Eating too much salt is bad for your blood pressure. That’s the advice that you’ll regularly get from dietitian’s like me. However, new research out today suggests reducing the amount of salt – or specifically sodium – you eat may not be as good for your overall health as we thought.
So what exactly does the study say?
Well researchers looked at the findings from lots of previous studies (known as meta-analysis) into blood pressure. By combining the data from those studies they hoped to provide a more reliable view as to the benefits or not of reducing the amount sodium we eat.
The researchers found that when people reduce their sodium intake their blood pressure lowered, but only by 1%. They suggested that the reason the drop was so small was because the reduction in sodium triggered the liver to produce more of an enzyme called renin into the blood stream. The effect of the extra renin raised blood pressure offsetting the impact of lowering sodium.
The study also found that another of the affects of reducing sodium was to raise the level of cholesterol and triglycerides in the blood, both risk factors for heart disease. As the reduction in blood pressure was so small, and with the changes to other risk factors, the researchers concluded that lowering sodium might not be helpful to people’s overall health as previously thought.
So how reliable are the findings?
In this case the researchers carried out what’s called a meta analysis. This means they combined the data from lots of previous studies – in this study it’s 167 – into blood pressure. This allows the researchers to compensate for studies which involved only a few people, and findings which were one-offs. Meta analyses tend to produce findings that are more robust than smaller studies, or ones which are conducted in different ways.
But there were as also some important points to highlight about the findings and limitations of the study. It’s also important to note the study’s conclusions were based on white adults with normal blood pressure. For people with high blood pressure the scientists said that lowering sodium should still be a part of controlling their hypertension.
They also noted that the reduction in blood pressure from reduced sodium was larger in black and Asian populations than it was in white populations. And acknowledged that the small number of studies in black and Asian groups limited their ability to draw conclusions about the effectiveness of sodium reductions in these groups.
So what does this mean?
Well, this is just one study. Admittedly it is an important one, but recommendations that affect the whole population are only taken after looking at lots of lots of research to make sure we’re giving the best possible advice.
The researchers themselves say that further research is needed to confirm their findings and answer some of the questions it has raised.
For now, there’s no reason to change the advice that we give. We should all aim to keep an eye on the amount of salt we’re adding to our food or in the products we buy off the shelf, and make sure we don’t eat any more than about one teaspoon or 6g of salt a day.
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