Resistant starch (RS) is a type of carbohydrate that our digestive enzymes cannot break down in the stomach or small intestine. They therefore reach the colon intact, “resisting” digestion.
This explains why we do not see spikes in either blood glucose or insulin after eating food rich in RS and why we do not obtain significant calories from RS.
I feel like RS is an overlooked area of repairing our gut. In my practice, more and more clients incorporate RS into their diets and get wonderful results – especially those struggling with digestive issues and chronic case of candida overgrowth.
The key benefit is simple: RS is food for probiotics (whether you take them in the form of a pill or in food – I’m a proponent of doing both). In other words, it’s a prebiotic we often hear about. I’ve found the often cited prebiotics in the form of inulin, artichoke etc to be problematic for many people especially those with IBS (irritable bowel syndrome) and leaky gut. It’s no surprise because many prebiotics are high on FODMAPs whereby food rich in RS is not.
The role of the gut in hormonal balance (including the thyroid)
Many people wonder why do I go on and on about the health of our digestion when we struggle with hormonal issues. I completely understand – the connection may not be clear right away.
In short: there are three main reasons.
The first being that chronic digestive issues such as constipation, loose stool, bloating, acid reflux, indigestion are perceived as stress and additional cortisol (stress hormone) is produced to help deal with the digestive stress. When this is on top of all the other adversities many of us need to deal with on a daily basis, digestive issues can further worsen adrenal exhaustion.
If you have been following this blog for a while, you know that a healthy gut is key in restoring our thyroid function and containing the autoimmune attack (if you have Hashimoto’s disease).
The second being that 70% of serotonin is produced in the gut and serotonin has an upregulating function of other hormones including estrogen and progesterone (source).
The third and most recently discovered is the role of the estrobolome – a subset of gut bacteria that helps with the metabolism of estrogens, especially the dangerous estrogen metabolites responsible for breast, ovarian and thyroid cancers (source).
This is where RS comes in. Many of us already take probiotics and/or eat a cup of fermented foods daily to heal our digestion or to maintain good health. RS-rich food can further help by colonizing the gut with the good bacteria in a consistent and effective manner.
From my personal experience and the journey of many women I’ve worked with, I see faster healing happen when RS-rich food is added. This applies to healing of the GI lining as well as clearance of candida (which 70% of women I work with suffer from).
Resistant starch and butyrate = less inflammation
One of the key benefits of RS is butyrate production which happens as a result of the fermentation in the gut.
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 (source).
Butyrate is also a powerful anti-inflammatory agent for the colon 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.
If you experience GI distress (such as discomfort, gas and bloating) with even small amounts of RS, this may be an indication of SIBO (small intestinal bacterial overgrowth) or some other form of microbial dysbiosis.
Food high in resistant starch
I’ve done lots of research on this as there is contradictory and incomplete information out there and I’ve found Chris Kresser’s article to be most comprehensive and well researched.
Here is the scoop, from his blog:
“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.”
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.
Benefits of resistant starch
And there are many:
- Feeds “good” bacteria responsible for butyrate production. This applies to the bifido and bacillus bacteria which many people are deficient in. People who were not breastfed have a tendency to be low in bifidobacterium so RS gives a wonderful opportunity to colonize our gut with the good guys.
- May preferentially bind to and expel “bad” bacteria – this explains why people with candida do very well on RS.
- Improves insulin sensitivity – this is especially important for women with sugar fluctuations and PCOS (but not only).
- Improves the integrity and function of the gut.
- Reduces fasting blood sugar. This is one of the most commonly mentioned benefits of RS, and the research seems to back it up.
- Increases satiety.
What about potatoes as nightshades and beans?
Yes, nightshades can be a problem for some people, especially those with rheumatoid arthritis and chronic body pains and aches. I have found that many people who can’t eat potatoes, do not react to the unmodified potato starch. I would therefore encourage you to try it. As always, go slow when introducing any new food, starting with ¼ of a teaspoon before you build it up.
I am reluctant to recommend beans and legumes. When cooked, they contain RS as well but I find that most people are having lots of difficulty digesting them, even when soaked and sprouted.
How to add RS-rich food to your diet?
Here are a few of my recommendations:
- Green plantain flour – since it can’t be heated in order to retain RS, the easiest thing to do is to add it to your morning smoothie. Its “chalky” texture might feel a little strange when dissolved in water but it blends really well into a smoothie.
- Cold potato salad – see my new recipes that goes back to my Eastern European roots and also incorporates sauerkraut. So, a prebiotic and a probiotic in one meal.
- Rice salads – any cold rice salad would be a good addition. Cold sushi will also do the trick.
Unfortunately, I’ve found that plantains cannot be heated and cooled to get the same RS effect as potatoes, rice and beans. Bummer.
As always, start adding RS-rich food slowly and build up.
In health and happiness.