The Role of Prebiotic Fiber in Kids' Gut Health (And Why Most Parents Overlook It)

If I told you that the key to your kid’s immune system, mood, and even focus might live in their gut, would you believe me?

I didn’t used to think much about it either. When I was researching what to put in NOT. Broccoli — the greens powder my husband Joshua and I created for our seven kids — I kept coming back to one ingredient that seemed almost too boring to mention: prebiotic fiber.

It turns out, boring is exactly what you want when it comes to gut health.

What Is Prebiotic Fiber, Anyway?

You’ve probably heard of probiotics — the “good bacteria” in yogurt and fermented foods. But prebiotics are different. They’re not bacteria at all. Prebiotics are a type of fiber that your kids’ gut bacteria eat.

Think of it this way: probiotics are the garden. Prebiotics are the fertilizer. You can plant all the seeds you want, but without something to feed them, they won’t thrive.

Most kids’ diets are pretty low in prebiotic fiber. We feed them plenty of food, but not a lot of the fiber-rich foods that actually fuel their gut bacteria — things like chicory root, garlic, onions, asparagus, and bananas.

Why Kids’ Gut Health Matters More Than You Think

Here’s what surprised me when I started digging into the research: the gut isn’t just about digestion. About 70% of the immune system lives in the gut. Kids with a healthy gut microbiome tend to get sick less often, recover faster, and even show better emotional regulation.

Gut bacteria also play a role in how nutrients are absorbed. If your kid’s gut isn’t in good shape, it doesn’t matter how many vitamins you give them — they may not be absorbing them efficiently.

That was a wake-up call for me. We spend so much time worrying about whether our kids are eating enough vegetables, but not nearly enough time thinking about whether their gut is prepared to use what they’re eating.

The Problem with Most Kids’ Supplements

When I was looking at other kids’ greens powders and vitamins on the market, I noticed something: almost none of them included prebiotic fiber. They’d give you a long list of vitamins and maybe some concentrated greens, but nothing to support the gut itself.

That felt backwards to me. If you’re trying to improve a child’s nutrition, you need to support the whole system — not just drop in a bunch of nutrients and hope for the best.

What We Added to NOT. Broccoli

One of the 10 ingredients in NOT. Broccoli is Chicory Inulin — one of the most well-researched prebiotic fibers available. Inulin is a naturally occurring fiber found in chicory root, and it’s been studied for its ability to feed beneficial gut bacteria, support digestive regularity, and help with mineral absorption.

We didn’t include it as an afterthought. We included it because if we’re going to give our kids a daily greens powder, we want it to actually support the whole picture — not just check a box.

The other nine ingredients are whole-food greens: Barley Grass, Spinach, Broccoli, Wheatgrass, Spirulina, White Beet Extract, Himalayan Pink Salt, Tart Cherry, and Apple Fruit Fiber. That last one — Apple Fruit Fiber — also contributes to prebiotic support, so we’ve got gut health covered from two angles.

Simple Ways to Boost Your Kids’ Prebiotic Intake

You don’t have to overhaul your family’s diet overnight. Here are a few easy ways to sneak more prebiotic fiber into your kids’ day:

• Add half a banana to a smoothie. Slightly underripe bananas are particularly high in prebiotic fiber.
• Sneak in onions or garlic wherever you can — they’re some of the richest prebiotic sources around.
• Mix NOT. Broccoli into their morning routine. One scoop (6.75g of real greens) in 6-8 oz of water, juice, or a smoothie. Unicorn Punch and Peach Ring flavors make it easy to get buy-in from even the picky ones.
• Don’t stress about perfection. Consistency matters more than a perfect diet. A little prebiotic fiber every day does more than a “perfect” week every month.

The Bottom Line

Gut health is one of those things that’s easy to overlook because the effects aren’t always immediate or obvious. But when I look at my own seven kids and how much better they feel when they’re eating well — including getting enough fiber — it’s hard to ignore.

If you’ve been focusing on vitamins and minerals but haven’t thought much about what’s happening in your child’s gut, this is a good place to start.

We created NOT. Broccoli because we couldn’t find a greens powder that did all of this well. It’s third-party tested, made in the USA, free of artificial ingredients, and designed for kids ages 4 and up. First subscription orders are 50% off — $24.50 for a 30-serving jar.

Your kid’s gut will thank you. (Even if they don’t.)

— Aubree