I asked Dr. Amy Nett, MD, to contribute this guest post. Amy initially completed her medical training in radiology at Stanford University Hospital, but wanted to work more directly with patients, helping them to prevent and reverse chronic disease and truly transform their health. Combined with her passion for nutrition she decided to pursue a career in Functional Medicine. You’ll be hearing more from Amy in the future!
Over the past several years there has been an exponential increase in the number of studies linking imbalances or disturbances of the gut microbiota to a wide range of diseases including obesity, inflammatory bowel diseases, depression and anxiety (1,2,3,4,5). One of the best ways to establish and support a healthy gut microbiome is by providing the right “foods” for your gut bacteria. These “foods” are called prebiotics.
Why you should add resistant starch to your diet. #healthydiet #resistantstarch #gutdisgestion
Prebiotics are indigestible carbohydrates, or at least indigestible to us, that reach the colon intact and selectively feed many strains of beneficial bacteria. Prebiotics are generally classified into three different types: non-starch polysaccharides (such as inulin and fructooligosaccharide), soluble fiber (including psyllium husk and acacia fibers), and resistant starch (RS). Each of these types of prebiotics feeds different species of gut bacteria, but among these, RS is emerging as uniquely beneficial.
The distinctive benefits of RS seem to be unequivocally recognized, even amongst advocates of a low carbohydrate diet.
What Is Resistant Starch?
Resistant starch is a type of starch that is not digested in the stomach or small intestine, reaching the colon intact. Thus, it “resists” digestion. This explains why we do not see spikes in either blood glucose or insulin after eating RS, and why we do not obtain significant calories from RS.
There are four types of resistant starch:
RS Type 1: Starch is physically inaccessible, bound within the fibrous cell walls of plants. This is found in grains, seeds, and legumes.
RS Type 2: Starch with a high amylose content, which is indigestible in the raw state. This is found in potatoes, green (unripe) bananas, and plantains. Cooking these foods causes changes in the starch making it digestible to us, and removing the resistant starch.
RS Type 3: Also called retrograde RS since this type of RS forms after Type 1 or Type 2 RS is cooked and then cooled. These cooked and cooled foods can be reheated at low temperatures, less than 130 degrees and maintain the benefits of RS (6). Heating at higher temperatures will again convert the starch into a form that is digestible to us rather than “feeding” our gut bacteria. Examples include cooked and cooled parboiled rice, cooked and cooled potatoes, and cooked and cooled properly prepared (soaked or sprouted) legumes.
RS Type 4: This is a synthetic form of RS that I’m including for completeness, but would not recommend. A common example is “hi-maize resistant starch.”
Once RS reaches the large intestine, bacteria attach to and digest, or ferment, the starch. This is when we receive the benefits of RS.
How Resistant Starch Impacts Our Health
The normal human gut has hundreds of bacterial species, some good and some not so good. The overall number and relative quantity of each type has a profound effect on our health and well being. Resistant starch selectively stimulates the good bacteria in our intestines, helping to maintain a healthy balance of bacteria (7).
These good bacteria “feed” on RS and produce short chain fatty acids (through fermentation), the most significant of which are acetate, butyrate, and propionate. Of these three short chain fatty acids (SCFA), butyrate is of particular importance due to its beneficial effects on the colon and overall health, and RS appears to increase butyrate production more when compared with other soluble fibers (8).
Butyrate is the preferred energy source of the cells lining the colon, and it also plays a number of roles in increasing metabolism, decreasing inflammation and improving stress resistance, as described in more detail below and previously in this great article by Stephan Guyenet.
Resistant Starch Helps to Lower Blood Glucose Levels and Improve Insulin Sensitivity
Insulin resistance and chronically elevated blood glucose are associated with a host of chronic diseases, including metabolic syndrome. Several studies have shown that RS may improve insulin sensitivity, and decrease blood glucose levels in response to meals (10, 11, 12). In one study, consumption of 15 and 30 grams per day of resistant starch showed improved insulin sensitivity in overweight and obese men, equivalent to the improvement that would be expected with weight loss equal to approximately 10% of body weight (13).
Further, RS has been shown to exert a “second meal effect.” This means that not only does RS beneficially decrease the blood glucose response at the time it’s consumed, but, somewhat surprisingly, blood glucose and insulin levels also rise less than would otherwise be expected with the subsequent meal (14).
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Why the Popular Press Has Touted Resistant Starch as a “Weight Loss Wonder Food”
RS appears to have several beneficial effects that may contribute to weight loss, including decreased blood insulin spikes after meals (as discussed above), decreased appetite, and decreased fat storage in fat cells. There may also be preservation of lean body mass, though further studies in humans are needed to confirm if there is a significant impact in overall body weight (15).
Further, several studies have shown alterations in the gut microbiome in association with obesity, which subsequently change towards that seen in lean individuals with weight loss (16, 17). For example, one study demonstrated that the relative composition of the gut microbiota of two predominate beneficial bacteria, Bacteroidetes and Firmicutes, varied considerably in association with body composition.
Specifically, obese individuals often have a higher proportion of Firmicutes to Bacteroidetes, which may be reversed with weight loss, gastric bypass surgery, or treatment with prebiotics (3). However, not all studies confirm a significant or measurable change in the composition of the microbiome in obese compared to lean individuals, and further studies are needed (18, 19).
Butyrate Plays an Important Role in Gut Health and Decreasing Inflammation in the Gut and Other Tissues
As mentioned above, RS intake allows for increased production of butyrate by our gut microbes. Butyrate acts as a powerful anti-inflammatory agent for the colonic cells, and functions to improve the integrity of our gut by decreasing intestinal permeability and therefore keeping toxins in the gut and out of the bloodstream. (20, 21).
The SCFAs that aren’t utilized by the colonic cells enter the bloodstream, travel to the liver, and spread throughout the body where they exert additional anti-inflammatory effects.
Resistant starch is also associated with decreased risk of colorectal cancer, thought to occur through several different mechanisms including: protection from DNA damage, favorable changes in gene expression, and increased apoptosis (programmed cell death) of cancerous or pre-cancerous cells (22, 23).
Adding Resistant Starch to Your Diet
Some common food sources of RS include green (unripe) bananas, plantains, properly prepared cooked and cooled parboiled rice or legumes, and cooked and cooled potatoes. See this link for a more complete list of RS quantities in food.
However, if you are on a low carbohydrate diet or don’t tolerate those foods well, you can add RS to your diet without adding digestible carbohydrates.
Bob’s Red Mill Unmodified Potato Starch (NOT potato flour) is one of the best sources of RS with approximately eight grams of RS in one tablespoon. Potato starch is generally well tolerated even by those who react adversely to nightshades.
Plantain flour and green banana flour are also excellent sources of RS, and there may be benefit to including all three of these sources (specifically alternating your source of RS rather than relying on a single one).
These are relatively bland in flavor and can be added to cold or room temperature water, almond milk, or mixed into smoothies. But to maintain the benefits of RS, these should not be heated above 130 degrees.
Tim Steele (Tatertot) has written about some of the research on RS supplementation, and in particular the potential further benefit of combining potato starch with psyllium husk fiber to even further increase butyrate production in the colon.
Take It Slow
Studies indicate that the benefits of resistant starch may be seen when consuming around 15 to 30 grams daily (equivalent to two to four tablespoons of potato starch). This may be too much for some people to tolerate, particularly in the setting of gut dysbiosis, and going above this amount is not necessarily beneficial.
If you experience marked GI distress with even small amounts of RS, this may be an indication of SIBO (small intestinal bacterial overgrowth) or microbial dysbiosis, and you may need to consider working with a healthcare practitioner to establish a more balanced gut microbiome through the use of herbal antimicrobials and probiotics before adding RS or other prebiotics.
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So, if these resistant starches do not get absorbed, why can’t low carb eaters eat them? The glucose is not affected, so isn’t this now something everyone may eat?
Did you read the article? Short chain fatty acid production? Ring a bell?
Thank you for sharing this information I really hope that it helps me I’ve been suffering so much from intestinal problems. I really hope this helps will be spreading the good word.
What is the reason for not recommending hi maize resistant starch? I use hi maize hi fiber flour in my baking for my son. If this product is not good, I would like to know. Thank you.
Because Micheal Pollen has written about it in his book ‘ Omnivoires Delema’ and has inaccurately described it. The question asked prior to yours suugests it is not absorbed. This is not accurate. It is absorbed, just not all at once but rather slowly and completely as it passes the digestive tract nourishing all tissues while nourishing the bacteria which benifit you and their numberd actually exceed the number of your own cells. The problem with maize resistant starch is that it comes from corn, a four letter word that has made many journalists and ‘so called experts in nutrition’ wealthy. The other problem is the misconception that high maize is a GMO. It is available in a non-GMO form using natural biodiversity. It is no more a GMO than an heirloom sweetcorn variety used by our ancestors and those displaced by them. There are many ways to get RS starch. I love potatoes, I beleive this a good approach. It is entirely your choice. Hi-maize or other sources of it is one of many sources that has much clinical evidence of its efficacy. A starving, non multi-national agricultural corporate scientist. Be informed, not indoctrinated.
Is it safe to start consuming RS at 10 weeks pregnant? Last year I was diagnosed with higher levels of bad bacteria and yeast overgrowth. I took Nystatin twice to kill it off. During that time, I also removed all yeast and sugar from my diet for 3-4 months. I’ve since allowed myself to have sugar moderately but for the most part I have removed the yeast and gluten. I currently take Klaire Labs Probiotics and I was taking Prescripst Assist Pre-biotics and probiotics not too long ago. I suffer from constipation, mucus in my stool, and sometimes food particles in my stool as well. I think I may have Leaky Gut or SIBO but I’ve never been tested for either. Should I give RS a try even though I’m 10 weeks pregos?
If it feels right, eat it!
This may be especially true of pregnant women and RS. Expecting mothers have an inborn sense to seek out what they need when pregnant.
The term “Pica” describes pregnant women who seek out and eat non-nutritive things, often treated as a mental disturbance! These things? Dirt, chalk, starch, plaster, among others.
Could these ladies have been seeking RS and not know where to find it, so using similar substances?
So, RS is not harmful to consume during pregnancy unless you have been specifically told to avoid “fiber.”
So…what’ll it be? Potato Starch? Banana Flour? Hi-Maize?
Is it okay to take a digestive enzyme while on the RS plan without upsetting the protocol (like Beano) ?
Hi, Tim. Do PS and banana/plantain flour have the same amount of resistant starch? The PS makes my joints hurt a bit so I was thinking about trying banana/plantain starch. Any specific brand recommendations for those?
Any info on yams (not the American sweet potato but west african yams)? I find a lot of shops that sell it near me, even organic yams, and I am curious if anyone has any info. Cassava as well. One other product, Lupin starch. I have seen it in my shop but don’t know that much about it.
African yams are starchy, so they can also be a source of RS (in widely varying amounts). My favorite tasting yam so far is yellow yam (Dioscorea cayenensis) from Jamaica and Mexico (they are not organic, though). The father of Usain Bolt, the world’s fastest man, claims that yellow yam is the secret to Usain’s success. 🙂 http://voices.washingtonpost.com/dcsportsbog/2008/08/on_usain_bolts_magical_yams.html
Make sure you learn how to handle and cook yellow yam before doing so. There are good Youtube videos on it.
Hello!
Thank you very much for your website.
I am writing from Europe.
I would be grateful if someone could tell me if potato starch could cause problems in absorb minerals, vitamins or nutrients.
A joyful day for all of us!
I’ve read that good coconut oil is good for absorption problems.
Coincidentally, both coconut oil and RS provide short chain fatty acids–coconut oil delivers them mostly in the stomach and RS mostly in the colon.
SCFAs “stimulate colonic blood flow and fluid and electrolyte uptake” (http://www.ncbi.nlm.nih.gov/pubmed/11427691), which may help explain how it improves status of certain nutrients, like Mg.
I am on Modified Atkins Diet for epilepsy and often add MCT oil and use coconut oil to add fat to my diet. Short Chain Fatty acids are often a way to add fat to the diet. Also, I read that being on low carb diet, I should be sure to have RS in my diet. Sounds like adding small amounts may be a win win for Keto type diets.
I know you wrote this some time ago but I just found it. I am also epileptic and am interested in following a ketogenic lifestyle. Can you give me any tips, advice etc, and were you able to go off your meds? Many thanks.
Resistant starch actually appears to have improved my absorption of minerals and vitamins and I need far less supplementation (such as Mg and B6) than I did when I was eating a LC Paleo diet that was very low in RS and starch in general. Research also links RS to improved vitamin/mineral production and absorption:
RS improved Mg absorption in rats: http://jn.nutrition.org/content/133/1/1.full
RS and other prebiotics feed lactobacilli: http://onlinelibrary.wiley.com/doi/10.1002/star.201000099/pdf
Lactobacilli that feed on RS produce B vitamins: http://www.ncbi.nlm.nih.gov/pubmed/21933312
Wow, thank you for this information PaleoPhil. I just received my first order of RS and this info really helps me understand how it works and why.
Is it okay to still use digestive enzymes with a resistant starch diet?
Great question. I’m interested in the answer too.
Yes. I’m taking enzymes and HCI, so I also would be interested in an answer to this question.
Is it okay to take digestive enzymes while following a resistant starch diet?
I would love for anyone to answer this question:
Monday I ate a dish containing 1/3 cup of white rice.
Post meal checks showed that my blood sugar topped off at 151. Today I ate the same dish with the same amount of COOLED white rice. In addition, I ate two small RAW potatoes beforehand in an attempt to increase the resistant starch. However, after eating the rice dish, my blood sugar topped off at exactly 151 again. It appears the resistant starch had no glycemic lowering effect. Thoughts?
Peggy – You are seeing that RS is not a “pill” for lowering blood-glucose. Your experiment has been replicated many times in the lab, with the same results…no effect.
However, when you allow the RS to do what it is good at, ie. making beneficial changes to your gut flora, and in turn, a host of metabolic improvements, then you may start to see the BG lowering effects.
Also, BG improvements are generally seen as improvements to the “are under the curve” (AUC). To see this for yourself, you’d need to test your post-prandial blood glucose at about 10 minute intervals after eating, plot out a chart, and then do the exact same chart later to compare to a baseline. This is actually a very enlightening experiment, and if you have unlimited strips, I would suggest you do it.
For instance, the first meal you describe above, possibly your pp BG spiked to 200 at the 30 minute mark, but was at 150 when you tested it. In the second meal, maybe it only spiked to 170 at its highest, but you managed to capture it at 150 again.
A single BG poke is simply a snapshot of your GB at that instance and does not give a picture of the journey it took getting there.
Hope that helps!
Bottom-line: RS increases insulin sensitivity, but may take time. To see if it is working, a baseline curve must be developed to compare against.
Sorry, fast fingers: AREA Under the Curve (AUC), and the GB towards the end was supposed to be BG.
Tim, I really appreciate your response. I did check my BG every 15 minutes for about 3 hours after eating the rice. (BTW, I found it took about 3 hours for my BG to return to baseline.) It sounds like I need to try the potato starch and stick with it long enough to give it a chance to improve my gut flora and see what other positive effects it might have. I will do the graph as you suggested. Thanks!
Ok this is response to the comment above by Peggy. I have had diabetes for 42 years. Diagnosed at age ten. I now have an insulin pump so I have a little drip of insulin 24 hours a day and when I eat a meal I take extra insulin to cover the carbs in that meal. I have been eating green banana smoothies since September 1st, 2015. I usually use 1/3 cup frozen very green bananas in the blender with a tablespoon organic coconut milk from the can, 3 tablespoons organic frozen blueberries and a few squirts of organic liquid stevia. I add about 1/4 cup water and blend into a smoothie. The resistant starch from the green bananas has worked incredibly well in keeping my blood sugars more stable. I usually eat this smoothie an hour before bed on either a full or empty stomach. When I get up I feel fantastic. It has helped keep inflammation in my body down, especially my feet and hands. It also greatly helps with my digestion and I never feel bloated or full. It takes away a good portion of brain fog and it definitely reduces my cravings to eat even when I’m not hungry, especially in the evening! I figured out I have leaky gut syndrome 3 months ago and the green banana smithy has helped tremendously in making me feel better both mentally and physically. Going to have all the stool, urine and blood testing done at Great Plains Laborstories online, to confirm my self diagnosis. But to any of you that are suffering from elevated blood sugars wether you are diabetic , borderline diabetic, gestational diabetic, the green bananas will help you with blood sugar control AND loosing weight. Since I started on September 1, 2015 and as of today , I have lost 10 pounds, because of not having such extreme cravings to eat at night( especially cravings for sweet tasting things. It really is an incredible discovery and I hope that one day it becomes well know so it will help all diabetics have better control. Incidentally, I recently read that diabetes is contracted due to ingesting a fungus. It will be interesting to see if after taking anti-fungals for this leaky gut syndrome, will improve my blood sugar even further, to the point that I need very tiny amounts of insulin when I do eat a big serving of fruit or other carbs. I also noticed that I feel calmer and sleep much better since using the green bananas. Incidentally, I first used the potato starch from bobs redmill brand and a few other brands, but it did not work for me at all. Sorry this is so long…. By the way, I only need to lose about 6-7 more pounds to be perfect body weight, and u eat a super healthy diet for two years consisting of only: grass fed beef, grass fed butter, grass fed eggs and mostly low carb organic broccoli, spaghetti squash and cabbage with a few other veggies and salad. Olive oil and water with lemon and stevia to sweeten it. Even on this diet I could not loose weight until I started eating the green bananas. Ok so I hope this helps some of you struggling with inflammation, brain fog, food cravings, sleep problems and general all over pain. I am the diabetic Guinea Pig!?
I only use Organic green bananas…
How are you using them? Raw in smoothies?
Wonderful info, Linda, thank you. And, great job experimenting and sharing what works — and what didn’t. 😉
Peggy stated that she ate RAW potatoes. I was under the impression they must be cooked and cooled to be beneficial?
I think it takes a while. Maybe 10 days
Hello Chris.
I think i have some Form of leaky gut so therefor i drink kefir everyday.
I usually do a second fermentation with prebiotics like Onions or plátano starch to give the probiotics a head start on consuming them before they arrive the small intestines in csse i have SIBO.
Does this make sense?
is freshly juiced raw potato juice good source of RS?
Grainbrain by Dr. Purlmutter says that corn, potatoe and soybeans are no nos. You say that rs upon cooking at high temp will convert them to a digestible form. But if one uses the high temp and then cool to 130 degrees or less will render them undigestible and they will go to the gut to for prebiotics.
I just want to make sure that I read all of this correctly.
Also, I froze greek yogurt and wonder if the probiotics would be dead and if so is there a way of adding probiotics back to it?
Something that increases metabolism, decreases inflammation and improves stress resistance should be on everyones menu.
GREEN BANANAS! ?
I should say that I only use ORGANIC green bananas!
taking digestive enzymes while attempting resistant starches, any problem with this combo?
Thanks.
I’m not looking for weight loss or improvement in my gut! My gut has never given me any problems, for which I am thankful. However, I have been on the Paleo Approach diet for about 6 months now. I had several borderline and slightly elevated blood tests which are now in the normal range. But I am losing more weight that I thought I would, so am beginning to add a few things back into the diet. I’d appreciate any comments or other suggestions. Blessings and thanks, Estelle
Hi,
I really need some Inf. about how producers produce RS in industrial scale??
If there is special instrument or methods, what are they??
I’d be thank full if you help me by this issue.
Thanks.
Hello,
I have just bought a packet of unmodified potato starch, i wanted to know if it is ok to soak it overnight in milk before taking it, or if the milk and or the soak would be detrimental to the resistant starch?
Soaking it won’t do anything at all good or bad to the starch. It is not soluble in water (or milk).
Thank you so much Dr Amy for this very clear article!
I am have been curious to know why there is a recommendation across the board in our community regarding using Bob’s Mill Potato starch. I understand that it is not organic and they do not have any specially high standard for sourcing the potatoes. I have seen evidence that potatoes may be one of the most contaminated foods in the dirty dozen list. I put my two cents here, for us to start recommending organic potato starch. Thanks again for the great article! It has been very helpful! Cheers!
Bob’s Red Mill potato starch happens to be what the guy who inspired the potato starch experiments tried. It was the one he happened to find at the supermarket and it’s also relatively cheap. If you’re concerned, there is at least one organic brand and there are other alternatives. You can even make your own.
Thanks Paleophil. Very kind of you to reply. Actually, I am covered. I have always used the organic one only and find it awesome!
The purpose of my post was to invite whoever is interested, to question the use of the conventional starch, which seems to have become the “norm” across the web. Cheers.
Not all organic potato starches say unmodified.
From what I have read, that is critical.
How timely, I just put together a page with links to RS products I have thoroughly checked out and use. My RS2 Picks
The term “unmodified” is not as important as seeing the term “modified”. When buying look specifically for the terms “modified” or “pre-gelled” these are definitely not the right product!
Until someone develops a resistant starch supplement that has been tested for RS, it’s a bit of a crap-shoot. Hi-Maize cornstarch is about 54% RS2 and has been used in 1000’s of studies. You can find a link at the above page, but in 50 pound bags.
Thanks for the links to RS products. I have been interested in finding organic RS also.
Tim, I am just getting into the RS concept. I know that your list of RS2 sources was added to this site many months ago. I’ve contacted Bob’s Red Mill and they don’t make any claims about the RS content. Does someone have better information? I bought a bag from them but feel it could be a waste of time.
Just a note that Hi-Maize is a Resistant Starch 2 and not a chemically modified starch which is Resistant Starch 4. Hi-Maize has numerous health benefits ranging from Digestive Health to Blood sugar management.
Remember that most corn is GMO.
I finally got around to looking at Hi-Maize. It is non-GMO certified, but not organic. It can be cooked with, to a point, the RS surviving most gluten-free baking methods, or used in a smoothie.
I made some pancakes yesterday with about 50% Hi-Maize…turned out great.
This is the stuff. Hi-Maize 260, 50 pound bags, $140
The info says it also comes in 5 pound bags, not sure how to get those.
Hi, I’m hypothyroid and have discovered that any form of maize (corn) is bad for thyroid health; so are most soy products.
where did you find info on it surviving baking? thanks.
Thanks for a great article.
In it, there are several references to “properly cooked” and parboiled rice.
1- Can you please elaborate on “properly cooked”?
2- Can you please explain the difference between parboiled rice and brown rice in this context?
Thanks!