Growth Science
For how much calcium and protein milk actually delivers, and how it stacks up against other sources, see our calcium guide and protein guide. This piece answers a narrower, more specific question: does drinking milk itself — beyond just being one convenient source of calcium and protein — actually make kids grow taller? The honest answer from the research is more nuanced than either "yes, obviously" or "no, it's a myth."
The Short Answer: It Depends on the Type of Evidence
"Does milk help kids grow taller" gets answered differently depending on what kind of study is asked. Three distinct types of evidence exist on this question, and they don't all point the same direction — which is exactly why the honest answer isn't a simple yes or no.
| Evidence Type | What It Actually Shows | Can It Prove Cause and Effect? |
|---|---|---|
| Randomized trials (height) | No significant height difference between milk-supplemented and control groups in well-nourished 6–18 year olds | Yes — and the answer for height specifically is "no measurable effect" |
| Randomized trials (bone mineral content) | Dairy supplementation significantly increases bone mineral content, even though height itself doesn't reliably move | Yes — effect confirmed for bone density, not the same as height |
| Randomized trials (IGF-1 hormone) | Milk raises IGF-1 (a growth-related hormone) more than an equal amount of protein from meat | Yes — a milk-specific biological effect exists, separate from total protein |
| Observational / cohort studies | Children who drink more cow's milk tend to be taller than children who drink plant-based milk instead | No — correlation only; diet quality and other factors aren't fully separated out |
What the Best Evidence (RCTs) Actually Shows
The most reliable way to test "does X cause Y" is a randomized controlled trial: give one group of kids extra milk, give another group none, and measure what actually changes. Two large studies have done exactly this. Here's what they found, in plain terms:
Put simply: extra milk clearly helps kids build stronger bones and gain healthy lean mass. It just hasn't been shown, in controlled trials of well-nourished kids, to make them measurably taller. Denser bones and taller bones are related, but they're not the same result — and it's the height result specifically that the evidence doesn't support.
Is Milk Special, or Just a Convenient Protein Source?
Here's a simple experiment that answers this directly. Researchers took 24 eight-year-old boys and split them into two groups for one week. Both groups ate the same amount of extra protein — one group got it from milk, the other from meat. Everything else about their diet stayed the same.
Both boys ate roughly the same extra protein. Only the milk group saw their IGF-1 — a hormone tied to the body's growth signaling — go up. So milk isn't just a stand-in for "protein" in general; something about milk itself, likely its specific mix of proteins and minerals, does something extra.
But an IGF-1 bump isn't the same as extra height. IGF-1 is one piece of a much bigger growth puzzle, not a direct stand-in for centimeters gained. As the stat cards above show, controlled trials in well-nourished kids haven't found that this hormone effect actually turns into measurably taller children.
What About Kids Who Skip Cow's Milk?
A large study followed over 5,000 Canadian children, ages 2 to 6, and simply asked: does drinking more plant-based milk (soy, almond, oat, and similar) line up with a shorter height?
This is a correlation, not proof of cause and effect. Kids weren't randomly assigned to one milk or the other — families choosing plant milk may simply differ in overall diet, and the researchers themselves said cow's milk intake only partly explains the height gap. The honest takeaway: if a child drinks mostly plant milk, it's worth double-checking their overall calcium and protein intake — not assuming the plant milk itself is the problem.
What This Means in Practice
A note on undernourished populations: most of the research above involves already adequately-nourished children in higher-income settings, where milk is one option among several for meeting nutrient targets. In settings where children are genuinely deficient in protein, calcium, or overall calories, milk supplementation has shown clearer growth benefits — because it's correcting an actual shortfall, not adding to an already-sufficient diet. The relevant question for most families isn't "does milk add extra height on top of an adequate diet," but "is my child's overall diet, milk or otherwise, meeting calcium and protein targets" — covered in full in our calcium guide and protein guide.
Frequently Asked Questions
So does milk make kids taller or not?
In children who are already meeting their nutrient needs, controlled trials have not found that milk supplementation produces a measurable height difference, even though it does increase weight, lean mass, and bone density. Milk does raise IGF-1 more than an equivalent amount of meat protein, showing a real, milk-specific biological effect — but that hasn't been shown to translate into extra height in well-nourished children specifically.
If milk doesn't add extra height, is there any point drinking it?
Yes. Milk remains one of the most efficient, well-studied ways to meet daily calcium and protein targets, and dairy supplementation has a well-established, positive effect on bone mineral content — which matters for lifelong bone health even separate from the height question. The point isn't that milk is unimportant; it's that milk on top of an already-adequate diet isn't shown to add extra centimeters.
Are kids who drink plant-based milk instead of cow's milk shorter?
A large observational study found children drinking more plant-based milk measured somewhat shorter on average, but this is a correlation from a study where children weren't randomly assigned to drink one milk type or the other. Families choosing plant milk can differ in overall diet, and the study couldn't fully rule out these other factors. It's a reasonable prompt to check a plant-milk-only child's overall calcium and protein intake, not proof that plant milk itself limits growth.
Does the type of milk (whole, skim, fortified plant milk) matter for growth?
The IGF-1 research specifically used skimmed cow's milk, and the noncow milk research grouped several plant-based options together, so the evidence doesn't cleanly separate out every variety. What's consistent across studies is that fortified plant milks can match cow's milk for calcium when checked against the label, though they contain different proteins and lack the casein/whey combination studied in the IGF-1 research.
Should a child drink extra milk specifically to try to grow taller?
Based on the RCT evidence in well-nourished children, deliberately increasing milk intake beyond what's needed to meet calcium and protein targets has not been shown to add height. A more evidence-based approach is ensuring the calcium and protein targets are met — through milk or an equivalent combination of other foods — rather than treating extra milk as a standalone growth intervention.
