. This is far too low," says Neils Graudal, M.D., a Danish researcher who has published several large, influential research reviews showing that cutting sodium affects a lot more than just blood pressure. "There's no evidence that directly links low sodium intake to better survival," he adds. Furthermore, he thinks it's unrealistic to expect anyone to actually adhere to the new guideline, considering that one store-bought corn muffin (590 mg) and a cup of chicken noodle soup (840 mg) come in just under the limit. A dinner out can cost you a couple of days' worth of sodium: At Chili's, an Asian Salad with Grilled Chicken has 2,700 mg, and a Cajun Pasta with Grilled Shrimp, 3,200. Prepared salad dressings can have 505 mg per serving; ketchup, 167 mg per tablespoon; pasta sauce, 1,054 mg per cup. Even with the Initiative's reductions, it will be hard to find things to eat.
What's more, doctors and public health experts have long assumed that if we all just knew how to lower the salt and we were in a food environment conducive to eating less of it, we'd cut back. But the findings of a recent study on sodium appetite — how much our bodies naturally "want" — contradict that assumption. When researchers at the University of California, Davis, and Washington University in St. Louis looked at the sodium intakes of 19,151 people in 33 countries with vastly different cuisines, they found the amount people typically consumed fell within a narrow range (2,691 — 4,876 mg/day; the average was 3,726 mg/day); even when scientists tried to get people to lower their sodium to 2,300 mg, the subjects couldn't do it, and they ended up at about 2,800 mg/day. The researchers hypothesize that we might have evolved an appetite for the mineral along with a physiological set point that ensures our body's need for sodium in multiple systems is satisfied.
The Jury's Still Out
The U.S. isn't the first country to launch a plan to ferret the sodium out of its citizens' diets. Britain, where more than 70,000 people die from coronary heart disease and 110,000 people suffer a heart attack each year, instituted a sodium-reduction initiative back in 2004, spearheaded by its Food Standards Agency (FSA — broadly similar to the food sector of our FDA). Two years later, the FSA lowered the voluntary salt-reduction targets for around 80 categories of packaged food — bacon, breads, and cereals, as well as convenience and snack foods — which were to be achieved by 2010. Now the aim for 2012 is to reduce adult intake to around 2,400 mg of sodium a day.
As a result of the initiative, sodium has been lowered by around 33 percent in packaged bread, 49 percent in breakfast cereals, and 21 to 50 percent in processed cheese, among other reductions. "The brilliant thing is, people don't have to change their diets, because the salt has been surreptitiously reduced without their realizing it," says Graham MacGregor, M.D., a hypertension expert and one of the driving forces behind the British salt-slashing initiative. "You have to be something of a nut if you really want to reduce your salt. You have to cook at home and buy all fresh fruits and vegetables, which for the average consumer is a complete impossibility." But are people actually eating less salt? The FSA's survey work suggests that it has reduced the population's intake by 10 percent between 2000 and 2008. But researchers from the University of California, Davis, and Washington University in St. Louis, writing in the Clinical Journal of the American Society of Nephrology, questioned that finding. They pointed out that when all the most rigorous studies, not just those conducted in 2000 and 2008, are considered, salt intake has risen and fallen over time, resulting in no overall difference in 24 years: Britons ate about 3,400 mg of sodium a day in 1984 and about 3,400 mg in 2008, with levels dipping and rising no more than 400 mg. The FSA calculates that the reductions are preventing around 6,000 premature deaths a year, but no actual study has been conducted.
Where Are the Trials?
The most compelling argument against the Initiative, say Drs. Graudal and Cohen, among others: There has never been a randomized, controlled clinical trial (the scientific-research gold standard) examining the effect that consuming 1,500 mg of sodium a day — or any level, for that matter — has on the risk of heart attack, stroke, or death. While studies have shown that lowering blood pressure reduces those risks, "we really have no idea if cutting back on salt protects our hearts, too," says Dr. Cohen, nor do we know if the converse is true — whether people who eat higher amounts of sodium are more likely to have a heart attack or stroke, or to die.
Salt-reduction proponents point to the Trials of Hypertension Prevention follow-up study, which began as two clinical trials of more than 4,500 30- to 54-year-olds with slightly elevated blood pressure who were given either intensive counseling to cut back on sodium or only general guidelines for healthy eating. A year and a half to three to four years later (the end of each trial), the sodium-reduction group had only a one- to two-point drop in blood pressure compared with the control group. But 10 to 15 years later, the researchers caught up with some of the study's participants and found that those in the low-salt group were 25 percent less likely to have suffered a heart attack during the intervening years, suggesting that the amount of salt one eats might be linked with a real health outcome like heart attacks, not just high blood pressure. Compelling as this is, however, the naysayers point out that there was no significant difference in the number of deaths between the two groups. In addition, not all the original participants could be found, and the study was, in fact, no longer a clinical trial, but a less rigorous observational study (which can't determine cause and effect).
The only other general-population studies on humans that looked at sodium's connection to heart attacks and strokes have been observational, and those results have been mixed: Some showed that people who ate more sodium had more heart attacks, while others found no link; a few even found that people who ate less sodium had more heart attacks. Even if you include only the studies showing a link between high salt and increased cardiovascular disease, "it's observational data. I wouldn't make a clinical decision on it, and I sure as hell wouldn't make a decision on it for 300 million people," says Michael Alderman, M.D., a hypertension researcher at Albert Einstein College of Medicine and vocal critic of the salt-lowering efforts.
Scientists say that sodium may affect insulin and parts of our nervous system, as well as fats like cholesterol, and that the kidneys have their own blood pressure/sodium-regulation system (the renin-angiotensin system). All of these factors affect heart health, too, though their relationship with sodium isn't as well studied as blood pressure's, so they remain in the shadow of the better-known heart disease risk factor. "The crux of the problem is that when you reduce sodium intake, lots of things happen. Some are good, and some are bad," says Dr. Alderman. "The effect on health will be the net effect of all of those conflicting influences."
Indeed, a 2003 in-depth review of the evidence and a soon-to-be-published update that analyzed the research on many of these factors found that low sodium affects multiple systems in our body: As the mineral goes down, levels of cholesterol, triglyceride, renin, and other health indicators go up. The resulting health effects are not yet known. Coauthor Dr. Graudal concludes his report: "The magnitude of the effect in Caucasians with normal blood pressure does not warrant a general recommendation to reduce sodium intake." Another recent meta-analysis from British researchers led by Lee Hooper, Ph.D., at the University of East Anglia arrived at a similar conclusion: "Intensive interventions, unsuited to primary care or population prevention programs, provide only minimal reductions in blood pressure during long-term trials." Translation: For people with normal blood pressure, drastic salt reductions aren't necessary, and they probably won't work.
"I wish the magic bullet were true; I wish it were that simple," says Dr. Alderman. "But it is naive to assume that you can go from an effect on blood pressure, pretend the others don't exist, and then extrapolate what the optimal benefit might be. That's a hope, or faith, but it's not science." "Do you know the Danish tale The Emperor's New Clothes?" says Dr. Graudal. "I think I and a few others are the boy saying the emperor hasn't got any clothes on."
Doing a clinical trial would answer many of the lingering questions. If we were certain that lowering salt reduced cardiovascular disease in the general population, we could adopt policies like the one spearheaded by New York City with a clear conscience. But some researchers say that a trial would be either a waste of time, too expensive, unethical, or impossible. "The possibility of a randomized controlled trial is not likely in the future," says rear admiral Penelope Slade-Sawyer, a deputy assistant secretary for health in the Department of Health and Human Services, who helped put together the Dietary Guidelines 2005. "It would be terrifically expensive, and I really don't think it's necessary." Dr. Angell notes, "One would argue at this point [that a trial is] unethical given all the amassed data that shows that high sodium is associated with high blood pressure and high blood pressure is associated with heart attack and stroke."
Yet without such studies and definitive proof of benefit, we all become test subjects. "It's an experiment any way you do it, whether it's on 300 million people [via public policy] or on 10,000 [in a randomized controlled trial]," says Dr. Alderman. It has happened before. Decades ago, Dr. Cohen notes, when studies suggested that saturated fat was bad for our cardiovascular systems, we were encouraged to cut it from our diets. Manufacturers and restaurants switched to partially hydrogenated oils instead of animal products, and families started eating margarine instead of butter. "It was 20 years or more before scientists realized that in propagandizing people to eliminate butter from their diet and replace it with stick margarine and trans fats, we might be doing more harm than good," says Dr. Cohen. Those trans fats have proved worse for our hearts than butter's saturated fat.
There are other examples: Tobacco companies added filters to cigarettes and created "light" cigarettes to make them healthier, but people just puffed harder or smoked more, and kept inhaling carcinogens and additives. In the 1950s, doctors told women to limit their weight gain during pregnancy to avoid preeclampsia (high blood pressure, fluid retention, and kidney problems), resulting in an increased number of underweight babies and infant deaths; more recently, the Dietary Guidelines encouraged Americans to eat low-fat foods and more carbohydrates, and now researchers believe this has contributed to obesity. "Respected authorities instituted reasonable ideas without having the evidence to know whether their policies might backfire," Dr. Alderman wrote in a February 2009 editorial in the New York Times. Perhaps the best example involves hormone replacement therapy. Doctors gave HRT to women during and after menopause because replacing the estrogen lost during menopause made logical sense and was intuitively appealing (let's make women "young" again), and observational studies suggested that women who took hormones had a 40 to 50 percent reduction in coronary heart disease risk compared with nonusers. Even though no large-scale randomized controlled trials had ever been done, doctors had "a nearly unshakable belief in the benefits of hormone therapy," wrote two doctors in a 2003 opinion piece in the New England Journal of Medicine — enough to suspend normal standards for preventive treatments, like proof from a trial.
When the first trials conducted on HRT failed to show a benefit for the heart, they were criticized and even disregarded. But when researchers finally did a big clinical study, part of the Women's Health Initiative (a large study initiated by the National Institutes of Health to look at cardiovascular disease, cancer, and other common causes of death and disability in postmenopausal women), it turned out that the estrogen-plus-progestin treatment actually increased the risk of heart attacks, strokes, blood clots, and breast cancer, while estrogen alone increased the risk of stroke and blood clots.
What's especially worrisome is that women's use of HRT "was based on much better evidence than the salt recommendation is based on, much more consistent observational studies," says Dr. Cohen. The editorial accompanying the trial, published in the same issue of the New England Journal of Medicine, stated, "The lesson is that belief, no matter how sincerely held, is no substitute for proof in the form of adequately designed randomized clinical trials when it comes to medical interventions, especially long-term interventions that are being contemplated for widespread use in order to prevent disease."
We appear not to have learned that lesson yet.
Blood Pressure by the Numbers
Systolic pressure — the first, higher number in the familiar fraction — is a measure of the peak force exerted by your blood against your artery walls when your heart pumps. Diastolic pressure — the second, lower number — measures the minimum pressure, between heartbeats. The measurement is recorded in millimeters of mercury (mm Hg), even if the cuff in your doctor's office is digital (note: recent research suggests that the old-fashioned, low-tech measuring method is more accurate).
Here is what the numbers mean:
120/80 and lower: Normal blood pressure
120 — 139/80 — 89: Pre-hypertension
140 — 159/90 — 99: Stage 1 hypertension (mild high blood pressure)
160+/100+: Stage 2 hypertension (moderate to severe)
Slashing the Salt
Food companies and restaurants add salt to their products and meals because it's a great multitasker. Flavor is a primary reason: The temperatures required to kill bacteria in processed foods often sap their taste, and salt acts as an inexpensive flavor boost. It also makes food moist, improves its texture, and prevents the growth of new bacteria. In breadmaking, salt is needed to make dough rise, and it acts as a dough conditioner, which helps a loaf hold air and stay firm.
Hypertension researchers like Dr. Hillel Cohen at Albert Einstein College of Medicine are concerned that companies participating in the National Salt Reduction Initiative might add sugar or fat to replace salt's flavor, or come up with some new substitute to preserve food and improve its texture. "Who's going to check what's being put in? Who's going to monitor those chemicals, or the sugar or the calories if they go up?" he asks. The New York City Department of Health says it will monitor these changes in the food supply, including sodium levels, sugar, and fat, but given the intense secrecy that surrounds manufacturers' recipes and formulas, it may be difficult to impossible to detect a new ingredient — or determine its effect on our health. Here are a few examples of how food producers say they are reformulating their foods to reduce the salt levels.
Ragu Old World Style Pasta Sauce
(salt added for more flavor)
Salt already reduced by 45 percent through Unilever's global sodium-reduction strategy
Added more tomatoes
Reduced corn syrup, but added regular sugar to compensate
Rebalanced herbs and spices to improve flavor
Wish-Bone Salad Dressings
(salt added as a preservative)
Reduced sodium 15 — 30 percent
Altered the sugar/acid/spice balance
Au Bon Pain Muffins
(sodium added for taste and leavening)
Currently working to reduce sodium
Experimenting with using potassium chloride (a salt substitute) or a blend of sodium and potassium chlorides
Try These Healthy Moves
Each of us can take action to manage our own blood pressure without putting the spotlight on salt. If you're not hypertensive, you don't need to obsess about sodium. Cutting back isn't going to do much for you, and will just divert your energy away from other, healthier things — like losing weight if you're overweight, or exercising. "When you get people doing stuff that they don't really need to do, they may not do the things they really should do," says Dr. Norman Hollenberg of Harvard Medical School. Instead, focus on a generally healthy diet, which includes more whole, unprocessed foods like fruits and vegetables, lean meats and fish, healthy fats like olive oil, and low-fat dairy.
If you have borderline-high or high blood pressure, work with your doctor to see if lifestyle changes, including lower sodium, can reduce it a bit. Stay away from most canned and processed foods before trying medications. Shop around the perimeter of the supermarket, where the fresh foods are usually sold. Directly or indirectly, smoking, being overweight and/or overstressed, not getting enough potassium in your diet (fruits and veggies are great sources), drinking too much alcohol, and not exercising can raise blood pressure. Recent studies have also shown that reducing sugary beverages and eating whole grains can lower blood pressure.
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