File photo: Participants had an average age of 60 and each was tracked for about five years.

Marriage may be the key to a longer life, experts say.

Those who have a spouse to care for them in sickness and in health are less likely to die from three very common health conditions than those who are single, a study found.

These conditions were high blood pressure, high cholesterol and type 2 diabetes – the biggest risk factors for heart disease.

Experts suspect this is because those who have the encouragement of a partner are more likely to take their medication, eat healthily and get enough exercise.

The study was one of the largest of its kind, with researchers analysing a database of more than one million patients between 2000 and 2013. Participants had an average age of 60 and each was tracked for about five years.

Those with high cholesterol were 16 percent more likely to survive that period if they were married than those who were not.

Married diabetes patients were 14 percent more likely to survive, while those with high blood pressure had a 10 percent higher survival rate, the study by Aston Medical School in Birmingham found. Lead researcher Dr Paul Carter, who presented the findings at the British Cardiovascular Society Conference in Manchester, said: "Our research suggests that marriage offers a protective effect, which is probably down to having support in controlling the key risk factors for heart disease.

"The findings shouldn’t be seen as a reason to get married, but as encouragement for people to build strong support networks with their families and friends."

Dr Mike Knapton, of the British Heart Foundation, said: "Our social interactions, as well as medical risk factors, are important determinants of both our health and wellbeing.

"Whether you are married or not, if you have any of the main risk factors for heart disease then you can call upon loved ones to help you to manage them."

Previous research has found married people are 71 percent more likely to survive a stroke and 14 percent more likely to survive a heart attack.