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Open Season on Salt: What the Science on Hypertension Really Shows
Scientific American ^ | September 26, 2012 | Melinda Wenner Moyer

Posted on 09/27/2012 11:15:25 PM PDT by neverdem

Shedding pounds may be a better way to promote cardiovascular health than avoiding the saltshaker

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.

What about the implication that kids would be better off if they simply cut back on their salt intake? Governmental organizations including the CDC and IOM advocate for population-wide salt reduction, but some researchers question the science behind these policies. "Cutting back on salt does reduce blood pressure, but it may not reduce the risk of dying early," explains Katarzyna Stolarz-Skrzypek, a cardiologist at Jagiellonian University Medical College in Poland.

In a 2011 study published in JAMA The Journal of the American Medical Association, Stolarz-Skrzypek and her colleagues compared the urinary sodium levels of 3,681 people with their risk of dying over the course of eight years. They found, surprisingly, that the more sodium their subjects ate, the less likely they were to die. In particular, the death rate among those eating the least sodium was 4.1 percent, but it was only 0.8 percent among avid salt consumers.

One factor behind this strange trend is that low-salt diets do more than just lower blood pressure. "Cutting sodium can cause other physiological changes such as increased resistance to insulin, which can set the stage for diabetes and increase the risk of death from heart disease," Stolarz-Skrzypek says. "Too little sodium can also increase sympathetic nerve activity, which raises the risk of heart attacks, and boost the secretion of aldosterone, a hormone produced by the adrenal gland that is bad for the cardiovascular system." A 2011 review published by the Cochrane Collaboration, an international, independent, not-for-profit research organization funded in part by the World Health Organization, concluded that low-salt diets are associated with "increases in some hormones and lipids, which could be harmful if persistent over time."

Looked at another way, the CDC study suggests that parents of overweight and obese kids should focus on weight loss, not salt reduction. Multiple studies in both adults and children suggest that weight has a bigger effect on blood pressure than salt does, and once kids reach a healthy weight, eating too much salt may not cause problems. Plus, going from obese to an appropriate weight reduces not only blood pressure but also the risk for conditions such as cancer, depression and type 2 diabetes. Shedding pounds isn't easy, but considering that an estimated 75 percent of our sodium intake comes from store-bought processed foods rather than what is added during cooking or at the dinner table, cutting back on salt isn't either—and ultimately, doing so may not be as beneficial for us as we think it is.


TOPICS: Culture/Society; Government; News/Current Events; Testing
KEYWORDS: diabetes; hypertension; salt; type2diabetes
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To: neverdem

bttt


41 posted on 09/28/2012 5:26:01 AM PDT by Scotswife
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To: tnlibertarian

Strangely believe it, when I resumed eating butter and bacon and such, my numbers improved. There might be something to what you say.

Growing older though seems to be a major factor in friction increase.


42 posted on 09/28/2012 5:37:07 AM PDT by bert ((K.E. N.P. N.C. +12 ..... Present failure and impending death yield irrational action))
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To: HangThemHigh
So if I eat some of the Earth Mother's poison ivy, that will be good for me too? After all, it's natural.

What asinine response. Please go take a few reading comprehension courses.

43 posted on 09/28/2012 5:40:58 AM PDT by MrDem (Founder: Democrats for Cheney/Palin 2012)
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To: ConservativeDude
a history through salt, it was pointed out that in previous eras, Europeans and Americans ate FAR more salt than nowadays.

It was not today's processed salt that has all of the minerals stripped out of it.

44 posted on 09/28/2012 5:43:40 AM PDT by MrDem (Founder: Democrats for Cheney/Palin 2012)
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To: bert

Bacon and butter are okay per Atkin’s, right? Did you cut out any carbs at the same time? Since being diagnosed with Type 1 diabetes last year, I have been working on changing my diet, but there is just an overload of information, much of it conflicting. I’ve done pretty good by lowering my carb intake, particularly bread at night. Alas, I believe I may have had my last piece of pizza.


45 posted on 09/28/2012 5:46:25 AM PDT by tnlibertarian (Government's solution to everything: Less freedom.)
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To: tnlibertarian

yes..... decrease in carbs has made a big difference. I’m type 2 diabetic.

Decreasing carbs + exercise has produced weight loss that lowered Body Mass Index that is <30 and I feel much better. My WII chides me to set a goal of 22...... tough goal.

The nightly heart burn from carbs is also dissipated/gone.

Re: information..... there is a lot.

I took part in a diabetic drug trial with intensive attention. I went every week to report my daily blood sugar readings and have blood drawn. That process made me aware of the effect of carbs on both a macro and a micro level. It was very interesting and informative. I will never know if I had the drug or a placebo, but I had three months of fantastic free health care.


46 posted on 09/28/2012 5:59:46 AM PDT by bert ((K.E. N.P. N.C. +12 ..... Present failure and impending death yield irrational action))
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To: Lancey Howard

I am 71 have always used salt LIBERLEY. BP 110/59. No health problems other than Idiopathic Pulmonary Fibrosis which has nothing to do with diet or blood pressure.


47 posted on 09/28/2012 6:51:09 AM PDT by Coldwater Creek (He who dwells in the shelter of the Most High will rest in the shadows of the Almighty Psalm 91:)
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To: MrDem

Yes, there is a lot of evidence that what we have done to wheat has made it worse for us.


48 posted on 09/28/2012 8:44:42 AM PDT by Yaelle
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To: neverdem

I have eaten loads of salt all of my life and my BP has always been on the low side. So low it was almost undetectable in my teens and 20s.


49 posted on 09/28/2012 10:34:16 AM PDT by TigersEye (dishonorabledisclosure.com - OPSEC (give them support))
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To: BuffaloJack; bert; tnlibertarian

Look up “negative feedback loop” or “negative feedback inhibition.” I can’t think of a hormone that doesn’t behave according to it.

Type 1 diabetics have lost it regarding insulin and glucose homeostasis. They require exogenous insulin.

Insulin resistance in type 2 diabetics requires more endogenous insulin or insulin sensitizing drugs for glucose homeostasis. They can get worse to the point where they require exogenous insulin.


50 posted on 09/28/2012 11:34:03 AM PDT by neverdem ( Xin loi min oi)
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To: neverdem

Politics drives science. Who pays the scientist calls the conclusion.


51 posted on 09/29/2012 2:33:11 AM PDT by 1010RD (First, Do No Harm)
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To: neverdem

I’ve read that the majority of Americans (meaning more than 60%) are deficient in potassium and magnesium. Both of which have been shown to normalize blood pressure.

It’s junk science to take a population that already are malnourished, feed them an excess of sodium, and then blame the results on the salt.


52 posted on 09/29/2012 2:45:57 AM PDT by djf (Political Science: Conservatives = govern-ment. Liberals = givin-me-it.)
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