The latest news reports about salt are enough to make a parent ponder a household ban on pizza and cold cuts. A study published last week in Pediatrics found that children eat, on average, 3.4 grams of sodium daily—more than twice the amount recommended for adults by the Institute of Medicine (IOM). News outlets, including the Associated Press and USA Today, explained that, according to the study, the quarter of American kids who eat the most sodium are twice to three times as likely to develop high blood pressure as the quarter who eat the least. The take-home message from these stories is clear: kids need to cut down on salt or they will suffer serious health consequences.

It's a compelling argument. Problem is, it may be wrong.

The study that these articles reference, which was published by researchers at the U.S. Centers for Disease Control and Prevention (CDC), did not actually find a statistically significant association between salt intake and blood pressure in kids. And the doubling or tripling of risk described by some outlets isn't an accurate portrayal of the findings either. As lead author Quanhe Yang explained to Scientific American in an interview, high salt intake doubles the odds that kids have hypertension or pre-hypertension (and again, this doubling is not statistically significant), but odds and risk are two very different things. "I am not sure the best way to convert this odds ratio into a risk ratio," Yang says, but if he had to guess, the risk would probably be lower than the odds.

Yang's study does provide compelling insights. It shows that among obese or overweight children, increased salt intake is linked to higher blood pressure, an association that is statistically significant. Scientists have long known that obesity increases hypertension risk in adults and kids, but the CDC's study suggests that being overweight might also make kids more sensitive to salt's blood-pressure-boosting effect.

Still, the kids' blood pressure changes were not huge: The overweight children who ate the most sodium—an average of about 4.6 grams per day—had an average systolic blood pressure (the top number in the blood pressure ratio) of 112.8 millimeters of mercury (mmHg), whereas those who consumed the least—an average of 2.3 grams of sodium—had an average systolic pressure of 109 mmHg. (The two groups’ average diastolic pressures, the bottom number in the ratio, were the same.) In other words, among overweight and obese kids, a doubling of sodium intake was associated with a 3 percent increase in systolic blood pressure. This difference may not be clinically significant for individuals, because "systolic blood pressure changes from minute to minute" by as much as 5 mmHg, says Michael Alderman, a professor emeritus at Albert Einstein College of Medicine and editor in chief of the American Journal of Hypertension.

An average systolic blood-pressure difference of 3 percent could, however, have consequences for overall public health. But Yang says that it's impossible to tell from his study whether eating more salt actually causes blood pressure to rise. "This is a cross-sectional study; we cannot say anything about causality," he explains. Although he and his colleagues tried to control for potentially confounding variables, it's possible that kids who eat more salt also have other habits that predispose them to high blood pressure. (For instance, research suggests that children who eat lots of salt also drink lots of soft drinks, which are associated with blood pressure increases, too.) Indeed, research doesn't always support the notion that salt causes high blood pressure: A large, multicenter study known as INTERSALT compared urinary sodium levels—an accurate indicator of prior sodium consumption—with hypertension in more than 10,000 people in 1988 and found no statistically significant association between them. In fact, the population that ate the most sodium had a lower median blood pressure than the population that ate the least.

11 Comments

1. 1. SteveinOG 10:29 AM 9/26/12

   I'm amazed that this article does not mention sodium/potasium balance in the diet.

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2. 2. Ralf123 03:59 PM 9/26/12

   I was right at the limit in my last checkup (130 systolic) although I live extremely healthy, so I went through the pain of adding up all the milligrams of sodium from my usual diet. It's amazing how it adds up even from healthy foods. Now I rinse beans and tuna and try to get as much potassium in as possible. Thank goodness I like bananas, tomatoes and spinach.

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3. 3. ironjustice 10:10 AM 9/27/12

   One curious thing is in the salt sensitive Dahl mouse they have shown by restricting iron , the salt sensitivity goes down.
   "Dietary Iron Restriction Prevents Hypertensive Cardiovascular Remodeling in Dahl Salt-Sensitive Rats"
   Adding salt to your meat causes and increased release of iron.
   "Cooking and addition of NaCl caused increase in measured nonheme iron content and had a synergistic effect on the release of nonheme iron in meat"

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4. 4. RockyBob 10:11 PM 10/1/12

   There it is: "...INTERSALT compared urinary sodium levels—an accurate indicator of prior sodium consumption—with hypertension in more than 10,000 people in 1988 and found no statistically significant association between them. In fact, the population that ate the most sodium had a lower median blood pressure than the population that ate the least."
   
   Forget about highly inaccurate "self reported salt intake", here is a methodology that can determine objectively salt intake and compare it to blood pressure. And guess what -- no correlation with a sample size of ten thousand!! Any further discussion/ hypothesis of the dangers of salt intake better be able to explain away this study. I'm betting there is no viable explanation, and that salt ingestion is harmless.

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5. 5. Piume 01:33 AM 10/2/12

   Salt is a mean of NA+ in take to the body. Na+, K+, Cl-,P+3, ions are very much important to Neurons actions in the brain. Also Pituitary gland where's the leader to the Hormonal activity stimulated by the Neurons in the brain.
   While imbalance of these ions are not found with a imbalance diet.What I found in Sri Lanka almost every food menu contain bit of salt.In Amarican food they are not using salt in almost every food.
   Hypertension might not only buy food salt its occurs by the stress as what I feel.

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6. 6. lwcurtis 03:47 PM 10/2/12

   I eat healthy. I sweat a good deal. I drink 9+ pints of water each day. I have to salt my food plus drink electrolyte drinks in order to not go fuzzy from sodium and potassium deficiency.

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7. 7. rgcorrgk 07:08 PM 10/2/12

   When we get 180 news like this it tends to discredit health advice across the board, it weakens all areas of health education. When it is difficult for health professionals to sort it out, it's near hopeless for average Jo.
   Some time back there was a report of large areas of retardation in China linked to salt (no Iodine in the salt thought the problem). The iron connection (mention above in comment ironjustice) is especially interesting given iron is added ubiquitously, as a health positive, to so many foods – children’s cereal etc... It would seem even at this late date there is much to learn about a very basic substance.
   
   Richard Carlson

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8. 8. RockyBob 08:42 PM 10/2/12

   To rgcorrgk. You are right on, only it is a much bigger problem than you may imagine. I've been researching diet and nutrition studies fairly vigorously since I retired six plus years ago. I'd always assumed that "medical scientific research" was as scientific as other, hard, sciences. Way wrong. The core problem is the absolute refusal of the medical scientist community to "punish" terrible research and researchers. Everybody is too busy doing their own thing to properly attack and drive out incompetent or duplicitous or money-driven articles. What a crime that your physician and mine have to disregard virtually all articles because they cannot trust traditional sources. Major medical schools (I'm talking to you, Harvard) should lead the way in assuring that anything published and referring to that school is of the highest caliber. Shame on all of them for failing so completely.

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9. 9. RockyBob 08:42 PM 10/2/12

   To rgcorrgk. You are right on, only it is a much bigger problem than you may imagine. I've been researching diet and nutrition studies fairly vigorously since I retired six plus years ago. I'd always assumed that "medical scientific research" was as scientific as other, hard, sciences. Way wrong. The core problem is the absolute refusal of the medical scientist community to "punish" terrible research and researchers. Everybody is too busy doing their own thing to properly attack and drive out incompetent or duplicitous or money-driven articles. What a crime that your physician and mine have to disregard virtually all articles because they cannot trust traditional sources. Major medical schools (I'm talking to you, Harvard) should lead the way in assuring that anything published and referring to that school is of the highest caliber. Shame on all of them for failing so completely.

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10. 10. Ed Rybicki 04:05 AM 10/3/12

    Finally, something to wave at my in-laws when they glare at me when I reach for the salt cellar...B-)

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11. 11. sunnystrobe 09:31 AM 10/3/12

    To SteveinOG
    This article is lopsided indeed, and the essential sodium/potassium balance is inexcusable I think. But one-sided medical studies like this are par for the course, because they tend to treat only ONE food element in total isolation, doing an injustice to the body condition IN VIVO, which is always about synergies .
    I come from a meat- and sausage-eating Bavarian background, but have since down-tuned my salt intake enormously by evolving more and more into a 'saladonian'
    and have felt much better healthwise since.
    I can only explain this with the help of evolutionary anthropology; after all, we are by body design classy 'chimps de luxe'! And being in that class, we would have got our sodium as well as our potassium/etc. intake from
    plant sources, in a body-friendly, chelated form.
    Think: greens, with their unique, solar power protein that is built into their chlorophyll molecules, together with many other goodies, e.g. magnesium.
    Added salt stresses the kidneys, which have too tiny capillaries to cope in the long run with the added pressure from flushing out 9 parts of water for every 1 part of sodium chloride. High salt consumption is linked statistically with high cancer rates, too.
    A recent Harvard study found that meat eating is life-shortening. Meat would be totally inpalatable without salt. And so would bread, and refined carbs like pasta and bread! This is due to the salt lick reflex, which makes us automatically salivate, to cope with the elimination of this de-hydrating, addictive substance.
    Youthevity.com
    

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