As millions cut out animal products, farming conference hears that fruit and vegetables have been drained of nutrients

Advocates of red meat will begin a fightback against the growth of veganism this week at the UK’s biggest farming conference, with claims that eating lamb and beef is vital because some plants and fish are being drained of their nutrition.

In a speech at the Oxford Farming Conference, Alice Stanton will tell ministers, farmers and environmentalists that key nutrients in some fruits, vegetables and grains have dropped by up to 50% over 50 years.

Stanton, professor of cardiovascular pharmacology at the Royal College of Surgeons in Ireland, said nutrition levels had dropped because farmers were trying to meet a demand for cheap food. “For plant-based foods, there’s been drops in vitamins and key electrolytes by up to 50% over the past 50 years because of the genetic selection for large volume and uniformity of shape and appearance, so the things look good on the shelves. There hasn’t been selection for nutrient content,” she told the Observer.

Stanton has a significant interest in Devenish Nutrition, a global agri-technology company dealing in feed for livestock.

Growing interest in veganism and flexitarianism – people trying to eat less meat – led to a drop in sales of red meat last year of about £185m, according to market researchers Nielsen. Research for veganuary, which promotes plant-based diets on health and ethical grounds, showed that more than 1.3 million people gave up animal products in January 2019. Retailers and food companies have launched thousands of products aimed at vegans – nearly a quarter of all launches had a vegan claim, according to Mintel – including Gregg’s vegan sausage roll, vegan BBQ ribs and vegan smoked salmon.

“I’m not against vegetarianism or veganism,” Stanton said. “It is possible to have a balanced diet with vegetarianism. It’s a little bit more challenging but still possible with veganism. However, it requires a lot of knowledge and effort, which doesn’t happen in the majority of the population. People don’t have time to invest in getting a really balanced diet through a range of plant-based foods.”

Last year, the EAT-Lancet Commission, a group of 37 leading scientists, said that people in Europe and North America should reduce red meat consumption by about 80%, allowing for one beefburger and two servings of fish per week. Stanton said she “totally agreed” with its proposal for people to eat more pulses, nuts, fruits and vegetables.

Professor Stanton is right that a global shift in diet from meat to plant-based food won't be easy … but it's absolutely necessary Anna Jones, Greenpeace UK

“Absolutely, we need to address greenhouse gas emissions. But I’m concerned about the dramatic reduction in red meat consumption being regarded as the solution,” she said. Eating red meat in moderation – “twice to four times a week” – was “protective against heart attacks, strokes and cancer”, while nutrients in red meat were vital for children in the first three years of life, she added.

Stanton said plants were not the only foods declining in nutrional value. Studies also that show omega-3 fatty acid levels in Scottish farmed salmon have also dropped by half.

Will Jackson, of the livestock industry body AHDB, echoed Stanton: “The key message is balance. Different food groups work best when consumed together in moderation as part of a ‘balanced plate’ approach.”

Vegan advocates suggest buying organic food. “Organic producers often use more heritage strains of vegetables and grains that have not undergone as much selective breeding as more commercial strains,” said Toni Vernelli from the organisation Veganuary.

“Also, eat a wide variety of fruits, vegetables, nuts and grains to ensure you are getting a range of nutrients as well as an array of interesting tastes and textures.”

Anna Jones, a forestry specialist at Greenpeace UK, said: “Professor Stanton is right to point out that a global shift in diet from meat to plant-based food won’t be easy and isn’t a solution on its own, but, given the impact of the meat industry on the climate, it’s absolutely necessary.”

• This article was amended on 7 January 2020 to add a reference to Stanton’s interest in Devenish Nutrition.