Fiber One is one of the most popular fiber brands in the U.S. They sell protein bars, treats, cereals, breads and much more, all of which are high in fiber.
But are Fiber One products healthy or are they too "processed"? Do they contain any unhealthy additives? Do they provide an effective fiber dose? And what was our honest experience trying them?
In this article we’ll answer all of these questions and more, as we analyze the ingredients in two of the most popular Fiber One products (Fiber One bars and Fiber One cereal) to give our take on whether or not they're healthy, and whether or not they provide enough fiber.
We’ll also share our experience purchasing and trying them, feature an interesting video on whether you can OD on fiber, and compare Fiber One to other popular fiber-rich products like fiber gummies to pick our winners (and losers).
Key takeaways:
- Healthy, high fiber content
- Additive ingredients we consider unhealthy
- We do not currently recommend Fiber One
Fiber One Bars Ingredient Analysis
The ingredients in Fiber One Caramel Nut protein bar are shown below:
The good news is that most of the calories come from whole food ingredients.
Chicory root extract was described as a “functional food” in a medical review published in the Nutrients journal.
The study authors found that it can help feed beneficial strains of bacteria in the gut, and can reduce blood cholesterol levels and food cravings.
Roasted peanuts are an excellent source of nutrients, providing a significant amount of calcium, magnesium, phosphorus and potassium according to the USDA.
This product also contains 8 grams (g) of dietary fiber per bar, which is a significant amount. As we documented in our review of fiber gummies, a diet containing over 35 or so grams of fiber can reduce the risk of obesity and heart disease.
Unfortunately, there are also some additive ingredients in this bar that are questionable from a health perspective.
Corn syrup is one of the sweeteners used, and a 2009 medical review found that high-fructose corn syrup intake is associated with a range of negative health outcomes and may contribute more to obesity than table sugar.
Carrageenan is a thickening agent that was shown in animal studies to cause gut dysfunction. The researchers from the linked study suggested that it should be removed from the Western diet.
Natural flavor is a broad categorical term that fails to describe the specific flavoring agents used. A medical review published in the Environmental Health Perspectives journal documented that some natural flavors and their metabolites may be toxic.
Overall, we do not currently recommend Fiber One bars due to the ingredients highlighted above.
We Tested Fiber One
As the author of this article, I wanted to purchase and try Fiber One myself to share my thoughts on its taste and effects.
I had barely eaten anything all day, and purchased the peanut butter and blueberry-flavored bars and ate them before going to the gym to lift weights.
Both the texture and the taste of both bars were excellent, though I slightly preferred the peanut butter flavor. These bars are sweet but not too sickly sweet, and the peanut flavor had a soft, chocolate outside and a slightly more crunchy and textured inside.
I felt significantly stronger during my workout and was able to perform more reps on my max lifts than usual.
I typically workout fasted, and the fact that these bars each contained over 250 calories and a significant dose of protein is a definite plus for me, and fueled my strength and endurance at the gym.
I wouldn't personally buy this product line again because I avoid artificial sweeteners for health reasons, but I did genuinely enjoy the taste and convenience.
Overall, I'd rate this product a 5/10 and I don't plan to purchase it again.
Can You Overdose on Fiber?
Before getting to the Fiber One cereal review, we wanted to share this video about whether you can overdose on fiber published by popular health creator "Chubbyemu" that we found really interesting. This isn’t a realistic concern for most consumers but certainly drinking two full liters of fiber is a bad idea:
Fiber One Cereal Ingredient Analysis
The ingredients in Fiber One Original Bran cereal are shown below:
Like Fiber One bars, it’s primarily composed of whole foods.
Whole grain wheat is used as the whole grain and primary fiber source, and its intake is associated with reduced risk of high blood pressure, reduced risk of cardiovascular disease and reduced risk of some types of cancer according to a 2010 medical review.
Corn bran intake is associated with reduced cholesterol levels according to a clinical trial published in the Journal of the American Dietetic Association.
Fiber One cereal contains 18 g of fiber in only 90 calories, which is incredibly high. For this reason, we would recommend Fiber One cereal over Fiber One bars to individuals trying to lose weight.
Like Fiber One bars, there are a few ingredients in this product that we consider questionable from a health perspective.
Sucralose is included, and this artificial sweetener was shown in a clinical trial published in the Nutrition Journal to have a negative impact on insulin levels in healthy adults. We don’t think that cereal needs artificial sweeteners.
Natural flavor is also included which we discussed in the previous ingredient analysis section.
Calcium carbonate and vitamin B6 are part of a synthetic vitamin and mineral blend.
As we documented in our review of another nutrition brand called Keto Chow, a Canadian wellness brand was forced to remove their products from the market because the added vitamins and minerals were causing toxicity in some consumers.
We don’t believe this is likely based on the doses used in Fiber One, but it may be illogical to take added vitamins and minerals without a deficiency.
We do not currently recommend Fiber One Cereal.
Fiber One vs. Popular Fiber-Rich Products
Here's how Fiber One compares to other popular fiber-rich products in terms of healthiness, in our opinion:
Fiber Gummies
These gummies almost always contain refined, added sugar, which is clinically shown to be harmful to human health in excess.
However, the formulations we reviewed in our analysis are still (slightly) healthier than both Fiber One products reviewed in this article.
Winner: Fiber gummies
Benefiber
This fiber powder only contains one ingredient, which is a form of soluble fiber: wheat dextrin.
Soluble fiber supplementation has been clinically shown to improve digestive regularity and lower cholesterol, as we documented in our Benefiber reviews article.
The simple formulation gives Benefiber the edge from a healthiness perspective.
Winner: Benefiber
Metamucil
Brand was recently sued over allegedly containing lead levels 27x the allowable amount.
Also contains unhealthy additives like artificial food dye and artificial flavor.
Winner: Fiber One
Our Clean Gut Health Picks
Manukora MGO 850+ is our top whole food gut health pick.
A 2024 clinical trial reported that manuka honey ingestion "correlates with beneficial modulation of gut microbiota composition."
MBG Organic Fiber Potency+ is our top gut health supplement.
MBG Organic Fiber Potency+ contains 100% soluble fiber, which was described as "one of the most important nutrients for the gut microbiota" in a clinical review published in the Molecules journal.
Both of the products recommended in this section are free of ingredients that we consider to be unhealthy.
Pros and Cons of Fiber One
Pros:
- Effective fiber dose
- Affordable
- Easily accessible
- No cooking required
Cons:
- May contain corn syrup
- May contain artificial sweetener
- Uses natural flavors
- Expensive on Amazon
