Stand your kid against the doorframe. Make a mark. Write the date.
That mark is the result of two things working together, and it's worth knowing which is which. One of them you can't do anything about. The other one is in your kitchen.
Try this: the pencil-mark experiment
Height in kids is not smooth. It comes in bursts. So mark the doorframe on the first of every month for a year and look at the gaps between marks.
You'll see fast months and slow months. Some of that is the calendar; kids put on more height in spring and summer. Some of it is sleep. And some of it, the part this post is about, is what went into the kid during those months.
The genetic part (most of it)
Let's be plain. About 80% of the difference in height between one kid and another is inherited. Tall parents, tall kids, more often than not. There's a rough formula pediatricians use, called mid-parental height: average the parents' heights, add about 2.5 inches for a boy or subtract 2.5 for a girl, and you have a target with a few inches of wiggle on either side.
Notice those words: a few inches of wiggle. That's the range genes leave open. And it's more than it sounds like. Two inches is the difference between the middle of a class photo and the back row.
The diet part (the part you control)
Here is the cleanest demonstration in all of nutrition science, and it's a whole country.
Around 1850, Dutch men were among the shortest in Europe, averaging about 5'5". Today they are the tallest people on Earth, over 6 feet on average. Seven inches in 150 years. Genes don't move seven inches in 150 years. Diet does, and the Dutch diet moved toward dairy, protein, and plenty of it.
The same thing shows up every time researchers look. In 2004, a Danish team measured 90 healthy toddlers and found the ones drinking more milk were taller and had 30% more IGF-1, the hormone that tells growth plates to build bone. In 2012, a meta-analysis of twelve controlled trials, where kids were actually given extra dairy, found about 0.4 cm of extra growth per year per cup of milk a day. The effect was strongest in teenagers and in kids already running short for their age.
That's the mechanism, and it's beautifully simple: genes decide how tall a kid could be. Nutrition decides how close they get.
The three nutrients that keep showing up
Every time a study finds diet moving height, the same three names come up.
Protein
Protein is the building material. Every new cell in a growing body is assembled from it. But it's also a signal. When a kid eats protein, especially animal protein, the body raises IGF-1, and IGF-1 is the message that says "build." A kid at the 10th percentile for protein intake is sending a quieter message than a kid at the 90th.
How much? About 0.95 grams per kilogram of body weight a day for ages 4 to 13. Roughly 19 grams for a first grader, 34 for a sixth grader. A glass of milk is 8. An egg is 6.
Calcium
Bone is roughly 65% mineral by weight, and that mineral is mostly calcium phosphate. You cannot build a taller skeleton without the material to build it from. Kids ages 4 to 8 need about 1,000 mg a day; ages 9 to 18 need 1,300 mg, because that's when the skeleton does its heaviest construction.
A cup of milk is about 300 mg. Most kids who don't drink milk fall well short, and nobody notices for years.
Vitamin D
Calcium in the stomach doesn't get into bone by itself. Vitamin D is the escort. Without enough of it, a kid can eat all the calcium in the world and absorb a fraction of it. Sunlight makes it; fortified foods carry it; in winter, at northern latitudes, most kids run low.
What "healthy diet" actually means for growth
You'll hear "a healthy diet" a hundred times and it's never defined. For growth specifically, it means this, and only this:
- Enough protein, spread across the day. Not one big dinner. Breakfast and lunch count.
- Enough calcium, most days. From milk, yogurt, cheese, fortified drinks, or leafy greens if you have that kind of kid.
- Enough vitamin D to let the calcium in.
- Enough total food. Chronic under-eating is the single biggest thing that stops a kid short of their range. Picky eaters, take note.
- Sleep. Growth hormone pulses at night. A kid who's up until 11 is skipping shifts at the construction site.
Everything else, the superfoods, the supplements with a basketball player on the label, is noise.
Where a juice box fits into this
Consider the afternoon. School's out, dinner's three hours away, and the kid wants something. That moment is a nutrition opportunity that almost always gets filled with sugar.
We built Wonderade for exactly that slot: 8 grams of protein, 300 mg of calcium, vitamin D, and 3 grams of sugar in a juice a kid asks for by name. One box covers a real share of a first grader's daily protein and a quarter of their calcium, at 3pm, without a negotiation.
To be clear: it supports normal growth the way a glass of milk does, by delivering the nutrients growth depends on. It doesn't change anybody's genes and it has not been studied for height. We'd rather tell you what the science says than what a poster says.
The full panel is here, next to a typical juice box.
FAQ
How much of a child's height is genetic? Roughly 80% of the variation between kids is inherited. Genes set a range of a few inches; nutrition, sleep, and overall health determine where in that range a child lands.
What foods help kids grow taller? The research consistently points at protein (especially dairy protein), calcium, and vitamin D, plus simply eating enough overall. Milk, yogurt, eggs, meat, beans, and fortified foods cover most of it.
Can a child grow taller than their parents? Yes, and it happens routinely when a child's nutrition is better than their parents' was. Population height rose seven inches in the Netherlands over 150 years on diet alone.
Does protein make kids grow? Protein supplies the building material and raises IGF-1, the hormone that signals bone growth. Kids need about 0.95 g per kg of body weight a day. More than that doesn't add height; too little can subtract it.
Does Wonderade help kids grow? Wonderade provides 8 g of protein, 300 mg of calcium, and vitamin D per box, the nutrients growth depends on, and supports normal growth as part of a healthy diet. It has not been studied for height and doesn't change a child's genetic range.
Want to fill the 3pm slot with something that does some work? We're sending free samples to founding families before launch. Claim your free sample. No commitment, just first access.