Resistant Starch Project Update

Time’s almost up! If anyone still wants to donate, and get a first-look at the results, please go to the Indiegogo page or use the PayPal button located here ———>

While I fell far short of my Indiegogo goal of $20,000, I have managed to get over $3000 from 50+ donors. This gets us a lot. I’ll be sending in 18 samples of various starches for RS analysis.

  • Hi-Maize 260 High Amylose Maize Starch (HAMS) from Ingredion, Honeyville, and King Arthur
  • HYLON VII (HAMS) from Ingredion
  • Raw Potato Starch from Bob’s Red Mill (2 samples), Anthony’s, and Barry Farms
  • Green Banana Flour from Zuvii, NuNaturals, De Nieuwe Brand (NL), and Natural Evolution (AU)
  • Dried Plantain – Homemade (by me ) from very green plantains
  • Mung Bean Starch
  • Sweet Potato Starch
  • Kuzu Root Starch
  • Arrowroot Flour
  • Tapioca Starch

In addition, I’m sending 3 duplicate samples of HAMS, RPS, and GBF to another test lab to see if they get a similar result.

Looks like this:


These tests will cost $155 per sample ($3255 for the math-impaired). Once the results are in I’ll send the lab sheets and other documents out to the donors.

I’m really excited to see the results. I’ve heard that mung bean and sweet potato starch are very high in RS, higher than potato starch. I’m also really curious what the RS on all of the potato samples will be. Literature suggests it should be around 60-75%. But no one’s ever tested different batches before.

The reason I’m testing multiple samples of HAMS, RPS, and GPS is because I am confident that these are good sources of RS, but not confident that all brands are created equal. If they all come back at the same levels, I will feel much more confidant to suggest these as supplements.  For instance, green banana flour RS is very dependent on variety, ripeness, and processing methods. Just look at the variations in color between the five samples I’m testing:


The reason for sending just one sample of some is that I am not all that confidant in them.  If any come back very low, we can rule out recommending it.  If any come back very high, we could recommend further testing to see if there is standardization between batches. I think this methodology gets us the most for our money.

Challenges Encountered

These results should be very useful to researchers and supplement manufacturers as interest in prebiotic fibers and resistant starch grows. I hope to be able to write this up in a nice report for publication in a peer-reviewed journal. Perhaps it will spark some interest and researchers can do more testing, ie. heavy metals, pesticides, total fiber, minerals, etc… Would be nice to see, but very expensive!


My first challenge was in dealing with Ingredion, the makers of Hi-Maize. I contacted their POC for research, and asked some basic questions about high amylose maize starch and showed them my Indiegogo project (hoping for a donation). Their reply:

We cannot be of assistance with your project.

I assume they are not eager to aid in any research that will compare their flagship RS product, Hi-Maize, with other sources of RS. I was able to obtain samples of two Ingredion high amylose maize starch products from a distributor, Essex Grain, who kindly sent me a sample of Hi-Maize 260 and HYLON VII, and also two commercially procured samples from King Arthur Flour and Honeyville.


Another challenge was getting funding support from researchers. I contacted dozens of research centers who conduct clinical trials using resistant starch. These requests generated lots of email conversations, but no funding. They all had similar stories, ending in:

“We’d love to help, but we are BROKE!”

However, when Indiegogo donations started coming in, I saw several from people with “.edu” email addresses. So hopefully the results will help academia.

Testing Labs

It turns out there are not very many commercial labs that perform resistant starch testing. I found two. However, when I discussed my project with one of them, I was given these instructions by their legal team:

– May not name [our lab] as the third party testing lab

– Must agree to blind the samples (no Brand name)

Apparently this project creates a conflict of interest. These two test labs also test the products of food and supplement manufacturers.  I can see their point, so I made the necessary change in that all of the starch I will send for sampling will not be labeled with a brand name, only starch type.


While I fell far short of my intended target of $20,000, the money raised will definitely help to answer some very important questions about the RS content of the various starches that I have been recommending. Any surprises learned will be shared with all, immediately.

Blog Readers

THANK-YOU!  Many of the regulars here at Potatohack and VeggiePharm came out in droves to support this project. I had hoped to fund this project with donations from “big research,” but when things looked bleak, you guys came through. I can’t begin to express my gratitude. And also to the couple of you that sent me samples of starches I could not obtain locally.

Supplement/Food Companies

Also, a big thanks to the makers of Zuvii Banana Flour, Gut Garden, Elixa, and International Agriculture Group for making generous donations. I hope that the results helps you all to make better decisions in the future and leads to new (much needed) prebiotic supplements and food ingredients.

Thanks for all your support!

Tim Steele

23 thoughts on “Resistant Starch Project Update

  1. Hi Tim,

    Just wanted to clarify which product you’ll be testing from Natural Evolution: their Green Banana Flour, or their Green Banana Resistant Starch?

    Excited to see the results!


  2. Tim,
    I make yogurt at home on a regular basis. Last batch I made, I mixed some hi-maize powder in the milk before I added the culture. The yogurt turned out much thicker in consistency and better overall than without hi-maize. The idea behind mixing RS in yogurt making process is that I’d be getting pro and pre-biotics at the same time. But now I am not so sure as I started to think more about it.

    We generally want the RS to reach distal portions of our colon intact so the good bugs can feast on it. If I am adding it to the yogurt, which sits in the fridge for up to a week with live culture in it, doesn’t the RS get “eaten” up by the yogurt before it has a chance to reach the colon where the good bugs can eat it? Do you think it defeats the purpose to do it this way?

    I will probably continue to mix hi-maize with yogurt but want to know what your thoughts are.



    1. Good question. And I have a good answer! The RS properties of Hi-Maize are mainly undisturbed when mixed into yogurt. I think this is because yogurt is kept cold and there are not enough co-factors to allow the bacteria to wildly ferment sugars and starches in the yogurt. Supposedly, rather than fermenting the RS granules, the bacteria will attach themselves to the granules and begin eating when the conditions are right.

      Here’s a great paper from 2015 where they looked at adding Hi-Maize to yogurt. Figure 1 shows a microscope picture of the intact granules, and even found that the Hi-Maize enriched yogurt could be pasteurized with no effect on the RS.

      I suspect we will soon see Hi-Maize enriched yogurt on the store shelves, but as you’ve noted, it’s very easy to make at home. Adding raw starch to yogurt is my preferred way of eating it as well.


      1. Fantastic!!! Thank you for the citation as well.

        Yes, it is very easy to make yogurt at home. You don’t need any fancy yogurt makers as long as you are ok with not inconsistent but acceptable results from batch to batch. You will need time and patience, that’s all! But you can save a ton of money if you eat yogurt regularly.
        Buy some good culture and you can reuse your own yogurt as culture for several batches…I usually go 4 to 6 months before I need to open a new culture packet.


      2. Tim, I think you may have missed the part where “T-nat” mentions: “before I added the culture”. It’s not about mixing Hi-Maize into yoghurt and then kept cool, but rather: adding Hi-Maize to milk+culture and then letting it ferment (in a yoghurt machine for many hours, at 30+ degrees C). I’ve seen this technique mentioned more often by home yoghurt-makers (usually a teaspoon of inuline). I think “T-nat” is right in his/her assessment that the Hi-Maize will be used as a substrate for the yoghurt culture bacteria *during* the fermentation process, and that there will be none of it left after the yoghurt has fermented. My belief (but have no proof), is that adding a prebiotic before starting the yoghurt fermentation process is helping the bacteria go wild (and multiply more rapidly), not only on the lactose in the milk, but on the added substrate.


  3. The good news keeps coming in! Congrats!

    Have you thought about approaching the potato growers associations about maybe a Google ad when somebody searches about potatoes and health and/or weight loss? Or maybe a New York Times or WSJ Review ad? Maybe I’m unique, but those are probably the only places I look at ads because I’m always searching for books. I did a Google search on “potato growers associations” and it seems there are many, at least 10 I think. Your book fits nicely with their core job. “Don’t eat more potatoes. Eat only potatoes!” I get royalties if you use that lol. It might get even more notice if it’s paired with Jillette, dunno.


  4. This is a really great project, and I can’t wait to see the results (is it too late to donate?). There’s a tiny thing that threw me off in this post though: I’m pretty confident that “confidant” should have been spelled “confident” in the context it’s used 🙂


  5. I see you have added Sweet Potato Starch to the repertoire along with Mung Bean flour. I hadn’t heard of Sweet Potato starch so did a quick Google search and lo and behold my favourite Asian toko has Sweet Potato starch from Taiwan. I will add that to my testing regime. I had tried Mung Bean flour in the past, so will try that one as well.


    1. Jo tB – I am just compiling the results, it appears that sweet potato starch, tapioca, and arrowroot are very low in RS (less than 4%). Mung bean has 7%, and kuzu root starch has 22%. Perhaps kuzu root would be worth using, but it’s pretty hard to find. Also called kudzu root or Japanese arrowroot. See on Amazon:


  6. Given the potato-hack thing, some RS tests on cooked potatoes would be even more interesting. Different varieties of potatoes, and just-cooked, warm potatoes vs cooked and then chilled-for-a-day potatoes. I’m new to this site, and have not read this book so forgive me if you already have this data…


      1. Hey, thanks, that just the sort of thing I was looking for. Though I was hoping to find the general difference between waxy and starchy potatoes, and it looks to me like they only used waxy ones in that study. I know starchy (aka baking potatoes, usually rough-skinned) generally have more starch, but I don’t know if that also means more RS or how they react to cooling comparatively.


        1. The difference between a waxy and starchy potato is only about 5% total starch content, 16% vs 21%. The starch of both types is very similar. Except for pure scientific curiosity, there is no reason to choose one potato over another for it’s RS content when cooked.

          I like to choose from a variety of cooking potatoes, the colored ones always have more flavonols and polypehnols, making them as healthy as blueberries in some instances with the purple-fleshed potatoes.

          Labs have a very hard time calculating the actual RS3 in cooked/cooled foods/potatoes because the testing itself causes further retrogradation as the sample is heated and cooled to perform the test.


          1. Thanks again. I didn’t want to assume the starch was the same, as it certainly behaves differently when cooking, as far as the texture goes. Personally I far prefer starchy potatoes from a cooking / eating standpoint. I have very little use for waxy potatoes, so I’m happy to now know that they have no RS disadvantage.

            Interesting, that about the lab testing quandary!

            BTW, that 5% difference in terms of the 100% that includes non-starch sounds trivial when presented that way, but when looked at in terms of the amount of starch, it is close to a third more starch, which is not insignificant.


  7. Is there a webpage with the test results? I was not surprised about sweet potatoes, but was surprised by mung beans. Also, has anyone tried resistant wheat starch 75? It is supposed to be about 75% resistant starch (so higher than Hi Maize). I’ve ordered some and will give it a try to see how I respond to it. I’ve been trying to use a variety of different resistant starch sources to give my bacteria more to eat from, and to try to reduce some of the potassium levels from potatoes and bananas because I might be getting a bit too much potassium which can lead to problems. I’ve also been eating a lot of Great Northern Beans– cooked and then cooled– because they are a naturally high source of resistant starch.


  8. According to this reference:

    Sweet potato microstructure, starch digestion, and glycemicindex
    Sunantha Ketnawa, Lovedeep Kaur, Yukiharu Ogawa, Jaspreet Singh

    “Native Raw Sweet Potato Starch” has higher resistance to the in vitro digestion process (RS 84.9%88.0%) followed by retrograded (RS 14.3% 22.4%) and freshly gelatinized (RS 10.2%14.7%) starches


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s