This is The Telegraph, so apologies for the weird choice on percent and other style quirks.

The nutritional value of fruit and vegetables has fallen by up to 50pc since the Sixties because of declining soil quality, according to a new study.

The report, from researchers at Deep Science Ventures, found that humans needed to consume twice the number of vegetables to get the same level of minerals such as potassium, magnesium or copper as would have been present in their food 60 years ago.

The study found that many crops had lost 20pc to 50pc of several key nutrients.

Will Summers, a senior associate at the firm, said: "For 60 years we've measured food security in calories and tonnes per hectare.

"On those measures we've done remarkably well. But we've been quietly hollowing out what's inside our food."

The decrease in nutrient and vitamin value is thought to be down to declining soil quality and crops being selectively bred for their ability to grow quickly, rather than there being any focus on their health benefits.

The effect will be particularly acute for the 14pc of Britons who identify as vegetarian or vegan.