AUSTRALIA’S failure to take appropriate action to reduce sodium consumption at a population level “is bordering on negligent”, according to a public health expert.

However, the federal government says it is already working closely with industry and public health groups to reduce the salt content of a variety of common foods.

The comments come in response to the first study in Australian adults to demonstrate a positive association between sodium intake and blood pressure, published in this week’s MJA. (1)

The researchers assessed blood pressure and 24-hour urinary sodium and potassium excretion in 783 people aged 64 years on average.

Sodium excretion and sodium-to-potassium ratio were both significantly and positively associated with systolic blood pressure after adjusting for various confounders such as age, sex, body mass index and country of birth.

Almost all the study participants consumed excessive sodium. Only six men (1.6% of all participating men) and 32 women (7.9%) adhered to Australian recommendations to consume less than 70 mmol of sodium (4 g salt) per day for chronic disease prevention.

Professor Bruce Neal, senior director at the George Institute for Global Health, told MJA InSight that the findings on salt consumption were “disappointing but not surprising”.

“It influences everyone’s health in a bad way. That’s why a salt reduction strategy has such enormous potential”, he said.

A spokeswoman for the federal Department of Health and Ageing said that the government, through the Food and Health Dialogue, had negotiated sodium reduction targets with industry for bread, breakfast cereals, processed meats and simmer sauces, with other foods planned for later inclusion. (2)

However, Professor Neal said this approach was likely to have limited impact because there were no sanctions if industry did not meet these targets. He suggested a model similar to that used in the UK, where targets were more strictly monitored and enforced under stronger leadership from government.

He said the Australian Government would have to invest $10–$20 million a year for a “gold-plated salt reduction strategy”.

“It’s a small investment for potentially enormous health gains.”

A modelling study published in the BMJ last week found that reducing dietary salt intake by 3 g a day in the UK would prevent about 4450 deaths from cardiovascular disease and save £347 million ($515 million) over 10 years. (3)

Professor Neal said although doctors could raise awareness of the link between salt intake and high blood pressure, the food environment made it difficult for most people to substantially reduce their sodium intake.

“Unless you are some sort of weirdo it’s impossible to eat a low sodium diet in Australia because salt is in everything”, he said.

If patients were adding a lot of salt to their food, then doctors could suggest practical changes such as adding less salt or using salt substitutes, he said.

In an editorial in the MJA, Professor Neal questioned why it was so hard to introduce a “plausible population-wide salt-reduction program”.

“No one is going to lose their parliamentary seat and no one is going to go out of business if they make this happen. There are just going to be a lot of unnecessary strokes and heart attacks while the people pickling us figure this out”, he wrote.

A Cochrane Review of seven clinical trials in which individual patients were advised to restrict salt intake, published earlier this year, found that reducing salt intake had no clear benefits in reducing the likelihood of dying or experiencing cardiovascular disease. Its authors said further studies were needed to determine if more effective or population-based means of salt restriction would be beneficial. (5)

However, a reanalysis of the Cochrane Review data, published in the The Lancet last week, found that its conclusions were incorrect. The reanalysis found that with a reduction in salt intake of 2.0–2.3 g per day there was a significant reduction in cardiovascular events by 20% and a non-significant reduction in all-cause mortality (5–7%). (6)

“There remains little debate about the potential for salt reduction to positively impact on human health”, Professor Neal said.

– Sophie McNamara

1. MJA 2011; 195: 128-132

2. Nutrition and Health Eating: Food and health dialogue

3. BMJ 2011; 343:d4044

4. MJA 2011; 195: 111-112

5. Cochrane Database of Systematic Reviews 2011; 7. DOI: 10.1002/14651858.CD009217

6. The Lancet 2011; 378: 380-382

Posted 1 August 2011

7 thoughts on “In a pickle over salt reduction

  1. JD says:

    It’s not as clear cut as the low-salt enthusiasts would have us believe.
    For something which should have such a dramatic effect on vascular morbidity and mortality, it has been proven difficult to show any benefit in studies, unless the data are combined in a meta-analysis. Prof Neale dismisses the JAMA study (JAMA 2011; 305: 1777-1785) which used 24h urine sodium to estimate intake because it wasn’t randomised. Yet, he needs to explain the apparent harm to high-risk patients on “low salt” diets – rather than claim it was a methodological aberration.
    It’s time for a proper large-scale RCT, using “hard” end-points (mortality and CV events) not surrogate end-points (eg, short-term change in BP).

  2. Dr Joe says:

    The Cochrane collaboration has shown that salt is not that big a deal. Lowering intake may reduce BP but does not affect mortality. The zealots are now seeking to discredit Cochrane as it dares to publish evidence which contradicts views held with religious fervor.
    The only behavior “bordering on negligence” I can see is that of public health “experts” who are all preach but no responsibility.

  3. RayT says:

    I’m perhaps fortunate to be working in a field where I don’t have to tell people what to do about their salt intake, because I’ve never been totally convinced by the “Salt is bad for you!” lobby, any more than I was by all those Cardiologists I knew back in the 1980s who wouldn’t let their wives use eggs in their cooking because of their Cholesterol content, and remarked on how good my part-French wife’s cooking was..

    I tend to disturb people by adding salt to my food, but my BP is 125/80 and I am in my late 60s.
    I suspect there are those for whom salt intake matters and those for whom it doesn’t.
    Perhaps that needs looking at.

    I’m also mindful of the suggestions that Vitamin D deficiency is becoming more common as the “Avoid the Sun!” lobby marches on.

  4. Andrew Jamieson says:

    As a 65 year old athlete with a normal BP of 100-110/60-70
    I have to add salt to my food continuously otherwise I suffer postural hypotension. Also I have had to advise post bariatric surgery patients to take salt tablets intermittently to avoid hypotension so it is important to direct anti-salt campaigns to those at risk and not everyone.
    The same applies to the strident anti-sugar campaigns – fine for the diabetics and the obese – not helpful to those needing the calories for exercise and perhaps the anti-alcohol camaigns.

  5. vicki says:

    I have been in GP for over 50 years and we seem in that time to have made no progress in the salt content in food specially in young children and snack foods. The salt content is hugs in many of these items and recently one or two low salt items have been withdrawn from the supermarket shelves. Until salt is seen across the whole community as the danger it is there seems no hope of progress.

  6. Robert Loblay says:

    The taste for salt develops early in life. Are the population health afficionados going to suggest banning the quintessential Australian yeast extract that we all grew up on? I don’t think so! I’m all for having smaller holes in the salt shakers in fast food outlets, but as for sprinkling less on my own home-cooked meals, count me out. Now that we have entered the age of nutrigenomics and personalised medicine I look forward to the day I can accurately quantify my personal genetic risk with an inexpensive home testing kit. Then I’ll decide whether I would rather forsake the salt grinder or simply take the pills and eat whatever…

  7. Jules Black says:

    What’s this – no…I don’t believe it. Salt?? How amazing!
    I graduated in 1964, and back then we were already taught about NaCl and the ætiology of hypertension.
    As an obstetrician I have always followed the principle of dietary salt restriction in pregnancy in the presence of excess weight gain. I enjoyed a very low incidence of at minimum severe hypertensive disease of pregnancy (HDP) and of lesser grades too. Only yesterday I saw a medical headline about a marked increase in stroke cases in USA in pregnancy. I haven’t seen any details yet, but I bet it is in association with HDP. Doing rural locums in four states in Australia for over 5 years now, I note a lack of appreciation of the significance of blood pressure in pregnancy among GPs and midwives alike. Like handwashing, we need to revisit tried & tested fundamentals.

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