Major new studies show huge benefits of eating less salt
Two evidence reviews clearly demonstrate that a stricter salt reduction strategy would lower blood pressure and prevent heart attacks, strokes and other diseases
Two major new studies have clearly demonstrated that eating less salt lowers blood pressure and therefore prevents diseases of the heart and blood vessels - such as heart attacks and strokes – and other serious illnesses. They add irrefutable evidence to the already-strong argument for the food industry to add less salt to their food products, and as we are still eating too much salt, for the government to take stronger action to enforce such a strategy.
A systematic review shows salt reduction lowers blood pressure
The first of the studies was a systematic review and meta-analysis of trials looking at salt reduction and how it affects blood pressure. This is the most reliable type of research study as it collects together all the good-quality trials to date on this topic.
The review included 133 trials and 12,197 people looking at eating less salt compared to usual or higher salt intakes. The results clearly showed that eating less salt lowers blood pressure and there was a dose response effect – meaning the less salt, the better.
This effect was seen in people with healthy blood pressure and, encouragingly, had even greater effect in people who are older, have higher blood pressure, or are of non-white ethnicity – this is important as some groups including people from African Caribbean and Asian backgrounds tend to have higher blood pressure and higher risk of related disease.
The review was published in February in the respected journal, the BMJ (British Medical Journal), by a team of international researchers including our Chairman and Professor of cardiovascular medicine, Graham MacGregor, and friend of Blood Pressure UK, Feng He, Professor of global health research.
Read the full paper in the BMJ.
State-of-the-art review shows eating less salt can prevent numerous diseases
The second study is the most comprehensive review to date of all types of research looking into salt and health. It included almost 200 studies and explored how salt puts up blood pressure and leads to diseases of the heart and blood vessels. They also looked at the other ways salt is damaging for health, leading to conditions such as kidney disease, stomach cancer, osteoporosis, dementia and obesity.
The evidence showed that high salt intake is a direct cause of high blood pressure, and the mechanisms are interconnected with the other diseases associated with a high salt intake. They include effects on fluid balance, hormones, inflammation, the immune response, gut microbiome and damage to small vessels. They even found that salt reduction reduces diseases of the heart and blood vessels in ways other than through blood pressure.
The highlights noted by the authors included:
- Our high salt intake is among the top three dietary risk factors for disease worldwide.
- Population-wide reduction in salt intake lowers blood pressure and reduces the number of people with diseases of the heart and blood vessels and other chronic (long-term) diseases.
- The findings from flawed studies that contradict this do not refute this evidence.
- Salt-reduction efforts should be reinforced worldwide to save millions of people dying unnecessarily from stroke and heart disease each year.
Take a look at this useful illustration of how salt affects the body in interconnected ways.
The team also included Professor He and Professor MacGregor and the research was published in the JACC (Journal of the American College of Cardiology) in February. They state that salt reduction programs are cost-effective and should be put in place or sped up in all countries worldwide.
Why these studies matter
In the UK we are currently eating well over the recommended limit of 6g per day. These studies represent the huge body of research showing that too much salt raises blood pressure causing strokes and heart attacks, and leads to osteoporosis, stomach cancer, kidney disease and dementia. Eating less salt has the opposite effect, protecting health.
Unfortunately, it is very difficult to know how much salt you are eating because most salt is hidden in everyday foods such as bread, cheese, ham and sauces. While people can take steps to reduce their own salt intake such as choosing healthier products and adding less salt at home, most salt we eat comes from ready-made foods. The current research puts forward a strong case for legislation from the government for food manufacturers to add less salt to the foods they produce, to create a more level playing field.
As well as the benefits to health and quality of life, this strategy would be cost effective as the investment needed to reduce salt intake is far less that the amount needed to provide healthcare following a heart attack or stroke. In fact, the effects would be similar to tobacco reduction or prevention of obesity. High blood pressure costs the NHS over £2.1 billion every year.
Katharine Jenner, CEO of Blood Pressure UK explains: “The case was already incredibly strong, but these new studies further strengthen the case for a Government programme to reduce the amount of salt the food industry add to our food. Recent survey results show that our salt intakes haven’t fallen in the last few years, so it’s time the UK salt reduction strategy is stepped up.”
Professor Feng He, lead author of the Review and researcher at Queen Mary University of London, says:
“The totality of evidence in the JACC review and this latest BMJ research shows that reducing our salt intake will be immensely beneficial. Salt-reduction efforts should be reinforced in the UK and worldwide to save millions of people suffering and dying unnecessarily from strokes and heart disease each year.”
Professor Graham MacGregor, Professor of Cardiovascular Medicine at Barts and The London Hospital and Queen Mary University of London, Chairman of Blood Pressure UK and co-author of the reviews, says:
“Salt reduction is one of the most cost-effective strategies to reduce strokes and heart disease. The UK used to lead the world with an effective salt reduction policy whereby the food industry slowly reduced the unnecessary amount of salt they add to our food. This led to a reduction in salt intake and therefore blood pressure, with major reductions in stroke and heart disease deaths. More recently, previous governments have failed to continue this policy and the new government must now force the food industry to start making further reductions in the amount of salt they add to our food, either with legislation or financial penalties for those who fail to comply.”