Fiber One Review: Healthy or Processed Garbage?

Fiber One Review: Healthy or Processed Garbage?

| |
| |

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 questionable additive ingredients? Do they provide an effective fiber dose? And how do real users rate and describe the taste and effects of Fiber One?

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 based on medical studies: Fiber One bars and Fiber One cereal. We’ll give our take on whether these products are healthy and contain enough fiber.

We’ll also feature real, unsponsored Fiber One user reviews and explain where to buy Fiber One for the best price.

Fiber One Bars Ingredient Analysis

Fiber One Bars ingredients

The ingredients in Fiber One Caramel Nut protein bar are shown above.

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 the 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.

A YouTube video from a creator named Alice Chan-Harris has a taste test of every Fiber One bar:

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:

We Tried Fiber One – Our Take

Fiber One UGC

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.

I'd rate this product a 5/10.

Fiber One Cereal Ingredient Analysis

Fiber One cereal ingredients

The ingredients in Fiber One Original Bran cereal are shown above.

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.

There are also a number of added vitamins and minerals including calcium carbonate and vitamin B6. 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 in 2022 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.

A YouTube channel called “Cereal Time With Clay” reviewed its taste:

Where to Get the Best Price

Fiber One products are sold at a variety of retailers. Here’s the price breakdown for the two products we reviewed in this article, accurate as of the time of updating this article:

Fiber One Protein Bar (10-pack)

Fiber One Cereal

Amazon has the best prices on Fiber One products by far when factoring in shipping fees.

How to Make Healthy Granola Bars at Home

A YouTube creator named “Well Plated” has a video showing you how to make healthy, high-fiber granola bars at home:

Our Clean Gut Health Picks

MBG Organic Fiber Potency+ is our top fiber pick.

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.

Ritual Synbiotic+ is our top value probiotic pick.

It contains prebiotics, probiotics and postbiotics, and costs under $1.50 per serving at the time of updating this article.

Probiotics "can improve in the immune, systems in healthy adults" according to a 2019 medical review.

VSL#3 is our top premium probiotic pick.

This probiotic supplement has been studied in 25 clinical trials, and a 2020 meta-study on VSL#3 concluded the following:

"...many studies demonstrated that VSL#3 has a beneficial effect on obesity and diabetes, allergic diseases, nervous systemic diseases, AS, bone diseases, and female reproductive systemic diseases."

All of the products recommended in this section are entirely free of ingredients that we consider to be unhealthy.

Pros and Cons of Fiber One

Here are the pros and cons of Fiber One in our opinion:


  • Effective fiber dose
  • Affordable
  • Easily accessible
  • No cooking required


  • May contain corn syrup
  • May contain artificial sweetener
  • Uses natural flavors
  • Expensive on Amazon
Stay up-to-date on our research reviews


Fiber One products contain an impressive amount of fiber per serving, and we believe this brand may be useful for people trying to lose weight, because high intake of fiber is associated with weight loss in clinical trials.

We do not currently recommend any Fiber One products because both of the products we reviewed contained questionable additive ingredients including flavoring agents and sweeteners.

There are ways to make healthy, high-fiber granola bars at home, and there are fiber products on the market that are free of questionable additives.

For consumers intent on purchasing from Fiber One, we recommend doing so on Walmart where their products appear to be the cheapest.