Older varieties of fruit and veg may be considerably healthier than their modern supermarket equivalents, researchers claim.
A pilot study found that an unfashionable dessert apple which dates back to Victorian times had ten times more of a disease-preventing chemical than its newer, shiny-skinned equivalents.
A team of scientists will now undertake a three-year study, examining older varieties of apples, bananas, onions, mangos and teas.
They've already found that the Egremont Russet apple, which is often used to make cider, contains considerably more phloridzin than modern glossy fruits. The chemical increases the absorption of sugar from the digestive system into the blood, and can reduce the risk of type 2 diabetes.
While the Egremont Russet is widely available, the researchers stressed that it has not been intensively farmed for a higher yield and pristine appearance, which can substantially reduce nutrient levels.
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.