People in Scotland, Wales and Northern Ireland have been advised to eat more like the English do, and live longer.
Oxford University experts claim 4,000 lives a year in the Celtic countries could be saved with a change in diet.
A new study by the experts has found people in England eat more fruit and vegetables and less salt and fat, reducing heart disease and some cancers.
A tax on fatty and salty foods and subsidies on fruit and vegetables could help close the diet divide, they add.
The British Heart Foundation says the study shows inequalities in the nations that must be addressed by authorities.
Death rates for heart disease and cancer are higher in Scotland, Wales and Northern Ireland than in England, according to official figures.
Lead researcher, Peter Scarborough of the Health Promotion Research Group said: "The chief dietary factor that is driving this mortality gap is fruit and vegetables.
"Consumption of fruit and vegetables in Scotland is around 12% lower than in England, and consumption in Northern Ireland is about 20% lower than in England. Consumption levels in Wales are similar.
"Other important factors are salt and saturated fat consumption, which are lower in England than in Wales, Scotland or Northern Ireland."
