Salt raises your blood pressure, even if you eat a healthy diet
New research supports eating less salt as the most important thing you can do to lower your blood pressure
Eating an otherwise healthy diet does not counter the effects of eating too much salt, according to a new study published this March in the journal, Hypertension. Researchers looked at the amount of salt people ate along with their overall diet and their blood pressure and found that salt directly raised blood pressure regardless of the other nutrients in their diet.
Why was this study done?
There is overwhelming evidence showing direct relationship between salt intake and blood pressure, but most studies didn’t look at the whole diet and blood pressure. The authors wanted to find out whether other nutrients in the diet could affect the relationship between salt and blood pressure – either raising blood pressure further or reducing the effect of salt.
What did the study involve?
Researchers from Imperial College London and Northwestern University, along with colleagues in the US, China and Japan, looked at the diets of 4,680 people aged 40-59 along with their blood pressure and the amount of sodium in their urine - an accurate way of measuring salt intake.
The researchers used data from the INTERMAP study (International Study on Macro/Micronutrients and Blood Pressure), an important study carried out from 1997-1999 which aimed to understand the relationship between salt intake and blood pressure.
What did the researchers find?
The team found that salt directly raised blood pressure, and the amount of saturated fat, fibre, vitamins and minerals in the diet made little difference.
Potassium, which is found in fruit and vegetables, did have some effect on reducing the effect of salt, but only at lower salt intakes.
What does this study add?
This adds to the existing evidence that eating less salt is the most important change you can make to your diet to lower your blood pressure.
The authors advised: "To prevent and control the ongoing epidemic of prehypertension and hypertension, major reductions are needed in the salt content of the food supply."
What are the limitations of the study?
Despite considering other factors such as smoking and physical activity, the authors can’t rule out that other factors could have played a role. The information about what people ate was based on people remembering what they ate over a 24-hour period which may not have been completely accurate.
Professor Graham MacGregor, Chairman of Blood Pressure UK, says: “We are all eating too much salt. It puts up our blood pressure, leading to tens of thousands of unnecessary strokes and heart attacks every year.
“This study confirms the urgent need for action from the Government and the food industry to step up and add less salt to our food, as the majority of our salt intake comes from processed foods. It is the most cost-effective measure to reduce the number of people dying or suffering from strokes and heart disease.”
Nirmala Markandu, Hypertension Nurse Specialist at Blood Pressure UK, adds:
“This study shows that eating less salt is the key to a blood pressure-friendly diet. It doesn’t mean the rest of your diet doesn’t count. Eating lots of fruit, vegetables and fibre, less saturated fat and keeping an eye on your calorie intake will give you the right balance of nutrients to stay healthy and stave off numerous diseases including heart disease and stroke.
“Eating less processed foods, checking the labels to compare products and cooking at home with no added salt will all help.”
Read more
See how you can eat less salt.
Read an in-depth analysis of the study in the NHS’s Behind the headlines
See the original study