Professor Robert Pickard, from the University of Cardiff, claims “new year” diet changes such as Veganuary, where people sign-up to go vegan next month, means they will lack the health and nutritional benefits that are found in meat and dairy products.

He claims many plant-based alternatives are actually packed with artificial ingredients and meat-free alternatives available in restaurants and supermarkets like “bleeding veggie burgers” have to go through extensive chemical processes to mimic the taste and texture of the real thing.

According to Pickard, plant-based products are often viewed underneath a “health halo”, but are more processed than natural, lean cuts of meat.

The professor forms part of the Meat Advisory Panel (MAP) – a group of healthcare professionals, scientists and researchers who provide independent information about red meat and its role as part of a healthy balanced diet. MAP is supported by an unrestricted educational grant from the red meat industry.

Prof Pickard said: “Many believe that plant-based products are superior, simply because they are ‘plant-based’.

“However, many vegan products are becoming increasingly processed.

“This can leave some alternative products lacking in the health and nutritional benefits that are found in meat and dairy. Many still believe that replacing meat and dairy with processed alternatives will benefit their health.

“For example, a high-quality beef burger is a source of vitamin B12, essential for DNA production and body repairs.

“However, this is not found in a corn or chickpea burger. Similarly, a sweetcorn burger is deficient in lysine and without lysine our protein production can be stalled significantly.”

Pickard went on to extol the virtues of eating a varied diet, including animal products. He said lean red meat had a large range of nutrients, including vitamin D, iron and high-quality protein.

However, Go Vegan Scotland was quick to challenge Pickard’s views, saying he had “forgotten to mention that plant-based meat, fish and dairy alternatives do not come laden with saturated fat, cholesterol, mercury or antibiotics, all things we should avoid”.

It also said MAP cannot be “independent” or “objective” as it was funded by the meat industry and described them as a “voice box” for that body.

A spokesperson for Go Vegan Scotland said: “There’s an awful lot of scaremongering going on.

“The meat and dairy industries can see as well as anyone else the exponential increase in plant-based eating and they’re openly throwing a lot of money at campaigns to try to put people off.

“The meat and dairy industries can’t address the moral argument, that we shouldn’t be using and killing animals, and they can’t undermine the environmental case for switching to plant-based production, because the evidence is coming thick and fast and from the most credible sources that we must move away from animal agriculture if we’re to have any hope of halting climate change.

“Therefore, they have opted to attack the health side of things.

“There is no doubt that we can get everything we need on a good plant-based diet and this is recognised by the British Dietetics Association, the US Dietetics Association and our NHS.

“We simply do not need to consume animals or anything taken from animals to live well, indeed to thrive, and that includes many top athletes.”

They added: “It is a myth that vitamin B12 comes from animal products.

“B12 is produced in the soil by microbes.

“In the past we and animals would obtain B12 when we ate vegetables.

“Now our soil is so depleted due to animal agriculture and pesticide usage that we all need to take supplements, including animals who are given it in their feed or injected with it.

“We are all taking B12 supplements, whether first hand or second hand through animal products.”

The World Health Organisation (WHO) said in 2015 that processed meats such as bacon, sausages and ham do cause cancer.

Its report said 50g of processed meat a day – less than two slices of bacon – increased the chance of developing colorectal cancer by 18 per cent.

Meanwhile, the WHO said red meats were “probably carcinogenic”, but there was limited evidence. The organisation did stress that meat also had health benefits.

Pickard said: “Processed meat does contribute to a healthy balanced diet, but it is too nutritious to be eaten in large quantities by sedentary people because it usually contains additional fat, which is undesirable for people trying to lose weight.

“The processes that are used to preserve meat, which include curing, salting and smoking, all have to meet the safety standards of the countries in which they are undertaken.”

A total of 168,542 people this year signed up for Veganuary – a 183 per cent increase on the 59,500 who took part in 2017.

Heather Russell, dietician for The Vegan Society, said: “The Vegan Society works with the British Dietetic Association to share the message that well-planned vegan diets can support healthy living in people of all ages.

“They feature health-promoting plant foods like whole grains, fruit, nuts, seeds and vegetables and exclude animal products like processed meat and red meat, which the World Health Organisation categorises respectively as an agent that causes cancer and an agent that probably causes cancer.”

Taking meat off the menu '˜could damage health', warns academic