Is too much salt really bad for your health?

By Amanda Johnson 09/05/2011

According to the Herald on Sunday this week ’Salt is not dangerous at more than a pinch’

This headline is based on a paper, published last week in the Journal of the American Medical Association (JAMA), which has been stirring up a fair bit of interest.

The research study followed 3681 participants for a mean of 7.9 years to assess whether 24-hour urinary sodium excretion predicted blood pressure and health outcomes. The authors reported that systolic blood pressure, but not diastolic pressure, changed over time and that this aligned with changes in sodium excretion. The association did not, however, translate into a higher risk of hypertension or cardiovascular disease (CVD) complications. In fact, lower sodium excretion was associated with higher CVD mortality.

So — does his mean we should all stop worrying about how much salt we eat?

In yesterday’s Herald on Sunday, Tony Astle, Masterchef guest judge and owner of Auckland’s fine dining restaurant Antoine’s, is reported as saying he had long ignored advice about salt: ’salt is flavour and your body needs it,’ he said.

And Tony Astle isn’t the only chef with this view; last year Masterchef winner Brett McGregor was reported to have said, ’Make sure you know your products – and use salt! Use more salt than you’ve ever used before.”

But what does the science really say?

Well, there is certainly good evidence from many studies that excess intake of salt is linked to high blood pressure and increased risk of cardiovascular disease.

And the JAMA paper has attracted criticism from experts in this field. For example, Professor Graham McGregor said in a Heartwire article last week that:

‘this is a ’badly written paper,” and there are “severe methodological problems” with it, most notably with urine collection in the group that had the lowest salt intake, MacGregor notes, adding that “JAMA has published a lot of controversial papers about salt. I really don’t think this is worth paying attention to. They are trying to create a stir. This is clever, but it’s harmful in my view. It’s like saying we don’t think cigarettes are harmful so we shouldn’t do anything about smoking,” he adds.

“The overall evidence [in favor of salt reduction] is overwhelming,” MacGregor asserts. “That isn’t to say we wouldn’t change our mind if we had really good evidence, but I don’t think this is it. This will not divert us from reducing salt intake worldwide. At a high-level meeting of the World Health Organization, salt reduction has been recommended as the next thing after tobacco reduction because it’s so cost-effective to implement and so easy to do.’

Yes, salt does provide flavour and we do need it — but too much is not good for our health. As the Herald on Sunday article goes on to report, current intakes of salt are much higher than we actually need and there is some sensible advice from Delvina Gorton from the New Zealand Heart Foundation to cut down on processed foods with a high salt content. For more information and advice from the NZHF, check out their fact sheet on salt.

Although salt does add flavour to food, so do many other ingredients. Have a look at this Heart Foundation fact sheet on alternative flavouring suggestions.

The latest nutritional recommendations for New Zealand advise us to aim to reduce our intake of salt to 4g per day — this is significantly below the 9g a day that we are currently, on average, consuming.

There is certainly plenty of confusion about salt and sodium in New Zealand. A consumer survey commissioned by NZFSA published by MAF earlier this year found that there was a lack of clear understanding of the relationship between sodium and salt, with only 36% of those surveyed correctly determining that salt contains sodium. Almost as many (32%) thought salt and sodium are exactly the same, while a quarter did not know, and 6% thought sodium contained salt.

So, overall, I don’t think the JAMA study provides us with evidence to start pouring the salt over our food. And amid the current confusion around salt and sodium, for those who have high blood pressure, the standard advice still applies: keep to a healthy weight, avoid too much alcohol, and keep the salt intake to a minimum. There is also good evidence from the DASH (dietary approaches to stop hypertension) trials that in addition to having a low salt (or low sodium) diet, there are additional benefits to having a diet rich in potassium, calcium and magnesium – with fruits, vegetables, and low-fat dairy, along with whole grains.

The HEARTsafe programme , facilitated by the New Zealand Heart Foundation, is certainly a positive initiative as well. This initiative aims to reduce the sodium content of manufactured foods and involves food manufacturers, food industry associations, and health and nutrition experts. Given that three quarters of our salt intake comes from manufactured foods this is certainly a programme that we should all welcome.