What is resistant starch and why you should consume it
Becca Crawford
Resistant starch is all the rage right now in the ancestral health community. I have been receiving numerous enquiries over the past few months about resistant starch and how to consume it. Firstly I want to point out that I don’t follow trends. I try to understand the science behind something before I alter any of my lifestyle choices. So let’s start with the science and a potted summary of gut health because this is where it all begins….
- Our health depends on the health of our gut (by “gut” I’m referring to the Gastro-Intestinal tract that runs from the mouth to the anus).
- The health of our gut in turn depends on the balance, number, location and strains of bacteria that live there (this bacterial film is often referred to as our microbiota, microbiome, or gut flora).
- The bacteria that live in our gut span the spectrum of good or friendly bacteria (called probiotics or ‘old friends’) on the one hand and bad bacteria (pathogens) at the other end of the spectrum with a heap in between.
- The good guys should outnumber the bad guys by 85% to 15%. The location of that bacteria is really important: they should mostly be in the colon, the large intestine.
- When the balance or location or the different strains of bacteria is out of whack, our health is compromised, either in some minor way (eg reduced immunity leading to colds and infections. NB 75% to 80% of the immune cells in the body are in the gut, so changes to your gut microbiome are absolutely going to affect your immunity and your ability to fight off infections) or acutely (eg SIBO, leaky gut, brain and/or skin disorders, autoimmunity).
- There are a number of factors that affect our intestinal bacteria, diet being one of them (others include antibiotics, the sterility of our environment, C-section versus vaginal birth, the contraceptive pill, acid-stopping drugs, smoking, the use of colonics, environmental toxins, pesticides, heavy metals).
- Anthropological evidence shows that many strains of good bacteria that appeared in our hunter-gatherer ancestors have permanently disappeared from the modern gut today. We pass on our microbiome down to our children through birth from generation to generation so the state of our health and our lifestyle choices today will affect the health of future generations. As Chris Kresser recently put it “if we change or eliminate certain species of gut flora that have been living in our guts for millions of years or hundreds of thousands of generations and we wipe them out, we’ve permanently changed essentially what it means to be human because we have 10 times more bacterial cells than we do human cells, so it’s a big deal.”
- I wont go into all the details on what the good bacteria do for our health but without them we can’t survive and we need them for strong immunity, healthy digestion, good brain function, healthy skin, calm nervous system, and a well-functioning metabolism.
A diet rich in lacto-fermented foods provides natural probiotics (good bacteria) that populate our gut. But once the good bacteria are there these essential little critters need to be kept alive and kicking. Enter prebiotics. Prebiotics are the food for the probiotics already in our gut to keep them alive and healthy. So we need a diet rich in both probiotics (to populate our gut with new strains of good bacteria) and prebiotics (as their fuel source). Fortunately a nutrient-dense traditional wholefoods diet can provide, for most people, a good source of both without resorting to over the counter supplements. I always try to obtain my nutrients from wholefood sources wherever possible. Prebiotics are generally classified into three different types: non-starch polysaccharides, soluble fiber, and resistant starch (RS). Each of these types of prebiotics feeds different species of gut bacteria, but of these, RS is most recently donning the spotlight for its ability to lower blood glucose levels, improve insulin sensitivity (which contributes to fat loss), act as a powerful anti-inflammatory agent and maintain the integrity of our gut by decreasing intestinal permeability. RS is a type of starch that is not digested in the stomach or small intestine, reaching the colon (the large intestine) intact. Thereby “resisting” digestion. This explains why RS does not result in spikes in either blood glucose or insulin, and why we do not obtain significant calories from RS. Once RS reaches the large intestine, bacteria attach to and digest, or ferment, the starch. This is when we receive the benefits of RS.
Examples of RS include:
(a) starch found in grains, seeds, and legumes;
(b) starch found in raw potatoes, green (unripe) bananas, and raw plantains. Cooking these foods causes changes in the starch making it digestible to us, and thus removing the RS;
(c) retrograde RS since this type of RS forms after RS found in foods listed in (a) or (b) above are cooked and then cooled for 24 hours. Examples include cooked and cooled parboiled rice, cooked and cooled potatoes, and cooked and cooled properly prepared (soaked or sprouted) legumes.
Since many of my clients and people who follow a nutrient-dense traditional wholefoods diet do not eat much if any grains, seeds and legumes, and since raw potatoes and green unripe bananas are not so tasty and since plantains are rare as hens teeth in Australia well that just leavescooked and cooled potatoes as our most practical wholefood source of RS. To that end I have put together the following 2 simple recipes incorporating cooked and cooled potatoes that I am now incorporating into my and my kids’ diet:
In the coming weeks I will also post recipes for avocado and raw salmon nori rolls and Greek rice pudding (both incorporating cooked and cooled white rice- properly soaked then rinsed before being cooked then cooled).
Kids typically love all of the above dishes so adding them into your culinary repertoire shouldn’t be a hardship. They are a convenient lunch box idea (obviously make them the day before) as well as fun summer time food perfect for picnics and easy dinners when you don’t feel like eating hot food. At it’s most simplest level you could get into the habit of adding some chopped potatoes to your evening steamed veggies then pop all or some of them in the fridge to be consumed the following day in kids’ school lunch boxes and into your salad for lunch. Just a thought.
How often do I eat cooked and cooled potatoes? At least once if not twice a week. A little less often in the case of cooked and cooled white rice. So I guess this has been a change for me, in a practical sense, since reading about RS. I’m not sure how important the 24 hours of cooling is prior to consuming the cooked and cooled potatoes. In my household sometimes these dishes get consumed in less than 24 hours of being cooked but if you can be a little organised and prepare ahead of time then all the more power (and prebiotics) to you!
To read a more comprehensive article on prebiotics and RS written by Chris Kresser click here (I have essentially condensed and summarised the punch lines for you in this blog post). In his article Chris points out that if you are on a low carbohydrate diet or don’t tolerate potatoes well you can add RS to your diet via unmodified Potato Starch (NOT potato flour), plantain flour and/or green banana flour (by adding to cold or room temperature water, almond milk, or mixed into smoothies). His article comes with the usual caveat that if you suffer gastro-intestinal tract 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. To that end for those of you living in Sydney I highly recommend working with a holistic practitioner on the same nutritional page such as integrative GP Dr Min Yeo or natropath/herbalist Anthia Koullouros (both at Ovvio Paddington 5 Ways). If you live in Melbourne I have a list of like-minded practitioners that I can email you