Experts at the 50th Annual Meeting of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) are warning that young children who follow a vegan diet without medical and dietary advice carry the risk of a number of nutrient deficiencies, including vitamin B12, calcium, zinc and high quality protein, which can have potentially devastating health effects.

Studies have shown that children who follow a vegan diet are leaner and smaller than those children who consume meat or those who have vegetarian diets.

"It is difficult to ensure a healthy and balanced vegan diet in young infants, and parents should understand the serious consequences of failing to follow advice regarding supplementation of the diet. The risks of getting it wrong can include irreversible cognitive damage and, in the extreme, death. Our advice is that if parents pursue a vegan diet for their child, they must seek and strictly follow medical and dietary advice to make sure their infant receives adequate nutrition. Both mother and infant should follow advice regarding supplementation" advises Professor Mary Fewtrell, chairman of ESPGHAN's nutrition committee comments:

The biggest risk to vegan children is that of vitamin B12 deficiency. Foods derived from animals have been shown to be the only reliable source of vitamin B12 and a deficiency of the vitamin can have devastating effects. Vitamin B12 is essential to the creation of DNA, indispensable for the maintenance of the nervous system, and a lack of it can result in haematological and neurological disorders, causing damage in young children which can be irreversible.

Presenting to healthcare professionals at the ESPGHAN conference, Professor Myriam Van Winckel said: "The more restricted the diet of the child, the greater the risk of deficiency and this is by far highest in vegan children, but the risk does not stop there. Vegan mothers who breastfeed also need to be aware that their children can develop vitamin B12 deficiency between 2 and 12 months because of the lack of reserves in their body at birth, even if the mother is not showing any signs of deficiency herself."

Infants on vegan diets are also at risk of protein and calcium malnutrition, a situation made worse because parents can be misled by milk supplements. Rice milk, almond milk and soy milk suggest that they are suitable substitutes for milk, but experts say these should be properly labelled as 'drinks', because their nutritional value is not comparable to milk. Maintaining healthy levels of calcium is important for ensuring lifelong normal bone density, and rickets has been found in toddlers on a calcium-deficient diet consuming large amounts of non-supplemented soy drink.

However, unlike vegan diets, varied lacto (ovo) vegetarian and semi-vegetarian diets are generally safe. Although long term follow-up studies are scarce, they do not show a detrimental effect of vegetarian diets in children but instead point to beneficial health outcomes compared to omnivore diets, such as favourable lipid profile, antioxidant status, dietary fiber intake as well as tendencies towards a lower risk of being overweight.