Milk does a body good -- or at least at least that's what we have long been led to believe. But a new book argues that milk is not quite the superfood many of us may think.

In her book "Got Milked?” author Alissa Hamilton argues that many of us have been pulled into what she calls the great dairy deception: the belief that milk is critical for bone and dental health, and an essential part of a healthy diet.

Hamilton, who holds a Ph. D in Forestry and Environmental Studies from Yale University, says she was inspired into looking into milk after a friend of hers confessed that her two-and-a-half-year-old son Oscar had still not tried milk. The mother was feeling guilty about it and Hamilton wondered why, since she herself had grown up not drinking milk either.

"What if she had said, 'I haven't given Oscar kale and he's 2-1/2; what do I do?' We all know that Oscar will be fine without kale but we all think that without milk, he's going to fall apart," Hamilton told CTV's Canada AM on Wednesday.

Hamilton doesn't believe that milk is necessary for a healthy diet, but says the idea it is has been drilled into consumers, thanks in large part to messaging from government health bodies and dairy groups’ marketing campaigns.

But Hamilton contends that there are plenty of cultures that thrive without three servings of cow's milk a day, and in fact, they may be healthier in some ways.

"Singapore, Hong Kong – the countries with the lower calcium intake have the lowest bone fracture rates as well. And in fact, the countries with the highest calcium intake rates have the highest hip fracture rates," Hamilton said.

"This is what has led to what the World Health Organization recognizes as the calcium paradox."

Hamilton has learned that 60 per cent of North American adults are actually lactose intolerant. "We're told it's an essential part of a healthy diet and yet most of us can't even digest it," she says.

Not only is dairy unnecessary, it can even be harmful in large amounts. She says many pediatricians are regularly seeing kids who are anemic or iron-deficient from drinking too much milk.

"We've heard about the wonders of milk and yet there are downsides we don't hear about and that we might want to know more about before rushing to fill that three servings per day recommendation – which is not evidence-based," she says.

Hamilton also finds it odd that dairy foods are given their own food group in the Canada Food Guide, saying milk doesn't deserve this special status any more than pumpkin seeds deserve to be their own food group because they’re high in magnesium.

As for worries about calcium, Hamilton says there are plenty of vegetables that are rich in the mineral. A cup of soybean sprouts, for example, has 400 mg of calcium, which is close to the 500 mg recommended as a minimum daily value by the WHO.

"So calcium is everywhere. We have this idea about milk and it's served a crutch for all of us, so we don't know about all the other sources of calcium all around us," she says.