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Asalting Science

BBC NEWS | Health | Cutting salt 'reduces heart risk'

Eating less salt can cut cardiovascular disease risk by a quarter and fatal heart disease by a fifth, work shows.

The ideal daily intake of salt is no more than six grams and ministers want everyone to achieve this by 2010.

Experts already know that too much salt can raise blood pressure and high blood pressure increases the risk of heart attack and stroke.

The British Medical Journal study now gives the evidence behind this link and quantifies how much harm salt can do.

People who significantly cut back on the amount of salt in their diet reduced their chances of developing cardiovascular disease by 25% over the following 10 to 15 years.

And their risk of dying from cardiovascular disease went down by 20%.

All of the 3,126 people studied by the US team from Boston had had high-normal blood pressure, or "pre-hypertension"....

Oh - so this was a study on sick people who had a particular problem that makes it more likely their ticker will go pop already. As John Brignall was saying only yesterday with regards to HRT:

There are at least two well known confounding factors to which such an observational study such as this are prey:

If the therapy is successful then the patient will have a marked change of life style.
The reasons for which the therapy was prescribed in the first place might well pose a risk factor.

So what we have here is a flim-flam study that manages to have both of these confounding factors. interestingly Professor Graham MacGregor, a consultant in cardiovascular medicine at London's St George's hospital and chairman of the Consensus Action Group on Salt, said: "This is a very important study.

"It shows that if people reduce their salt intake it will reduce the number of people suffering from heart attacks, strokes and heart failure. We did not have that type of evidence before.

I wonder if he will reissue his book now: The salt-free diet book: An appetizing way to help reduce high blood pressure. You will note he is now admitting his hugely successful campaign had "no evidence" before - and to be frank I can't see much has changed. "In our study of 3,126 one legged people we found that removing their crutches lead to them falling over more often, therefore everyone should use crutches all the time." When you consider the research that has gone into the anti-salt message then if this is the best they can do then it is pathetic. Any risk that is so hard to "prove" ain't much of a risk.

My copy of The Times this morning covers it whole front page with this scare (the online version differs) ; it reports that the conclusion is much less definite than the headlines suggest:

“Our study provides unique evidence that sodium reduction might prevent cardiovascular disease and should dispel any residual concern that sodium reduction might be harmful,” it concludes.
- the Salt Manufacturers point out "“The research only relates to subjects who already have high blood pressure. Most people have acknowledged for some time that such individuals may be advised to restrict their salt intake with their GP’s advice.

“What the evidence does not prove is that salt reduction will have any significant health benefits for the majority of us.”

Quite - I have always have a sneaking feeling that the anti-salt brigade are haunted by the idea that people might actually be enjoying their food instead of only eating through gritted teeth what is "good for them."

The two real salt health stories are the importance of iodised salt in the diet to prevent stupidity and salting your veg so kids eat more of them.

Note:
Iodine Deficiency is the primary preventable causes of mental retardation, and salt iodization is a proven cost-effective solution. Although a minute quantity of iodine ensures a person's iodine adequacy, iodine deficiency remains a major public health problems in 130 developing countries, affects over 740 million people, 13% of the world’s population.

Yet we have the means to prevent it – small quantities of iodine at low cost- through iodized salt. Salt iodization is the most logical and effective solution to IDD because it is consumed gradually, and is safe, sustainable and inexpensive (US five cents per person annually).

Comments

So, we are told, 'significantly' cutting down on salt (and thereby making food unpalatable) has a relative risk of 0.8 for death through cardiovascular disease. This is 1/1.25. RRs between 0.5 and 2 are epidemiologically worthless. Reputable scientific publications rarely accept submissions where 1/3

That should read: submissions where 1/3

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