Doctors in Belgium have called for parents who raise their children as vegans to face prosecution after a number of deaths in schools, nurseries and hospitals.
It is estimated that 3 per cent of Belgian children are forced to follow the strict diet, which rules out any animal products, including dairy and eggs.
The Royal Academy of Medicine of Belgium published a legal opinion on Thursday, which could influence future court judgements and is the first time a health authority has taken a position on veganism in the country.
The opinion said it was unethical to subject children to the diet because it didn't include animal proteins and vital amino acids which can help growth and prevent health problems.
The vegan diet could only be made safe for growing children if complemented with medical supervision, regular blood tests and vitamin supplements, which most parents were not qualified to provide.
"We must explain to the parents before compelling them," said Professor Georges Casimir, who led the commission that wrote the report, "but we can no longer tolerate this endangerment."
"This restrictive regime requires ongoing monitoring of children to avoid deficiencies and often irreversible growth delays," the legal opinion said, "It is unsuitable for unborn children, children, teenagers and pregnant and lactating women."
"It is not medically recommended and even forbidden to subject a child, especially during periods of rapid growth, to a potentially destabilising diet, requiring frequent supplementation and control," it said.
"This concept of nutrition is similar to a form of treatment that it is not ethical to impose on children."
The opinion was published after a request by Bernard Devos, a regional government official responsible for children's rights and protection in Brussels and the French-speaking region of Wallonia.
Devos asked for the opinion after children suffered health complications, including a number of deaths, in schools, nurseries and hospitals, Belgium's Le Soir newspaper reported.
It would make it easier for him to enforce the separation of a child from parents who insisted the youngster followed the restrictive diet.
Professor Casimir warned that such a strict regime would now legally qualify as "non-assistance to a person in danger", a crime which carries a sentence of up to two years and fines in Belgium.
A person cannot be convicted of the 1961 offence if he is unaware the person is in danger but the legal opinion now made it common knowledge that a vegan diet can kill, he told Le Soir.
The pediatrician said, "When we are children, the body manufactures brain cells. This implies higher requirements for protein and essential fatty acids. The body does not produce them, it must be brought in via animal proteins.
"We are talking here about stunted growth and psychomotor delays, undernutrition, significant anemia. Some developments must be done at a specific time in life and if they are not done, it is irreversible."
Dawn Carr, of PETA, said, "What a load of ignorant codswallop! NHS nutritionists confirm that while a meat- and dairy-based diet is what strikes people down in adulthood – as it can lead to hardened arteries that cause stroke, brain aneurysms, and heart attacks – a well-planned vegan diet is perfect for babies and children.
"Kids, including my own, thrive on a balanced vegan diet, but as with any dietary regime, it's the parent's responsibility to ensure their child is getting all the necessary nutrients. And yes, that's easier to achieve on a vibrant vegan diet rich in whole grains, vegetables, and pulses."
Heather Russell, dietitian at The Vegan Society, said: "Nutritional planning is important for everyone, not just vegans. It's possible to provide all the nutrients needed for growth and development without animal products."
"Both the British Dietetic Association and the American Academy of Nutrition and Dietetics recognise that well-planned vegan diets can support healthy living in people of all ages, including infants, children, teenagers and pregnant and breastfeeding women," she added.