Cow’s milk makes kids taller: study
Proteins may give children growth edge
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 the more noncow’s milk children drink, the lower their height.
For each daily cup of noncow’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 noncow’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 “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.
Yet many parents are replacing cow’s milk with alternatives made from soy, almond, coconut, rice and other “milks.” 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.
“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 threeyear-old, it may matter a lot in terms of growth.”
The study involved 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. 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.
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.”
In an email, PETA science advisor Dr. Frances Cheng said, “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 a few centimetres of difference isn’t indicative of stunted growth.
Macguire said while the shorter children may catch up, children tend to track along whatever growth trajectory they tend to be on, so the height differences might amplify over time.
In Canada, unlike the U.S., it is illegal to give growth hormones to dairy cattle.
IF YOU’RE NOT GETTING ADEQUATE NUTRIENTS YOUR HEIGHT WON’T BE OPTIMAL.