Friday, July 12, 2013
CDC admits long-standing error, there is no benefit in reducing salt
Theory proven wrong by multiple facts. I have been saying this for years -- JR
A recent report commissioned by the Center for Disease Control (CDC) reviewed the health benefits of reducing salt intake and the take-home message is that salt, in the quantities consumed by most Americans, is no longer considered a substantial health hazard.
What the CDC study reported explicitly is that there is no benefit, and may be a danger, from reducing our salt intake below 1 tsp per day. What was absent about the report was is the difference between healthy mineral salts and iodized table salt.
It may be that we’re better off with more salt than less, up to 2 or even 3 tsp per day. How did it happen that such standard medical advice drifted astray, then went un-corrected for so long?
This review by the National Academies Institute of Medicine (IOM), commissioned by CDC, considered dozens of studies, from cross-cultural (less reliable) to prospective, randomized with control (most reliable). Most studies showed no relationship between salt intake and any health outcome. Some seemed to indicate that more salt had a beneficial effect.
One 2008 study the committee examined, for example, randomly assigned 232 Italian patients with aggressively treated moderate to severe congestive heart failure to consume either 2,760 or 1,840 milligrams of sodium a day, but otherwise to consume the same diet. Those consuming the lower level of sodium had more than three times the number of hospital readmissions — 30 as compared with 9 in the higher-salt group — and more than twice as many deaths — 15 as compared with 6 in the higher-salt group.
Another study, published in 2011, followed 28,800 subjects with high blood pressure ages 55 and older for 4.7 years and analyzed their sodium consumption by urinalysis. The researchers reported that the risks of heart attacks, strokes, congestive heart failure and death from heart disease increased significantly for those consuming more than 7,000 milligrams of sodium a day and for those consuming fewer than 3,000 milligrams of sodium a day.
To translate this last study into teaspoons: the finding was that anything between 1-1/2 and 3 tsp of salt per day is just fine, and there were adverse effects from eating more than that or less than that. Most Americans who are not consciously restricting salt fall in this range (1-1/2 to 3 tsp).
People who are on low-salt diets for medical reasons are getting as little as 1/2 tsp, and they’re well into the range where dearth of salt is harming them. The worst impact of low salt is on insulin sensitivity. Loss of insulin sensitivity is a big risk factor for all the diseases of old age.
Salt is the most common and readily available nonmetallic mineral in the world. So how could a mineral which we’ve bathed in and absorbed in all foods since our existence be so harmful for the human body? Two words. It isn’t. Actually, the opposite is true. A low salt diet will actually increase your risk of death.
World renowned salt researcher Dr. Brownstein states that even in those individuals with high blood pressure, the lowering effect is quite modest at best when reducing salt. Many researchers imply that any effect on blood pressure is not a direct consequence of salt at but other minerals acting on the body. Still, Dr. Brownstein will tell you that he learned in medical school the traditional party line that salt = hypertension (high blood pressure). A myth of mammoth proportions.
A study by lead researcher Dr. Niels Graudal, of Copenhagen University Hospital in Denmark, adds to a growing body of research questioning the long-term benefits of a low-salt diet. A review of seven previous studies published in the journal the Cochrane Library found that a moderate reduction in salt intake did not reduce a person’s risk of dying or having heart disease.
In a systematic review published by The Cochrane Library, British scientists found that cutting salt consumption did not translate into lower death or heart disease risk. “With governments setting ever lower targets for salt intake and food manufacturers working to remove it from their products, it’s really important that we do some large research trials to get a full understanding of the benefits and risks of reducing salt intake,” said Rod Taylor of Exeter University, who led the review.
WHY have we been told that salt is so deadly? It has what nutritionists like to call “biological plausibility.” Eat more salt and your body retains water to maintain a stable concentration of sodium in your blood. This is why eating salty food tends to make us thirsty: we drink more; we retain water. The result can be a temporary increase in blood pressure, which will persist until our kidneys eliminate both salt and water.
The scientific question is whether this temporary phenomenon translates to chronic problems: if we eat too much salt for years, does it raise our blood pressure, cause hypertension, then strokes, and then kill us prematurely? The answer is no.
A paper published in the American Journal of Hypertension warns that once average daily consumption dips to below 6.25g, the risk of heart attacks and strokes starts to increase once more.
Restricting salt consumption increases levels of cholesterol and triglycerides — both of them harmful fats which cause heart disease — and also leads to insulin resistance (the early stages of type-2 diabetes). Diets low in salt also increase the levels of fat and hormones in the blood that are known to increase the risk of heart disease.
Iodine: The IQ mineral
Table salt is normally iodized and that should be the end of any problems. Enter the "war on salt", however, and iodine deficiency may build up -- and dire health outcomes may result
Unless you were a regular at the sushi bar or ate fish twice a week it used to be hard to get enough iodine in your diet – but there are signs that putting iodised salt in our bread has made this easier. Nearly four years ago concerns about iodine deficiency led to bread being fortified with iodised salt. Measures of iodine concentrations in the urine of school children in Tasmania show that iodine intake is higher now than before fortification began.
But we’re not out of the woods yet – there are also signs that pregnant women may not get enough iodine to ensure the optimal brain development of their unborn babies, says Associate Professor Karen Charlton of Wollongong University’s School of Health Sciences. Research by Charlton and her team suggests that many pregnant women may be low in this mineral which is essential for an unborn baby’s developing brain.
While adults need 150 mcg of iodine daily, the need for this mineral jumps by 50 per cent during pregnancy and breastfeeding - and that’s more than a few slices of bread with iodised salt can deliver. But although the National Health and Medical Research Council recommends iodine supplements for women who are pregnant or planning to be, Charlton says the message isn’t loud enough.
“In surveys we’ve done in the Illawarra region, about 40 per cent of women attending public antenatal clinics said they don’t take iodine supplements. Women aren’t aware how important iodine is in pregnancy and my feeling is that many women aren’t given advice to take a supplement," says Charlton. “But new research has linked a low iodine intake in pregnancy with a reduced IQ in children.”
One UK study published in the medical journal The Lancet in May, reported that children of women with a mild to moderate iodine deficiency in pregnancy had lower scores for verbal IQ, reading accuracy and reading comprehension, compared to children born to women with adequate iodine intakes. A study from Tasmania’s Menzies Research Institute has also attributed better scores on the NAPLAN school test in nine-year-olds to differences in iodine intakes of their mothers in pregnancy.
“There are many factors affecting a child’s intellectual development, including childhood experiences and the parents’ education level – but these studies controlled for other factors and still found an impressive association with iodine intake in pregnancy,” Charlton says.
Most adults should be able to get enough iodine with three slices of bread (unless it’s organic bread which isn’t required to have iodised salt) and two to three serves of dairy food daily, a couple of serves of fish or seafood weekly and sushi now and again, Charlton says. But this may not be enough for pregnant women – especially those who don’t eat much bread or are wary of eating fish in pregnancy.
How did we get to be low on iodine to begin with? There are a few reasons - low iodine levels in soil, less use of iodine-based cleaning products in the dairy industry which once boosted the iodine content of our dairy food, the fact that we now eat so much processed food which uses non-iodised salt and that we tend to use non-iodised salt at home.
If you’re pregnant or breastfeeding Karen Charlton suggests a multivitamin containing 150mcg of iodine – although women with a thyroid problem should talk to their doctor because too much iodine can exacerbate some thyroid conditions.
Can a healthier iodine intake in childhood make up for a shortfall in the womb?
“No - most brain development occurs during pregnancy,” explains Professor Cres Eastman, Asia Pacific regional co-ordinator for the International Council for Control of Iodine Deficiency Disorders. “But an adequate iodine intake is still important in childhood and children who don’t drink milk or eat bread – foods that are often the main source of iodine in childhood – need a daily supplement of 100mcg of iodine.”
Posted by jonjayray at 12:25 AM