This advice comes after the British Nutrition Foundation (BNF) issued new guidelines on everything from portion sizes to limiting sugary foods.
The BNF note that vegan and vegetarian diets can be healthy for children, but they must get enough iron and zinc.
It recommends visiting the GP for advice about supplements and nutrients your child needs.
According to experts, it’s sometimes difficult to get enough vitamin A and B12, riboflavin, iron, zinc, calcium and iodine on a vegan or vegetarian diet.
Three portions of protein a day can alleviate that difficulty.
Non-meat protein sources include: beans, pulses, seeds, eggs, dairy and soy, amongst others.
It’s also suggested that children aged one to four are given five portions of starchy food per day, which includes bread, pasta, rice and potatoes.
If milk is not being offered to a child - in the case of a vegan diet - the BNF advise parents to seek medical advice regarding the supplements needed to balance the lack of dairy out.
The guide has laid out what constitutes as a portion. One slice of bread is deemed as a portion while two-five tablespoons of pasta is also one portion.
The latest guidelines show a crackdown on sugary food, claiming that it “should not form a regular part of a child’s diet”.
It urges parents to limit the amount of cakes, biscuits and other sugary treats they’re giving their children.
The guide has been released just months after Leeds was named as the first city in the UK to lower childhood obesity rates.
Leeds introduced the Henry programme in 2009. It formed the cornerstone of its obesity strategy. Henry, which stands for health, exercise, nutrition for the really young, was aimed at the youngest children (0-5 years) and poorest families in Leeds.