Excess salt intake is a major cause of high blood pressure (hypertension). However, people with this condition are failing to lower their salt intake to reduce risks to their heart, and are instead relying on medication, a new study has found.

Until now, there has been little research into the relationship between salt intake and blood pressure in patients who are already being treated for the condition with medication. Japanese researchers decided to look into this further.

They found that a lack of adherence to lifestyle changes recommended by their doctors was leading to a higher salt intake among patients with high blood pressure. This meant more medications were needed, leading to potentially more side-effects from these drugs.

"Patients may be able to improve this vicious cycle by restricting salt intake. In consequence, they may avoid diseases caused by hypertension, such as heart attacks, stroke and heart failure. Moreover, they may be able to avoid side-effects from antihypertensive drugs, such as dizziness and fainting," commented the study's lead author, Dr Kazuto Ohno, of the Enshu Hospital in Japan.

The study involved over 12,400 patients who were taking blood pressure medicines. Their health and salt intake was monitored over a seven-year period.

The researchers found that while blood pressure levels improved during this period, salt intake increased across the board.

"Although blood pressure values in hypertensive patients had lowered, salt intake was gradually increased. We think improvement in blood pressure control is not due to salt restriction, but due to drug treatment," Dr Ohno said.

Overall, less than 4% of patients were following the salt intake recommendations given to them by their doctors. Furthermore, salt intake tended to be higher among those taking multiple blood pressure drugs compared to those taking just one drug.

"We think salt restriction is an important modifiable factor of lifestyle to treat and prevent high blood pressure, but more awareness about the harms of higher salt intake is needed in both hypertensive patients and healthy people.

"We can check the amount of salt in a lot of food and seasoning, such as soy sauce, mayonnaise and so on, which are printed on the food labels. However, it is impossible to measure salt intake in every meal, so all of us should try to take food with reduced salt by referring to food labels," Dr Ohno added.

Details of these findings were presented at the ESC (European Society of Cardiology) Congress 2018 in Munich.