The supermarket is working with researchers to see if an app could help customers to make healthier choicesALAMY

People who shop at Waitrose are to be given “nudges” towards healthier food choices based on their DNA.

The supermarket is working with researchers at Imperial College London to see whether individual advice based on a person’s genes can cut their chance of developing type 2 diabetes.

Participants’ saliva will be scanned to look for markers that show if they are prone to obesity or high blood pressure, or slow to metabolise caffeine.

When they scan the barcode of food they want to buy with an app, they are given either a red thumbs down and a choice of food in the same category that might be a better idea, or a green thumbs up.

Someone at risk of developing high blood pressure might be…