Children who drink non-dairy milks tend to be shorter than cow’s milk drinkers: Canadian study


Children who drink soy, rice or almond milk may end up shorter than children given cow’s milk, a new study suggests.

Toronto researchers are reporting that the more non-cow’s milk children drink, the lower their height.

For each daily cup of non-cow’s milk consumed, children were 0.4 cm shorter than dairy milk drinkers. At age three, the height difference between children who drank cow’s milk versus non-cow’s milk was 1.5 cm.

The researchers say it’s not clear what might be happening at a biological level to produce the effects, but others have hypothesized that milk proteins and insulin-like growth factors that occur naturally in cow’s milk give children an edge in their “linear growth.”

While the findings don’t prove cause and effect, only an association, they are raising questions about the perceived health benefits of — and surging demand for — mock milks.

“Cow’s milk is a staple for most North American children and is an important source of dietary protein and fat, two essential nutrients for optimal growth,” the researchers write in the American Journal of Clinical Nutrition.

If you’re a three-year-old, it may matter a lot in terms of growth

Yet many parents are replacing cow’s milk with alternatives made from soy, almond, coconut, rice and other “milks” not squeezed from the teats of dairy cows. Surveys suggest 12 per cent of children in urban Canada are drinking plant-based and other non-cow’s milk beverages, while Canada’s per capita consumption of dairy milk plummeted by 22 per cent from 1996 to 2015.

Sales of almond milk alone tripled from 2014 to 2016, according to market research firm Nielsen. Overall, sales of soy, rice and other milk substitutes topped $281 million in the year ending April 29.

“Drinking cow’s milk is something that almost every child in North America does, but increasingly parents are choosing other kinds of milk, because there’s a perception of health benefits,” said Dr. Jonathon Macguire, a pediatrician at St. Michael’s Hospital in Toronto and lead author of the new study.

However, the protein and fat content of milk substitutes varies widely, and there’s very little regulation of their nutritional content, Macguire said.

“If you’re an adult, that probably doesn’t matter that much. But if you’re a three-year-old, it may matter a lot in terms of growth.”

The study involved a total of 5,034 children aged 24 to 72 months. Of those studied, 92 per cent consumed cow’s milk and 13 per cent non-cow’s milk daily. Children were excluded from the study if they had a known condition affecting growth.

The researchers found a dose-dependent association between higher non-cow’s milk consumption and lower height. Simply put, “children who are consuming non-cow’s milk tended to be a little shorter,” Macguire said. The association held after they adjusted for age, ethnicity, socioeconomic status and other factors.

“When you’re a little person your intake of fat and protein and micronutrients is really important, because you’re growing quickly. That’s why height is such a great marker of children’s health — if you’re not getting adequate nutrients your height won’t be optimal for you,” Macguire said.

“We have lots of experience with cow’s milk,” he added. “It seems to work. Kids have been drinking cow’s milk for a long time in North America and they seem to do just fine. We know less about the alternative milks.”

Some children are allergic to cow’s milk. Some are lactose intolerant. There could be other health advantages to consuming non-cow’s milk, Macguire acknowledged. However, “if you look in the literature, there’s not a whole lot.”

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The animal rights organization PETA has linked dairy milk to autism and recommends a “switch to healthy vegan alternatives instead.”

In an emailed statement to the Post, PETA science advisor Dr. Frances Cheng said that, “While it’s certainly true that cow’s milk contains a growth hormone that can make kids grow more at the rate of a calf than a human child …. this (new) study is so limited that few, if any meaningful conclusions can be drawn from it.”

The study wasn’t randomized and didn’t track what the children ate or drank apart from milk, Cheng said. “Key information, such as how much protein and fat the children ingested, is missing entirely.”

The study also focused on children ages two to six, “even though kids aren’t fully grown until well into their teenage years,” said Cheng, who argues that a few centimetres of difference in height isn’t indicative of stunted growth.

Macguire said that while the shorter children may catch up, children tend to track along whatever growth trajectory they tend to be on, so that the height differences might amplify over time. “Even a one- or two-centimetre difference when you’re little can result in a big difference when you’re an adult,” he said.

In Canada, unlike the U.S., it is illegal to administer growth hormones to dairy cattle.

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