(CNN) Milk has had a bad rap in recent years. A rise in veganism and concerns around intolerance to the creamy white drink has seen a surge in popularity of milk alternatives, and multiple myths still surround the drink, including beliefs that it worsens the symptoms of a cold.

But when it comes to kids, cow's milk is a must-have -- and always in its fattiest form, experts say.

Milk is a good source of calcium, iodine, vitamins A and B12, and fat -- and it's the fat that helps children meet their energy requirements, says Lucy Upton, a specialist pediatric dietician and spokesperson for the Association of UK Dieticians.

"Fat is very important in children," says Upton. "They have very high energy requirements."

The three key energy sources for kids are dairy, protein and carbohydrates, and kids need significantly more energy per pound (or kilo) than adults. "The average two-year-old needs 80 calories per kilogram of weight," she says, highlighting that adults need less than half that amount.

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