In this review
In this review
Constipation and digestive discomfort are common in kids and are the reason for half of pediatric care visits.1 A critical reason? 95% of children do not consume the recommended amount of fiber.2 Fiber plays a key role in digestion, gut health, and overall wellness - and between picky eating and busy schedules - most children do not get enough. We enlisted the help of Jordan Thaler, RD, RDN, a Registered Dietitian Nutritionist specializing in children’s nutrition, to understand when children should take fiber supplements and the factors that actually matter when choosing one.
Combining Thaler’s guidance with hands-on testing from TCD parents on staff, we evaluated three of the most popular kids’ fiber supplements – Hiya Kids Daily Fiber+, Metamucil Kids Fiber Gummies, and SmartyPants Kids Fiber & Veggies. We’ll help you make an informed fiber supplement choice for your kids’ health and wellbeing.
One clear winner stood out in terms of formulation, form factor, and effectiveness. Read on to see our top pick.
Should My Child Take a Fiber Supplement?
We asked Thaler whether most children could benefit from additional fiber in their diet. Her answer: most of the time, yes.
High-fiber foods - broccoli, brussels sprouts, lentils - are what kids usually avoid; that’s why meeting kids’ recommended fiber intake of 19-25g per day is a challenge.
“Constipation and GI discomfort is very common in kids, usually due to low fiber intake,” Thaler says. “Fiber helps promote regular, comfortable bowel movements. It also supports immune health, feeds beneficial gut bacteria, helps maintain steady energy levels, and supports long-term metabolic and heart health.”
But it’s important to look at the age statement for fiber supplements. While children as young as 2 can benefit from fiber supplements, only one brand, Hiya, is listed as recommended for that age. SmartyPants and Metamucil are only safe for kids 4+ – more on that below.
Choosing the Right Fiber Supplement
What should you look for when choosing a children’s fiber supplement? For Thaler, it’s the combo of formulation and taste that will help support digestive health while still being tasty for kids:
- On what a fiber supplement should contain: “Look for fiber sources that are gentle and well tolerated. Supplements should include a mix of soluble and insoluble fibers. Soluble fiber feeds healthy gut bacteria, and helps stool stay soft and regular. Insoluble fiber adds bulk to stool and helps move digestion along.” Both are essential for digestive health.3
- On added sugar: “Added sugar can disrupt microbiome balance and contribute to cavities.” Kids get enough added sugar in their diet; they don’t need any extra.
- On format: “Powders or chewable tablets deliver higher amounts of fiber than gummies.”
- On taste: “For a supplement to actually help, kids need to take it regularly. The taste and format should be something children enjoy.”
How do Hiya, Metamucil, and SmartyPants compare when it comes to ingredients, form factor, taste (and more)? Let’s find out.
Fiber Supplements Compared:
Ingredients: Hiya Wins with the Most Fiber from Diverse Sources and Zero Added Sugar
Fiber supplement ingredient lists can be intimidating, often including unfamiliar fiber sources and sweeteners. But there’s one ingredient we always recommend avoiding in kids’ supplements: added sugar. Many brands add sugar to improve taste. According to pediatric dentists, sugars in gummies can stick to teeth and increase the risk of cavities.4 Excess sugar may also disrupt the balance of the gut microbiome and work against the digestive benefits fiber is meant to support.5
Hiya Kids Daily Fiber+ stands out as the one fiber supplement with zero added sugar or artificial sweeteners. Hiya’s fiber powder uses monk fruit for sweetness with zero added sugar or synthetic sweeteners. Metamucil also stands out with zero added sugar but adds Xylitol, a sugar alcohol, for sweetness. SmartyPants contains 1.5g added sugar per serving and uses Steviol Glycosides – both highly refined sweeteners.
Hiya also wins on fiber content and source. Hiya packs 6g of fiber per serving from a blend of soluble and insoluble fibers. It includes resistant vegetable fiber (an insoluble fiber) to help with regularity and add stool bulk, dragon fruit (a mixed fiber) to support gut bacteria & digestion, and inulin & psyllium husk (soluble prebiotic fibers) to feed beneficial gut microbes.
Metamucil & SmartyPants deliver less fiber from less diverse sources than Hiya. Metamucil has just 5g of fiber per 3-gummy serving from soluble fibers only (inulin, corn, & pectin). SmartyPants offers the lowest nutritional benefit with only 3g of fiber per 2-gummy serving, also from soluble fibers only (inulin & pectin).
For us, the trade-off is simple. Hiya delivers 6g of fiber from a blend of prebiotic and plant-based fiber sources in a simple two-scoop serving with 0g added sugar. Metamucil and SmartyPants rely on gummies with added sugars or sweeteners and lower, less diverse fiber.
Form Factor: Powder vs. Gummies: Hiya’s Powder Format Wins
In addition to ingredients, it’s important to consider the format of a child’s fiber supplement.
Hiya Kids Daily Fiber+ is a powder that can be mixed into drinks, smoothies, and yogurt. Metamucil and SmartyPants are both gummies. Gummies can contribute to cavities6 and rely on sweeteners to improve taste, which can increase the risk of overconsumption. Some nutrients (including fiber) are not stable in gummy form. Plus, lab testing has shown that gummies often have far above the listed amounts of various nutrients. Children can be particularly sensitive to these quantities.7 Finally, gummies can also be a choking hazard in children under the age of 4,8.9 which is why in this test, only Hiya is safe for kids 2+.
Thaler explains, “Powder fiber supplements like Hiya are a great option for kids because they deliver higher fiber, are easy to mix into foods and drink, and contain less sugar than gummies. Hiya’s powder format offers a more flexible and effective option than gummy supplements.
Taste: SmartyPants Wins
When it comes to kids’ supplements, taste matters. The highest-fiber supplement won’t help if children refuse to take it consistently.
For our kids, SmartyPants ranked first for taste. Its gummy format and added sugars makes it a sweet treat that kids enjoy. However, as parents, the added sugars and fewer fiber sources made us less enthusiastic about serving SmartyPants.
Hiya Kids Daily Fiber+ takes second with its Island Punch flavor. When mixed with water, it has a naturally sweet, fruity, and non-chalky taste. Our kid testers enthusiastically finished their glasses, and we felt better serving zero added sugar to our kids.
Metamucil comes in last place. Our testers complained it didn’t taste as good as Hiya or SmartyPants, and needed to be convinced to finish all 3 gummies.
Effectiveness: Hiya Wins with Improvement in Digestion
When choosing a fiber supplement, the most important question is simple: Which one actually works?
According to Thaler, “Fiber helps keep digestion moving and supports a healthy gut.” When fiber is doing its job, “We typically see more regular and comfortable bowel movements.”
To evaluate each brand’s effectiveness, our kids took each fiber supplement according to package instructions every day for two weeks. We noted any changes in digestion, comfort, and bathroom habits.
The results? In our study, Hiya Kids Daily Fiber+ wins with the most noticeable improvements in digestion. Our kids had fewer complaints about stomach discomfort compared to when they weren’t taking any supplements.
Metamucil and SmartyPants seemed to make little to no noticeable difference in digestive comfort or regularity during their testing periods.
Price: Metamucil Wins
For a supplement your kids will be taking daily, value is important. Each brand’s serving size delivers varying amounts of fiber; we compared prices per gram of fiber.
Metamucil is the cheapest at $0.16/g fiber from Target for sugar-packed gummies that our kids didn’t enjoy.
SmartyPants is $0.26/g fiber for gummies with added sugars and less fiber diversity.
Hiya Kids Daily Fiber+ is the best value at $0.32/g fiber with TCD’s discount for a sugar-free powder from diverse fiber sources that actually made a difference in our kids’ digestion.
The Overall Winner: Hiya
Which fiber supplement is best for your child? After our testing and analysis, we recommend the supplement that delivers 6g of fiber per serving, contains a proven blend of prebiotic fibers for digestive health, and has zero sugar. And that’s Hiya.
Thaler, our Registered Dietitian Nutritionist, agrees. “Hiya provides a balanced mix of fiber that supports both digestive regularity and gut health. It contains no added sugar and uses simple, transparent ingredients.”
Ready to try Hiya? With TCD, you can save 50% on your first order and get free shipping. Hiya also offers discounts for families with more than one child.
