Hold it a minute on the salt study

saltby Alicia Nijdam

Confusion over new salt research
[Via Health News from NHS Choices]

“Salt is GOOD for you,” according to claims in the Daily Mail, which challenged conventional health advice by suggesting that “eating more could even lower the chances of heart disease”.

However, these claims are somewhat unjustified as they are based on a study that actually looked at a one-off measure of salt in people’s urine rather than in their diet. The research looked at 3,700 people’s urinary salt levels and then followed them for nearly eight years to look at their risk of high blood pressure, cardiovascular disease (CVD) and related deaths.

[More]

There are many things about this study to be concerned about. For most people in the study, their salt levels were determined by a single measure of salt in the urine – not their blood and only a single day.

They were then followed for several years. The small number of cardiovascular deaths (84) were matched with the salt levels seen on a single day up to 7 years earlier.

That is where the hype from the media comes in. The low salt group had more deaths. The high salt group has less.

But, is urinary salt levels from one day actually a useful measure of blood salt levels over a lifetime?  Could urinary salt levels have more to do with hydration or kidney function than blood salt levels? Was there any change in the urinary salt levels as time when on – perhaps those who died and started low actually went high over the time period? That it was a change in salt excretion levels that is a hallmark.

And, at best this work only applies to white Europeans and cannot be applied to anyone else.

This is an interesting result but still preliminary enough to wait for better data. But media headlines pronounce certainty that salt is good for you. No wonder people get confused.