Hi the labelling system on foods is regulated by law so the information on every product should be reliable enough for it to be used to work out how much fat, protein and carbohydrate is being added to a snack or meal.
http://www.nhs.uk/Livewell/Goodfood/...labelling.aspx
Settings are required to plan healthy nutritious meals and provide suitable drinks for children so this information is valuable to them.
Eat Better Do Better campaign (if you're working in england)
and this
quote from page 28 of EYFS, again only if you work in england, the
other home nations have their own frameworks and healthy eating programmes.
Food and drink
3.47. Where children are provided with meals, snacks and drinks, they must be healthy, balanced and nutritious. Before a child is admitted to the setting the provider must also obtain information about any special dietary requirements, preferences and food allergies that the child has, and any special health requirements. Fresh drinking water must be available and accessible at all times. Providers must record and act on information from parents and carers about a child's dietary needs
Hope this helps xx
& 
Linear Mode
