The consumer group Which? says that, although some toddler milks contain more iron and vitaminD, they contain less calcium and more sugar than cow's milk.
This means that parents are wasting over Â£500 a year on specialist growing up milks when cow's milk would be sufficient.
A which? survey of 727 mothers with children aged between one and three found that 46% of them used these toddler milks despite government advice being that they are not needed.
The government recommends 300ml of cow's milk a day for toddlers, which provides all the calcium that a child of this age needs. These toddler milks do not says Which?
Which? also says that these products that contain vanilla flavouring, such as SMA Toddler milk, encourage children to prefer sweetened products.
Toddler milks are more expensive than cow's milk. The annual cost of providing a toddler with 300ml of cow's milk a year would cost just Â£62, but providing powdered milk would cost Â£235 a year and the ready made variety would cost Â£593.
Which? executive director, Richard Lloyd,Â said: 'At a time when so many household budgets are severely squeezed, parents could be saving hundreds of pounds on toddler milks that the government says are unnecessary.
'Ministers should make their advice much clearer and introduce guidance on the ingredients of toddler milks, including the level of sugar and calcium.'