Quest bars using soluble corn fiber

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Quest Nutrition started using soluble corn fibre instead of isomalto-oligosaccharides (let’s call it IMO from now on). This may have been due to:

  • a lawsuit, for not meeting label claims, misstating carb and fiber content;
  • quest bars/IMO raises blood sugar levels on people that have tested it;
  • Using IMO makes Quest Bars rock solid (microwave it for 10 seconds).

The lawsuit

The claim is that Quest’s fiber content is overstated from 50% to 10 fold the actual amount; and that calories are understated by at least 20%.

Claim against quest nutrition
Highlighted areas of claim

I recommend you read this article as it explains the lawsuit very well, then come back here to read the rest.

The lawsuit was dropped in late 20131.

In late 2014 Quest switched from IMO to soluble corn fibre, along with a change in other ingredients. S’Mores was the first Quest Bar using soluble corn fibre.

In a blog post, Quest Nutrition states that the reason for an ingredient change was because they “are obsessed with being on the cutting edge of traditional science” and that some ingredients weren’t allowed in all places, “for instance Lo Han Guo, a plant-based sweetener, isn’t allowed in Europe”. At nowhere in the article they mention soluble corn fibre specifically, though.

The switch to soluble corn fibre

They may have switched to soluble corn fibre (SCF) due to:

  • the IMO controversy
  • SCF has the benefit of extending shelf life
  • IMO syrup in the EU showed that it raises blood sugar levels almost as fast as glucose. As a result the use of IMO in the EU in food products, must by law, carry a “not suitable for diabetics” warning.3

Soluble corn fibre can also be called “corn syrup” or “corn syrup solids”, according to the manufacturer4. That means this is syrup, but under a different guise. Also note that this is genetically modified (GMO).

That’s why the folks at Reflex Nutrition in their R-Bars decided not to use IMO nor soluble corn fibre (used by Quest now), and use Soluble Gluco Fibre instead. Soluble gluco fibre is manufactured by the same company, but it’s a different product, which supposedly is non-GMO and doesn’t the potential drawbacks of soluble corn fiber. This ingredient gives the Reflex R-Bar a unique, soft texture and boosts fibre content whilst maintaining a low sugar value.

The calorie debate

But whether you use IMO, soluble corn fibre or any other type of prebiotic fibre, there is the sometimes misundertstood issue of dietary fibre, which is something that can affect not just quest bars but all protein bars that don’t specify their net/active carbs from dietary fibre.

Because this affects calorie count. Take a look at this.

Mint Chocolate Chunk
Mint Chocolate Chunk - Box of 12

20g Protein

Mint Chocolate Chunk
INGREDIENTS: Protein Blend (Milk Protein Isolate, Whey Protein Isolate), Soluble Corn Fiber (Prebiotic Fiber), Water, Almonds, Cocoa Butter, Cocoa (Processed with Alkali), Natural Flavors, Erythritol, Palm Oil, Dextrin, Sea Salt, Sunflower Lecithin, Sucralose, Color (Fruit Juice, Turmeric), Coconut Oil, Xanthan Gum, Baking Soda, Peppermint Oil, Steviol Glycosides (Stevia).
Nutrition Facts
Serving Size 1 (60g)
Calories 190
Calories from Fat 80
*Percent Daily Values are based on a 2,000 calorie diet

%Daily Value*
Total Fat 9g
Saturated Fat 4g
Trans Fat 0g
Cholesterol 5mg
Sodium 210mg
Vitamin A 2%
Vitamin C 0%
Magnesium 2%
Phosphorus 10%

%Daily Value*
Potassium 125mg
Total Carbohydrate 21g
Dietary Fiber 15g
Sugars <1g
Erythritol 2g
Protein 20g
Calcium 15%
Iron 4%

CONTAINS: Almonds, Coconut and Milk-Derived Ingredients.
Only 4g net carbs (and they’re all from nuts – not sugar).
The only true low carb bar on the market.
*Isomalto-Oligosaccharides are Prebiotic Fibers derived from plant sources.

The total calorie count adds up more than listed.

Calories = (20g Protein * 4) + (21g Carbohydrates * 4) + (9g Fat * 9)

20*4 + 21*4 + 9*9 = 245 calories

The calories on the label are 190. This difference is explained by the dietary fiber. Carbs that count towards calories are lower than total carbs listed due to insoluble fibre not being digested by the body, and so it amounts to zero calories. Soluble fibre does have calories, but not 4 calories per gram.

In the macro list of the Quest bar, instead of counting 21g of carbs, they are counting 7.25. To reach this number, they are roughly subtracting “Dietary Fiber” 15g from “Total Carbohydrate 21g” in the label. 21g – 15g = 6g, but it’s close enough. The missing 1.25 might be some rounding/down we’re not aware.

20*4 + 7.25*4 + 9*9 = 190 calories

Quest calculates the total carbs minus the carbs from fibre, the “active carbs“, which can also be referred to as “net carbs“. If the fibre content goes down, the active/net carbs go up, which is something low carb dieters need to take into account.

Quest bar banana nut muffin nutrition facts

ConsumerLabs tests

In midst of this controversy, ConsumerLab, an independent testing agency, tested the nutritionals of Quest’s Banana Nut Muffin bar (without being prompted) and concluded that both fibre and calories matched the label content2.

The lab did not test for IMO specifically, as according to Quest’s official communication about this controversy, “IMOs require a unique testing protocol specifically designed to accurately detect IMO.”

Protein bars

Other bars using IMO

After the success of Quest Bars, other companies began using IMO as an ingredient.

Bars like Muscle Pharm’s candy-like Combat Crunch, the tasty Oh Yeah Victory Bars (and the new Oh Yeah Low Carb Bars), the Paleo Protein bars, EnergyFirst’s healthy Permalean bar and possibly a few others.

Then there are the sugar alchools. These are a class of reduced-calorie sweeteners that substitute sugar and have minimal impact on blood sugar. Some people tolerate it well, but in others it may result in major laxative effects and goastrointestinal discomfort (gas, bloating). You check for sugar alcohols in ingredients that end in “-ol” (sorbitol, maltitol, xylitol, or erythritol).

Cookies & Cream and S'Mores

Last quest bar using IMO

The last quest bar using IMO was Cookies & Cream. The S’Mores (their next flavour) started using soluble corn fibre. And from there on out, others followed, like the Mint Chocolate Chunk, released April 2015.



Reflex R-Bar (soluble gluco fibre, not corn)
The R-Bar – if you’re in the UK (Predator Nutrition)
The R-Bar – if you’re in the UK (Amazon)
The R-Bar – if you’re in the UK (Affordable Supplements)
The R-Bar – if you’re in the UK (Discount Supplements)

Reflex R-Bar Flapjack (soluble gluco fibre)
The R-Bar Flapjack – if you’re in the UK (Amazon)
The R-Bar Flapjack – if you’re in the UK (Discount Supplements)

ISS Oh Yeah Victory bars (IMO)
Oh Yeah Victory Bars – if you’re in the UK (Predator Nutrition)
Oh Yeah Victory Bars – if you’re in the UK (Amazon)
Oh Yeah Victory Bars – if you’re in the US/world (

ISS Oh Yeah Low carb bars (IMO and maltitol)
Oh Yeah Low Carb Bars – if you’re in the UK (Amazon UK)

Muscle Pharm Combat Crunch bars (IMO)
Combat Crunch bars – if you’re in the UK (Discount Supplements)
Combat Crunch bars – if you’re in the US/world (

Paleo Protein bars (IMO)
Paleo Protein bars if you’re in the US

EnergyFirst Permalean bars (IMO)
Permalean gourmet bar – only ship to a select countries


Combat Crunch all flavours
Combat Crunch Chocolate Chip Cookie Dough review
Reflex R-Bar Cookies and Cream

Related articles on the web

The Quest Bar lawsuit–and why science shows it’s bogus
Makers Of Quest Bars Sued Over Mislabeling; Allegedly Overstated Fiber By More Than 750%
Quest Bar Mislabeling Lawsuit
Isomalto-Oligosaccharides and Protein Diet Bars

  1. Quest blog — fiber count lawsuit dropped (blog post) go back
  2. ConsumerLab — 20 tests of Nutrition Bars (including Quest bars) go back
  3. Advisory Committee on Novel Foods and Processes (ACNFP) Isomalto-oligosaccharide. EC No. 103 go back
  4. PROMITOR® — Soluble Corn Fiber 70 go back

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About jon

Jon is a self-confessed protein bar addict that loves writing about protein bars, snacks and desserts. He is a former marketer turned into a blogger. Oh, and he loves writing in 3rd person.


  1. Josie

    Hey, I’ve just been looking into this

    The R-bars ingredients are discussed on their blog here:

    And they link to a site on promitor as their “soluble gluco fibre”

    A quick read of their Infographic PDF states that “Labelling as ‘soluble gluco fibre’ in Europe, and ‘soluble corn fiber’ in most other parts of the world” so actually to me they are the same thing, it’s just labelling regulation differences that mean they look different….

    1. Josie

      Ok a little more digging shows that the EU version is made with non-GMO corn but apart from that I think it’s identical. Also they state that it contacts 1.2-2 cals per gram which might help make the nutrition numbers add up :)

      “Based on a dietary fibre already successful in North and South America, PROMITOR™ Soluble Gluco Fibre was developed with non-GMO maize for the European and other GM-sensitive markets.”

  2. Vanessa

    As a former quest fan I come from a diabetic family and used to eat 3 quest bars a day, and lost weight form it on their old formula. CnC was my fav.

    I did not experience sugar spikes. So I think the data are over stated and not entirely representative of the entire world population. I for one love sweets, but eat very healthy and whenever I’d eat a Q.B. to curb my cravings I’d have no such spike as a type 2 diabetic.

    I also am allergic to gluten, and corn, and the old formula does not give me any trouble whatsoever. I accidently ate the new formula and almost went to the ER because of the amount of pain and sickness I was in for 3 days.

    Quest recent posted on the FB that the IMO blend had corn in it, yet that did not give me trouble. IMO never has. So I’m wondering if it’s in such a small amount my body doesn’t recognize it, or they really are just saying that because of the 1000’s of complaints about grain and corn allergies and how eating the new formula unknowing made 1000’s of people ill.

    Literally. And not just because of hte rock hard texture and horrid taste. I don’t feel the new formula combats the texture issue at all and I for one never tried smores or the mint bar so I wasn’t aware that was out about six months before the total switch.

    I just know I always ate CnC and sometimes cinnamon roll and cookie dough. Overall the reps I’ve spoken to one minute claim there is no corn in it and somehow they can remove the DNA aka protein that causes allergic reactions, the next minute the reps are appologizes people are allergic to corn and can no longer eat their bars.

    THEN the next minute they are claiming corn has always been in their fiber blends! All ingredient information concerning any allergens must be disclosed to the public and when they bought the IMO syrup they would have know from the get go and been able to respond right away unless it was a trade secret, in which case those are usually devoid of all common allergens such as soy, gluten, corn and nuts (although not always tree nuts).

    I did some research to figure out if i could make my own. So while a company may say we cannot tell you the exact list, we can tell you what it doesn’t contain and that it’s gmo free and 100% natural with no synthetic alterations besides the overall process of making IMO which is synthetic in and of itself since it’s a manmade blend of fibers. Anywho, this case was dropped and the fiber counts really depends on what diet you are on.

    If you are only counting net carbs to eat a 150g diet and lose weight through healthy eating and exercise, net carb counts are what you want. If you are doing serious dieting for say a competition, then maybe 50-100grams (btw for a woman—men can go much lower more quickly more safely), then you want to count all carbs. SO i feel this case wasn’t 100% accurate.

    Regardless I refuse to support quest any more as they refuse to address my questions and blocked me on FB after I voiced my reaction to the bars, and listed some alternative bar recommendations and asked them nicely to respond to my post with all of my questions in it, which ultimately would have saved htem time since 1000’s of FB posters want to knwo the same things as well.

    They are acting very fishy and the CEO couldn’t care less that me and a few other people want to get a case together, and have made it very known. Ugh. I hate it when companies get bought out by multibillion companies selling GMO-corn fiber (that’s the most recent roomer on the quest FB page).


    1. Hello Vanessa, I’m sorry to hear about your problems.

      You feel like you’ve been cheated by Quest Nutrition by not being totally open about their ingredients.

      It’s possible that their previous binding agent, Isomaltooligosaccharide (IMO for shorts) might not have posed problems to you.

      IMO was however causing problems to some people (like insulin spikes), and then there was the issue with the bars being too thick and chewy.

      Quest may have changed to soluble corn fiber due to that, and another important thing: shelf life. Soluble corn fibre pushes expiration date further.

      It’s possible that even small amounts of corn, if you’re allergic to it, can cause you problems.

      If you’re not into Quest anymore, I suggest you have a look at the R-Bar, by Reflex Nutrition. It’s one of the best, and safe protein bars. They use soluble gluco fibre, instead of soluble corn fibre. Have a look at the R-bar Cookies and Cream.

      Have you any problems with Soy? If not, I also suggest Grenade’s Carb Killa Cookies and Cream.

  3. Guest

    I’m a diabetic and have researched soluble fibers and sugar alcohols and how they affect blood sugar levels.

    Soluble Fiber:

    You do digest soluble fiber, although a more accurate term would be that you ferment it. Most things (especially carbs) are adsorbed in your small intestines within 30 minutes of your last bite. Soluble fiber isn’t adsorbed and instead makes it to your large intestines were your gut bacteria breaks it down. This (slow) breakdown creates short chain fatty acids and sugars, over several hours. The net calories for you is about 1 per gram. This is where diabetics get into trouble and get confused.

    Most people (diabetic or not) actually have a better blood glucose response adsorbing sugars and fatty acids slowly over 4 to 12 hours than all at once. If you eat a lot of soluble fiber the effect is like eating a small candy every half our over many hours, whereas if you had eaten all the candies at one time you would get a massive spike. Some diabetics, with very poor glucose control, get spikes from soluble fiber / IMO while most do not. This slow adsorption over a long time can also greatly complicate insulin dosage. Diabetics with the worst glucose control are also the most likely to use insulin.

    For most people soluble fiber is good for you and your glucose control. It keeps you regular, it keeps your beneficial gut bacteria happy, and it reduces the risk of colon cancer. Although the best, cheapest, and easiest source of soluble fiber is fruits and vegetables.

    Sugar Alcohols:

    Sugar Alcohols are a big con. They differ from regular monoglycerides by a single functional group. So your body has to digest them in a different way but they are EVERY BIT AS DAMAGING to your body if they get into your blood. In fact most non-glucose sugars and sugar alcohols are many times MORE damaging to your nerves and kidneys. This is why your liver immediately digests fructose and galactose very quickly. 20 extra mg/dl of fructose is equivalent to over 200 extra mg/dl of glucose. This also explains why low level and slowly adsorbed fructose from fruit is harmless but massive fructose, all at once, from table sugar (sucrose) and HFCS overwhelms your liver’s ability to cope, and damages your entire body.

    Our bodies are very good a digesting galactose and fructose but are not evolved (or designed) to digest sugar alcohols, so the ones that get into your blood stay there for HOURS until your kidneys excrete them. The most notorious adsorbed sugar alcohol is Erythritol. The big con here is that Erythritol in your blood will not show up on a glucose meter.

    At the other end of the spectrum are sugar alcohols that are NOT adsorbed into the blood. The most common of these are sorbitol and malitol. They have zero calories and zero effect on blood glucose. Like (digestible) soluble fiber they feed your gut bacteria but since they are analogous to simple sugars the bacteria gets 99% of the calories and you get none. That’s ok if you are eating one or two grams in an apple but when you eat a lot all at once it can cause severe gastrointestinal ‘distress’. Google “sugar free gummy + review” to get an idea.

    About Quest Protein Bars:

    This is the third iteration of Quest bars (that I know of). About 3 years ago they didn’t have (much) Erythritol, then they did, now they don’t again. When they switched to more Erythritol a few years ago I noticed because I have an allergic response to high blood sugar (lucky me, really). I would eat a Quest Bar and start to itch like my blood sugar was above 150 mg/dl, when my meter was saying 110. I noticed that some flavors had as much as 20 grams of Erythritol while others had just a little. Right now I’m looking at Chocolate Brownie (1 g) and Coconut Cashew (4g) which is acceptable, although I would prefer none or sorbitol.

    As far as the switch from IMO to soluble corn fiber I’ve noticed no difference in my blood glucose (or taste).

    I don’t really care about GMO which is ironic because I am most definitely allergic to gluten when I wasn’t just 10 years ago. I’ve yet to figure out if the problem with gluten is the new/’alien’ Dwarf Wheat, the genetic modification they did to it, or the fact that they now DROWN it in glyphosphate (I’m leaning towards #3). Thanks for making wheat poison Monsanto! No really thanks. Almost everything made with wheat is ultra processed high carb junk.

    I hope this helps my fellow diabetics (and everyone else) out there.

    1. Guest


      Glucose, Fructose, and Galactose are monoSACCHARIDES not monoGLYCERIDES. Almost all sugars, carbs, and starches are made of these three simple sugars.

      Also different sugar alcohols metabolize in different ways, so they are not all terrible. But if it is adsorbed and metabolized then it DOES contribute calories. Erythritol is the only one (that I know of) that 100% enters the bloodstream and then is NOT metabolized. It just sits in your blood until it is (slowly) excreted by your kidneys.

      You would have to look up each sugar alcohol individually to see how well it adsorbs and how it metabolizes (into glucose, into triglyceride, or excreted). I noticed that some of the other bars you reviewed have different sugar alcohols like maltitol or xylitol.

      FYI, ZYLITOL IS DEADLY TO DOGS, so be careful with that one.

      -Thanks for the interesting blog!


      1. You’re welcome, and thanks for adding that.

        What protein bars do you usually have these days?

    2. Margie

      Thanks for posting this. I’ve been wandering the web ever since I finally realized that
      erythritol has been causing me some very nasty symptoms over the last year or more. It never dawned on me, because this sweetener is generally considered safe. I am a big consumer of Quest bars, but it took me awhile to associate them with my problems. Even then I thought I just needed to limit them. Then I used Swerve confectioners sweetener, which is erythritol, to make a single serving of a chocolate treat and got very ill. So I guess I’m not off Quest for good, although I’m not sure what I’ll do with those boxes of bars. I have diabetes in my family so I don’t like the idea that IMO causes blood sugar spikes. Have you used Lo Han Guo and what is your experience with this?


      1. Marge, I haven’t used Lo Han Guo. Is it supposed to lower blood sugar?

        One thing that works well for that is cinnamon. You can start using it as a spice or as capsules. There is even a cinnamon + biotin + chromium combo from Natrol that I use myself (and told my father to take it as well) as it lowers blood sugar.

  4. JJ

    So how can these be considered sugar-free if they essentially contain corn syrup??

    PS. I’m another one Quest blocked on FB after calling them out on a scam they were running (data collection, essentially) where they claimed they’d send you two free bars–took your contact info–and then never sent a thing.


    1. It must be tough not being able to voice our opinion when someone doesnt want to hear from you.

      Quest bars do have sugar, although at just a couple of grams in the ingredients.

      Corn soluble fibre is what they are using as a binding agent for the bars. They used to use IMO ( isomalto-oligosaccharides), but they switched to soluble corn fibre due to some people protests and the bad rep they got with the lawsuit.

      Have you had issues with the bars itself, healtwhise? Or do you feel Quest isn’t being upfront with people?


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