Eating too much salt increases risk of heart attack

People who eat too much salt over a prolonged period increase their risk of a heart attack, particularly if the heart is under strain. For the first time, researchers from the University Medical Center Groningen and Top Institute Food and Nutrition have established a link between high salt intake, an overburdened heart and an increased risk of heart attack. The results, which are based on the long-term Groningen PREVEND study, appeared online this week in the leading journal Circulation.

‘This study represents another piece of the puzzle proving that too much salt is detrimental to our health’, says UMCG researcher Michel Joosten. ‘In all probability, using less salt will reduce health risks, particularly for the group in the highest risk category.’ According to Joosten, the study supports arguments for reducing the amount of salt in processed food products. ‘On average, we get 75% of our daily salt intake from the food and drink we buy. Every gram of salt we consume on a daily basis that is surplus to our requirements increases our health risks.’

Marker

‘Our study examined the direct effects of salt on the heart. An increase in blood pressure or blood volume puts extra strain on the heart. Heart cells respond by producing substances to restore the balance. One of these substances was measured in the blood and turned out to indicate the link between salt intake and the risk of a heart attack.’ The researchers saw a clear link between salt intake and the risk of a heart attack in subjects with slightly or sharply increased NT-proBNP levels in the blood.

24-hour urine

Up until now, researchers had not found a clear link between salt intake and the risk of a heart attack. The fact that this has now been established is due to the ‘gold standard for salt intake’ used in this research. ‘This involves measuring the sodium level in 24-hour urine. The long-term Groningen population studies PREVEND and LifeLines enabled us to collect 24-hour urine samples from participants, who also filled in questionnaires about their diet. Nearly all previous epidemiological studies were based on data from questionnaires or portions of urine, which were not suitable for measuring salt intake with great accuracy.’

PREVEND

PREVEND is a long-term study designed to find ways of predicting renal and cardiovascular disease. The study has been monitoring a group of over 8,500 people for more than 15 years. Everyone taking part has collected all their urine for two days on several occasions. The sodium levels were reasonably consistent, giving an indication of the daily salt intake and lifestyle of the PREVEND participants.