A Taste of Wellness for Savoury and Snacks
Givaudan
The new study, published in the Journal of the American Medical Association (JAMA), examined health outcomes related to salt intake, including the incidence of death, illness and hypertension in relation to measures of urinary sodium excretion.
The research reported that lower sodium excretion was associated with an increased risk of cardiovascular death, while higher sodium excretion did not correspond with increased risk of hypertension or cardiovascular disease complications.
Speaking to FoodNavigator on behalf of Consensus Action on Salt and Health (CASH), Professor Graham MacGregor said that the observational study “is extremely paradoxical, suggesting that salt puts up blood pressure yet relates inversely to cardiovascular events – even though it is known that raised blood pressure is the biggest risk factor for cardiovascular disease, accounting for approximately 62 per cent of strokes and 49 per cent of all heart disease.”
“The associations between systolic pressure and sodium excretion did not translate into less morbidity or improved survival … On the contrary, low sodium excretion predicted higher cardiovascular mortality,” said the researchers, led by Dr Katarzyna Stolarz-Skrzypek of the University of Leuven, Belgium.
“Taken together, our current findings refute the estimates of computer models of lives saved and health care costs reduced with lower salt intake … They do also not support the current recommendations of a generalized and indiscriminate reduction of salt intake at the population level,” they added.
Controversy
The new JAMA study has already come in for some criticism. Prof MacGregor, of the Wolfson Institute of Preventive Medicine, and chairman of CASH explained that the paper has “what appear to be severe methodological problems”, adding that “it is difficult to critically assess this paper.”
In addition, officials at the Centers for Disease Control and Prevention (CDC) felt so strongly that the study was flawed that they criticized it in an interview with the New York Times – something they normally do not do.
Dr. Peter Briss, medical director at the CDC, told the NY Times that it is hard to draw any conclusions from the study given its relatively small size, and use of relatively young participants.
MacGregor and Briss both highlighted that the study goes against a raft of evidence showing that salt reduction is beneficial to the general population.
“This paper does not provide any substantiated evidence to the contrary,” said MacGregor, whilst Briss added that the study “might need to be taken with a grain of salt.”
“There is no evidence that a modest reduction in population salt intake has any harmful effects on health, as such salt reduction is the simplest and most cost-effective method of reducing cardiovascular disease next to tobacco reduction,” added MacGregor.
Study details
The researchers’ studied data from a prospective population study, involving 3681 participants without cardiovascular disease (CVD).
Among the 3681 participants followed, CVD deaths decreased with increasing measures of 24-hour sodium excretion, from 50 deaths in the lowest group, to 24 for medium excretion, and 10 in the highest excretion group.
“Lower sodium excretion was associated with higher CVD mortality,” said Dr Stolarz-Skrzypek and colleagues; noting that this inverse association between sodium excretion levels and death from CVD was statistically significant.
The researchers added that systolic blood pressure, but not diastolic pressure, changes over time aligned with changes in sodium excretion, “but this association did not translate into a higher risk of hypertension or CVD complications.”
“It is unlikely that these findings were due to reverse causality because we excluded patients with a history of CVD … Moreover, these observations were consistent when we censored cardiovascular deaths over a time span ranging from 6 to 21 years, or excluded cardiovascular deaths occurring within 3 years of enrolment,” they explained.
Source: Journal of the American Medical Association (JAMA)
Volume 305, Issue 17, Pages 1777-1785, doi:10.1001/jama.2011.574
“Fatal and Nonfatal Outcomes, Incidence of Hypertension, and Blood Pressure Changes in Relation to Urinary Sodium Excretion”
Authors: K. Stolarz-Skrzypek, T. Kuznetsova, L. Thijs, V. Tikhonoff, et al
5 comments (Comments are now closed)
What about sodium intake?
Did the researchers measure sodium intake?
Maybe the fact that people in the low risk group excreted more sodium is the key. If everyone ate the same amount of salt, those who excreted more would naturally be at a lower risk for hypertension and heart disease.
Report abuse
Posted by Kay
11 May 2011 | 16h12
Salt reduction case unproven
To convince me that salt is the main culprit in cardiovascular disease and hypertension you would have to show that vegans consuming a high salt diet will develop cardiovascular problems/hypertension compared to a low salt diet. Such a study has not been done, but is necessary so as to remove all the confounders, fat, cholesterol, high purine intake, too much protein. In addition, a plausible explanation is needed as to why the traditional Mediterranean diet, despite the high consumption of olives loaded with brine, and yet have relatively low blood pressure and cardiovascular disease in general.
Report abuse
Posted by Tony
04 May 2011 | 23h22
New Study
With good reason Morton posted this comment. He belongs to the North American-based non-profit salt industry trade association.
Report abuse
Posted by John
04 May 2011 | 22h55
Salt Intake
Why do you classify them as fanatics? The truth in this matter is that "1 in 3 people in America face hypertension or high blood pressure. Uncorrected hypertension can lead to chronic renal failure, congestive heart failure, heart attack, stroke, and arterial aneurysm. Sure there are other factors affecting these health issues but the number one factor is a diet high in sodium and low in potassium or Vitamin D. It is a proven fact. The problem we face is that almost all processed foods have too much sodium content. We should eat more fresh, less processed, and less sodium-laden foods. The problem is not that we add salt to our food at the dinner table. The problem is that most foods that we eat already have too much sodium. The body actually only requires 500 mg of sodium per day. Studies show that more than 2300 mg of sodium intake daily is associated with high blood pressure(its risks) and edema. Yes we do need a good balance of sodium and potassium but not excess sodium. We should increase our potassium by eating more leafy green vegetables, root vegetables and fruits from the vine. Eat unprocessed foods and add spices and herbs as seasonings. This should be our goal. Your comment about salt reduction actually causing overall health to worsen is absurd.
Report abuse
Posted by John
04 May 2011 | 17h04
New study consistent with previous work
The strident criticism of this new paper by the anti-salt activists reflects their fear of any data that might counter their agenda. These fanatics have tied their careers to salt reduction and regard the public as if they were lab rats and are quite willing to place them into a massive trial on dietary salt reduction without their knowledge or consent. Of course, these activists try to belittle every piece of scientific evidence that challenge their opinions. They have vested heavily into the urban myth of salt reduction and will reject any scientific evidence that might contradict it. They will have to be busy in future, because their doctrine will not trump science. The evidence debunking the benefits of salt reduction will continue to pour in simply because human physiology answers to a far higher authority than these salt reduction activists.
Reducing blood pressure is good, particularly for people with hypertension, but what matters is the way in which you accomplish this. If you eat a Mediterranean or DASH-type diet, or if you get into better physical shape, you reduce blood pressure without any negative health consequences. On the other hand, if you reduce your salt consumption, your body’s hormonal system swings into high gear to compensate for it. The elevated levels of renin and aldosterone that develop the minute you cut back on salt will cause a cascade of negative cardiovascular and diabetic consequences. So all you end up doing is robbing Peter to pay Paul – you trade off one risk factor (blood pressure) for an even greater one (elevated renin-aldosterone) which is why so many on low salt regimes have greater morbidity and mortality. And it’s elevated renin-aldosterone levels that the anti-salt activists always try to conceal. Using salt reduction as a strategy to reduce blood pressure is no better than the old practice of blood-letting. Your pressure may drop, but your overall health result will be far worse.
Report abuse
Posted by Morton Satin
04 May 2011 | 15h11
Read all comments (5)