One-tenth of 50-year-old men have a heart age 10 years older than they are, heightening their risk of a fatal heart attack or stroke, a study suggests.
The Public Health England analysis is based on responses from 1.2 million people to its Heart Age Test - 33,000 of whom were men aged 50.
The organisation also predicts that 7,400 people will die from heart disease or stroke this month alone.
Heart disease is the main cause of death among men and second among women.
Most of these deaths are preventable and a quarter are people aged under 75.
"Addressing our risk of heart disease and stroke should not be left until we are older," PHE's head of cardiovascular disease Jamie Waterall said.
How to improve your heart health:
Give up smoking
Manage your weight
Eat more fibre
Cut down on saturated fat
Get your five a day fruit and vegetables
Cut down on salt
Drink less alcohol
Read labels on food and drink packaging