Gary Taubes: Salt, We Misjudged You

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    Jun 05, 2012 5:34 AM GMT
    http://www.nytimes.com/2012/06/03/opinion/sunday/we-only-think-we-know-the-truth-about-salt.html?_r=1&smid=pl-share

    The idea that eating less salt can worsen health outcomes may sound bizarre, but it also has biological plausibility and is celebrating its 40th anniversary this year, too. A 1972 paper in The New England Journal of Medicine reported that the less salt people ate, the higher their levels of a substance secreted by the kidneys, called renin, which set off a physiological cascade of events that seemed to end with an increased risk of heart disease. In this scenario: eat less salt, secrete more renin, get heart disease, die prematurely.

    With nearly everyone focused on the supposed benefits of salt restriction, little research was done to look at the potential dangers. But four years ago, Italian researchers began publishing the results from a series of clinical trials, all of which reported that, among patients with heart failure, reducing salt consumption increased the risk of death.

    Those trials have been followed by a slew of studies suggesting that reducing sodium to anything like what government policy refers to as a “safe upper limit” is likely to do more harm than good. These covered some 100,000 people in more than 30 countries and showed that salt consumption is remarkably stable among populations over time. In the United States, for instance, it has remained constant for the last 50 years, despite 40 years of the eat-less-salt message. The average salt intake in these populations — what could be called the normal salt intake — was one and a half teaspoons a day, almost 50 percent above what federal agencies consider a safe upper limit for healthy Americans under 50, and more than double what the policy advises for those who aren’t so young or healthy. This consistency, between populations and over time, suggests that how much salt we eat is determined by physiological demands, not diet choices.

    One could still argue that all these people should reduce their salt intake to prevent hypertension, except for the fact that four of these studies — involving Type 1 diabetics, Type 2 diabetics, healthy Europeans and patients with chronic heart failure — reported that the people eating salt at the lower limit of normal were more likely to have heart disease than those eating smack in the middle of the normal range. Effectively what the 1972 paper would have predicted.

    Proponents of the eat-less-salt campaign tend to deal with this contradictory evidence by implying that anyone raising it is a shill for the food industry and doesn’t care about saving lives. An N.I.H. administrator told me back in 1998 that to publicly question the science on salt was to play into the hands of the industry. “As long as there are things in the media that say the salt controversy continues,” he said, “they win.”

    When several agencies, including the Department of Agriculture and the Food and Drug Administration, held a hearing last November to discuss how to go about getting Americans to eat less salt (as opposed to whether or not we should eat less salt), these proponents argued that the latest reports suggesting damage from lower-salt diets should simply be ignored. Lawrence Appel, an epidemiologist and a co-author of the DASH-Sodium trial, said “there is nothing really new.” According to the cardiologist Graham MacGregor, who has been promoting low-salt diets since the 1980s, the studies were no more than “a minor irritation that causes us a bit of aggravation.”

    This attitude that studies that go against prevailing beliefs should be ignored on the basis that, well, they go against prevailing beliefs, has been the norm for the anti-salt campaign for decades. Maybe now the prevailing beliefs should be changed. The British scientist and educator Thomas Huxley, known as Darwin’s bulldog for his advocacy of evolution, may have put it best back in 1860. “My business,” he wrote, “is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations.”
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    Jun 05, 2012 8:45 AM GMT
    People have such a fear of salt. It's a kind of orthodoxy that salt is evil.

    Yes, some people are very sensitive; most are not.
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    Jun 05, 2012 10:52 AM GMT
    Yes - along with the feeling that fat is evil. But some fats are essential while in general - it may not be that fat is bad for your health. This is not to say that they aren't but that the evidence is just not there to say they are. Or at least according to the research of Gary Taubes.
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    Jun 05, 2012 11:03 AM GMT
    Seems like they told us what we already know but nobody wants to admit: Moderation is the answer...not too much and not too little.
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    Jun 05, 2012 11:34 AM GMT
    If anything, the answer is that we don't know and I'd rather err on the side of caution.
  • jhill2456

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    Jun 05, 2012 11:42 AM GMT
    paulflexes saidSeems like they told us what we already know but nobody wants to admit: Moderation is the answer...not too much and not too little.


    What you just said. It is important to note that moderation for everyone is different. What works for me may not work for you. That is why one must work with their doctor and a nutritionist to figure out what works for them specifically. There is no easy way out when it comes to your health.
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    Jun 05, 2012 8:00 PM GMT
    Wait......what does this have to do with Obama being the spawn of Satan??? icon_confused.gif
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    Jun 05, 2012 8:07 PM GMT
    15 years ago when my dad was in the hospital getting his pacemaker installed, I was so traumatized by seeing what my dad was going through I asked his cardiologist what was the single most important thing to keep your heart healthy. He said: "go home and throw your salt shaker in the trash". I did just that and haven't used salt since. Once in a blue moon I will put a little good quality sea salt on watermelon, cantaloupe or peas but other than that I don't touch the stuff. Just had my blood pressure checked and it's fantastic.
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    Jun 05, 2012 8:48 PM GMT
    As with everything else use is usually not a problem. Abuse is.
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    Jun 05, 2012 10:59 PM GMT
    Additional article from Scientific American:
    http://www.scientificamerican.com/article.cfm?id=its-time-to-end-the-war-on-salt

    Scientific tools have become much more precise since then, but the correlation between salt intake and poor health has remained tenuous. Intersalt, a large study published in 1988, compared sodium intake with blood pressure in subjects from 52 international research centers and found no relationship between sodium intake and the prevalence of hypertension. In fact, the population that ate the most salt, about 14 grams a day, had a lower median blood pressure than the population that ate the least, about 7.2 grams a day. In 2004 the Cochrane Collaboration, an international, independent, not-for-profit health care research organization funded in part by the U.S. Department of Health and Human Services, published a review of 11 salt-reduction trials. Over the long-term, low-salt diets, compared to normal diets, decreased systolic blood pressure (the top number in the blood pressure ratio) in healthy people by 1.1 millimeters of mercury (mmHg) and diastolic blood pressure (the bottom number) by 0.6 mmHg. That is like going from 120/80 to 119/79. The review concluded that "intensive interventions, unsuited to primary care or population prevention programs, provide only minimal reductions in blood pressure during long-term trials." A 2003 Cochrane review of 57 shorter-term trials similarly concluded that "there is little evidence for long-term benefit from reducing salt intake."

    Studies that have explored the direct relationship between salt and heart disease have not fared much better. Among them, a 2006 American Journal of Medicine study compared the reported daily sodium intakes of 78 million Americans to their risk of dying from heart disease over the course of 14 years. It found that the more sodium people ate, the less likely they were to die from heart disease. And a 2007 study published in the European Journal of Epidemiology followed 1,500 older people for five years and found no association between urinary sodium levels and the risk of coronary vascular disease or death. For every study that suggests that salt is unhealthy, another does not.

    Part of the problem is that individuals vary in how they respond to salt. "It's tough to nail these associations," admits Lawrence Appel, an epidemiologist at Johns Hopkins University and the chair of the salt committee for the 2010 Dietary Guidelines for Americans. One oft-cited 1987 study published in the Journal of Chronic Diseases reported that the number of people who experience drops in blood pressure after eating high-salt diets almost equals the number who experience blood pressure spikes; many stay exactly the same. That is because "the human kidney is made, by design, to vary the accretion of salt based on the amount you take in," explains Michael Alderman, an epidemiologist at the Albert Einstein College of Medicine and former president of the International Society of Hypertension.


    Much more at the link.
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    Jun 06, 2012 12:09 AM GMT
    Can you summarize the findings for those too lazy to read the whole thing.
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    Jun 06, 2012 1:02 AM GMT
    dontknowwhy saidCan you summarize the findings for those too lazy to read the whole thing.


    The argument made is that many of us consume too little, not too much salt. That the relationship between salt and heart disease might be the inverse - that too little salt causes heart disease not too much. But this depends on what you do with your time - ie if you do more exercise, you probably need more salt than average.

    Bottomline: salt is not inherently unhealthy and you may need to consume more than you already are to stay healthy.

    [Parenthetically, I probably won't change my eating habits which doesn't include much salt beyond the odd burger I get from Burger King and bacon.]
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    Jun 06, 2012 2:04 PM GMT
    paulflexes saidSeems like they told us what we already know but nobody wants to admit: Moderation is the answer...not too much and not too little.


    Moderation in everything - including moderation.
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    Jun 06, 2012 2:05 PM GMT
    Adam228 saidIf anything, the answer is that we don't know and I'd rather err on the side of caution.


    If the answer is truly "we don't know" then there is no "side of caution". Could be that this thought of "side of caution" is actually the problem.