The scientists at Unilever, Kew Gardens and Cranfield University in Bedfordshire, believe "pre-domesticated" fruit and veg eaten in years gone by had higher levels of hundreds of chemicals that help prevent disease. These include salicylates, which are used to make aspirin and play a key role in fighting cancer.
Today, some mass-produced fruits and vegetables are stored for months at a time in cold conditions to slow the ripening process. This process depletes the vitamins in the skin.
Plus, supermarkets select the best-looking stock when, in fact, plants produce more nutritious chemicals if they have bruises, as these are produced as a defence mechanism against threats.
Professor Leon Terry from Cranfield University said a "paradigm shift" was required to promote foods based on their health-boosting properties, not their appearance.
Lead researcher Dr Mark Berry added: "In the Stone Age people would have eaten 20 or 25 different types of fruit and vegetables every day. Now we tend to breed and eat a few of the same ones all the time.
"We are very interested in whether older varieties of plants have higher levels of nutrients, which we don't get nearly enough of in our diets."
It could eventually be possible for wholesalers to grow more nutritious varieties from dozens or even hundreds of years ago.
DAILY MAIL