Is Bob’s Red Mill Potato Starch Resistant Starch?

Click here for a quick primer on Commercial Potato Starch!

I have heard rumors that Bob’s Red Mill’s customer service is telling people that their potato starch does not contain resistant starch (RS). In October, 2015, this comment appeared on the Bob’s Red Mill website:

Question: Is Tapioca Flour a Starch and would it be considered resistant starch?

Answer: Yes, tapioca flour is a starch, but it is not considered a resistant starch. Our potato starch, however, is considered resistant.

This was a great answer! Spot on. I’m not sure when they changed, but recently, I saw this on an Amazon comment from December, 2016.:

… I emailed Bob’s Red Mill to ask them if this product was actually a resistant starch, and they stated that based on the way they it is processed, it does not remain a resistant starch. You can contact them to verify, but it is not a resistant starch. I went ahead an ordered some WEDO green banana flour.

Hmmm…and on Chris Kresser’s blog, in the comments, also from December, 2016:

I just emailed them too and rec’d a reply this evening… “Thank you for reaching out to us. Our Potato Starch is not a resistant starch. The process of removing the starch component from the potato eliminates any resistant starch benefits. Please feel free to contact me if you have any more questions and have a wonderful day.”

I have three thoughts:

  1. Bob’s does not want to be in the RS/health supplement business, so they are intentionally spreading a falsehood,
  2. Bob’s customer service people do not know that their product is high in RS, and give the wrong information, or
  3. Someone is spreading “fake news” so people use a more expensive (or different) product. Are these “emails” even real?

Please Remember!

When discussing potato starch as a source of type 2 resistant starch (RS2), it must be uncooked. Once heated above 150 degrees, the starch granules swell and burst, becoming “readily digested starch.” Please read my (lengthy) review on resistant starch if you are new to the idea.

Starch Production

I am 100% convinced that Bob’s Red Mill Unmodified Potato Starch, and all other products labeled “unmodified potato starch” are good sources of RS.  Bob’s Red Mill does not make the starch, they buy it from distributors.  All potato starch is made in a similar fashion, easily Googled, and it results in a product that contains uncooked potato starch granules.


Depending on test methods used, the percentage of RS in a sample of potato starch is 50-75%.  In fact, a sachet of potato starch is provided with the test kit for testing RS content in order to calibrate the process.  There is no other native starch with a higher RS content than potato starch, so it makes a good control for the “span” of the test method, known as AOAC2002.02.

For $145, anyone can get some starch tested at Medallion labs, and several other labs that test this sort of thing. I’m surprised Bob’s Red Mill does not regularly test and label, but then they would be selling a supplement and not a cooking ingredient.While I have never sent a sample to be tested, I know some that have…results: Bob’s Red Mill Unmodified Potato Starch contains ~65% RS2.

If anyone needs further convincing, the process to measure RS in various starches was developed in this paper: Measurement of resistant starch by enzymatic digestion in starch and selected plant mater. They sent samples of various starches to 37 different test labs, Table 2 shows the range of results for potato starch (~45-70%, mean 63%). The potato starch used was a standard commercial brand (Avebe Potato Starch, NL).

Interestingly, Bob’s Red Mill told one person that their potato starch was of “Dutch origin,” one website listed it of “Malaysian origin.” My guess is that they buy it from the lowest bidder in huge bulk.  On the open market, this product is traded as “native potato starch” meaning the granules are intact. Otherwise, it’s sold as “modified potato starch.”

Furthermore, UMich did a nice study on RS2 using Bob’s Red Mill Unmodified Potato Starch last summer, had it tested, and found it to be ~50%.  I’m not sure which lab, or if they tried testing it themselves, but at any rate, Bob’s PS worked beautifully in their study.

Variable responses of human microbiomes to dietary supplementation with resistant starch

Participants consumed their habitual diet throughout the study period. During the intervention phase, raw unmodified potato starch (Bob’s Red Mill, Milwaukie, OR) was gradually added to their diet (day 1—12 g, day 2—24 g, day 3—48 g; Fig. 1). This potato starch contains approximately 50 % resistant starch (type 2) by weight…Our data show that dietary supplementation with RS type 2 as unmodified potato starch increases fecal butyrate concentration, but with remarkable inter-individual variation.

Without equivocation, I can give a personal guarantee that the following easily purchased potato starches are good sources of RS2:


However, buying potato starch from any source and using it as a prebiotic RS2 supplement is taking a chance. Until we can buy potato starch, or another resistant starch product that is specifically labeled with it’s RS content, there is always a chance that what you are using is not what you expect.

Therefore, if anyone is worried that Bob or Anthony or any of the other producers are supplying potato starch that is not a high-quality resistant starch, I would suggest this guaranteed source of measured RS2:

I have it on good authority that soon some manufacturers of starch-based prebiotics will soon be launching products labeled with source and content of RS. Stay tuned!

Tim Steele

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9 Comments on “Is Bob’s Red Mill Potato Starch Resistant Starch?”

  1. Jo tB January 11, 2017 at 6:27 am #

    I checked the Dutch version of the Avebe site and they take every care possible to produce a safe product. So if Bob’s Red Mill buys his potato starch from Holland, it will definitely be an excellent product.

    From what I could gather they have production plants all over Europe if not the World.

    3 production locations in Gasselternijveen, Ter Apelkanaal en Malmö (Zweden) have been awarded the Starch Europe Safety Awards.

    Starch Europe is een brancheorganisatie die de belangen van de Europese zetmeelindustrie, zowel binnen als buiten Europa, behartigt. Tot haar leden behoren 24 zetmeelproducerende ondernemingen die samen meer dan 95% van de zetmeelindustrie in de EU vertegenwoordigen. Tot oktober 2014 was Starch Europe bekend onder de naam AAF. Avebe is lid van de brancheorganisatie Starch Europe.

    Starch Europe is a trade association that represents the interests of the European starch industry, both within and outside Europe. Its members include 24 starch-producing companies representing more than 95% of the starch industry in the EU. Until October 2014 Starch Europe was known as the AAF. Avebe is a member of the trade association Starch Europe.

    People in Holland doing the potato resistant starch hack use Honig’s aardappelzetmeel, and someone inquired and found out that Honig purchases its potato starch from Avebe.

    I suppose we could check with Avebe if they regularly get their products tested for resistant starch content.


    • Tim Steele January 11, 2017 at 8:42 am #

      That’s great, Jo tB, thanks! I doubt they are regularly testing the resistant starch content because there is no reason to. I would LOVE to see it, though.


    • Jo tB January 11, 2017 at 9:09 am #

      I just googled the European Starch Association and found the following pages.


      And who the members are:

      A guarantee of quality? I think so.


      • Tim Steele January 11, 2017 at 9:18 am #

        Hartstikkeleuk! I’m working on a blog post for later, but there is also a guarantee of standard used by the pharmaceutical industry. The US Pharmacopeia (USP) allows potato starch to be used as a filler in pills, as long as it conforms to USP standards.

        When you read the standard, they just use commercial grade native potato starch, but test it for things like moisture, mold, color, etc. The standard for USP starch is actually lower than for food-grade starch. And USP does not test for RS, either. see:

        I really need to send a bunch of samples to a test lab, just to ease everyone’s fears.


  2. Diane Kurt May 8, 2017 at 9:31 pm #

    Hi Tim,
    Wondering if you have any information on Japanese lotus root, and its RS properties. It is a starchy root veggie, and much like a potato in texture. Best of all, the Japanese make a salad that is delicious, using raw lotus root, and I’d so much rather go to that than to eating raw potato. Any info you could provide about the RS in uncooked lotus root would be much appreciated. Thanks much! Diane Kurt


    • Tim Steele May 9, 2017 at 7:27 am #

      Tough to say. My feeling is that they are not a good source of RS, but they probably do have other types of fiber just as good. I could only find one RS reference to “lotus root” placing it at ~2% RS, but without the scientific name it could be completely different from Japanese Lotus Root. There are, however, many journal references to lotus root health properties, lots of attention given to the polyphenols found in the roots, for instance.

      Eat up!


  3. Shaun December 16, 2017 at 7:00 pm #

    Just bought your book — and came across this:

    What are your thoughts that starch shouldn’t be supplemented (especially the tumor growth part)?


    • Tim Steele December 16, 2017 at 7:53 pm #

      I was going to tell you to read the comments on that Paleo Mom blog, but I see she has removed them. I was involved in a lengthy discussion there about the problems with the studies she used to illustrate her point, but her bottom-line I agree on: “Raw potato starch may be convenient, but in the long run, it’s less likely to benefit your health than eating resistant-starch-rich whole foods.”Raw potato starch may be convenient, but in the long run, it’s less likely to benefit your health than eating resistant-starch-rich whole foods.”


  4. Jackson May 2, 2018 at 1:17 pm #

    Bob’s web site has a number of responses in their questions and answers section related to potato starch, and claim repeatedly that it does not contain resistant starch. Here is the most recent:

    Dr. Mark Hyman from the Eat Fat Get Thin diet and book, and PBS specials actually recommends your Potato Starch as a resistant starch. Are you sure about your answer on December 18 that it is not a resistant starch?
    Diane C on Jan 6, 2018

    BEST ANSWER: Yes, we are sure our statement is correct and this product is not a resistant starch


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