Resistant Starch, What You Need To Know
The first time I heard about STARCH was when I saw it on TV — back in the 60’s — it was being sprayed onto the collars of shirts when ironing.
Obviously… NOT the same starch that I am telling you about today… which is Food Starch.
Food starch is basically a long chain of glucose that is found ONLY in plants, some examples are seeds, grains and root vegetables.
Some are digestible meaning that digestive enzymes help break them apart for digestion in the mouth, stomach and small intestines.
Others are what we call ‘Resistant’ Starch – indigestible – and travel through your stomach and small intestines – undigested. Finally, they reach your large intestines where they are either slowly or rapidly fermented by beneficial gut microbes which in turn create Short Chain Fatty Acids (SCFA) primarily acetate, propionate, and butyrate and some gases (i.e. result is flatulence).
Now the ‘flatulence’ can be a bit of a worry at times, especially if silent and deadly, or odourless but noisy, but the good news is that eating these types of ‘starches’ is definitely worth it… as the end product are Short Chain Fatty Acids [SCFAs] (read more here) the KEY to optimal health and proper function of intestinal cells. In fact, a low production of SCFAs have been linked to poor health and disease.
“the low fibre and high fat content characteristic of the western diet fundamentally changes the gut microbiome,
resulting in deficient production of immunomodulatory metabolites, particularly SCFAs”
In fact, the average person only gets about a quarter of the resistant starch needed for health.
Now remember there are over a 100 trillion cells in the body and 90% of these are gut microbes and to keep your beneficial gut microbes healthy and functioning you need to feed them!
THE 4-TYPES OF RESISTANT STARCH
Now you’d think there would be just one kind of Starch, to make it easy, hey? But there are 4-types.
Some foods contain more than one-type of resistant starch.
Then… there are changes to type of Starch depending on whether it has been cooked or cooled and then others depend on how ripe it is E.g. A green un-ripened banana is full of Resistant Starch [RS], but when it turns yellow and ripens it turns into a regular starch.
RS1: Found in seeds, grains, beans and legumes. It resists digestion because it’s firmly bound within the cell wall of the plant making it physically inaccessible.
RS2: Found in unripe (green) bananas and raw potatoes. Due to the tight packing of starch within the granules it is resistant to enzymes.
RS3: Is referred to as a ‘retrograded starch’ which forms when cooked starchy foods are cooled e.g. cooking rice and potatoes and letting it cool reduces its digestibility. You can reheat these starches and they STILL remain resistant starch!
RS4: Results from chemical treatment/modification of starch e.g. chemically modified potato starch. Studies show that certain chemically modified starches may be resistant to after consumption.
More recently there has been talk of type 5 (RS5) Where the amylose (one of the two components of starch) forms complexes with lipids (fats) in the food. These too are modifications of starch and are NOT what I consider to be ‘real’ food.
RESISTANT STARCH HEALTH BENEFITS
The benefits of ‘starches’ are many, but to name a few… they work as a powerful anti-inflammatories, modulate your appetite, increase feelings of fullness, improve blood sugar levels, keep your immune system functioning, keep your skin in tip top shape, improve insulin sensitivity, improve mood and reduces your risk for chronic disease.
But what if I told you that ALL of this is due to your GUT MICROBIOME! Because your beneficial gut microbes ferment these Resistant Starches and produce Short Chain Fatty Acids (SCFA) – primarily Acetate, Propionate, and Butyrate…. which in turn provide these amazing HEALTH BENEFITS…
Keeps skin glowing and healthy… “Propionate, acetate, and butyrate – are believed to play a pivotal role in determining the predominance of certain skin microbiomic profiles” … they play a key role in the skin immune defence system.
Keeps your Colon in tip top condition… You may be wondering why you need to keep your Colon in good condition. Does 100 deaths a week from Bowel cancer make you want to sit up and take notice? Bowel cancer is the second most common cancer (males/females) in Australia, more commonly found in those over the age of 50. Resistant starch and fibre and most importantly the by-product of its fermentation is… “Butyrate (which) provides energy for colonocytes, reduces oxidative stress” and furthermore… “Butyrate regulates colonic motility, increases colonic blood flow and may enhance colonic anastomosis healing”
Lower risk of colon cancer… “Epidemiologic studies have shown a significant positive association between fat and meat and the risk of colon cancer and a reduction in risk in individuals and populations consuming high amounts of dietary fibre and vegetables”
Potent anti-inflammatory… “Butyrate is primarily derived from dietary fibre by anaerobic bacterial fermentation in the colon and exhibits potent anti-inflammatory activity”
Cancer prevention… “Recent evidence suggests that resistant starch (RS) is the single most important substrate for bacterial carbohydrate fermentation in the human colon”… suggesting that “RS has potentially important effects on bacterial metabolism in the human colon that may be relevant for cancer prevention”
Improves insulin sensitivity… “We examined the role of butyric acid… butyrate can prevent and treat diet-induced insulin resistance in mouse” Insulin resistance is a risk factor in the prevalence of diseases such as Cardiovascular disease, Metabolic syndrome, High cholesterol and triglycerides, increased abdominal obesity and Type 2 diabetes.
Aid digestive disorders… “Short chain fatty acids may modulate tissue levels and effects of growth factors in the gut and so modify gut development and risk of serious disease” and has had impressive results in the treatment of IBD, possibly due to … “Butyrate may reduce the symptoms from ulcerative colitis and diversion colitis and it may prevent the progression of colitis in general”
Improve Iron and Calcium absorption… “A meal containing 16.4% resistant starch resulted in a greater apparent absorption of calcium and iron compared with a completely digestible starch meal… administration of resistant starches could have a positive effect on intestinal calcium and iron absorption”
Improve Mineral absorption… “Resistant starch and inulin are complex carbohydrates that are fermented by the microflora and known to increase colonic absorption of minerals in animals. The fermentation of these substrates in the large bowel to short-chain fatty acids is the main reason for this increase in mineral absorption”
Reduces anxiety and depression… “Resistant starch stimulates bifidobacterial growth, which has been shown to significantly reduce waking cortisol response, a stress hormone strongly linked to anxiety and depression”
I could keep writing, and citing research, about all the amazing benefits of Resistant starch but I think you get the picture. Now you’re probably screaming at the computer right now… Saying… “Nat!!!! Just give me the list of foods with resistant starch” Okay, okay, but before I do… Understand a couple of things…
You need a VARIETY of foods in your diet – not just the list of foods below.
Health is not just about what you put IN your body, it’s about taking out health-eroding foods.
Gut Microbiome health is NOT just about the food. Lifestyle elements are KEY to a health Microbiome. E.g. How you eat, Stress, Movement, Sleep, etc.
That adding these foods, suddenly, can cause digestive complaints.
FOODS HIGH IN RESISTANT STARCH
Oats… Good old porridge! Cooked and eaten warm provides resistant starch. Cooked and cooled helps to increase the resistant starch component.
Beans and Legumes… Some examples are…. Peas, Lentils, Lupins, Chickpeas, Beans such as Kidney beans, Black beans, Black-eyed beans, Cannellini beans, Pinto beans, butter beans, adzuki beans and soybeans to name a few… the list goes on. Of course, these should always be soaked and cooked before eating. And if they are cooled, and part of a salad, even better!
Unripe Bananas… are high in resistant starch. Once they turn yellow they become simple sugars. So, buy a bunch of unripe bananas peel and freeze them to add to smoothies or make ice-cream. And when just munching on a banana, choose a green/yellowish and save the super ripe bananas for making banana bread!
Rice… Is a good source of resistant starch but when cooked, then cooled for 24-hrs the amount of resistant starch increases quite substantially. So, to save time, and get more resistant starch, cook a big batch of rice (either white or brown Basmati) at the beginning of the week, let cool and then freeze in portions. Then when you want to add to your meal, take it out, defrost and reheat. The great thing about doing it this way is that it saves you time too!!
Whole Grains… Such as buckwheat, quinoa, wheat, maize, spelt, freekeh barley, millet, amaranth (tiny amount) to name a few. They are a wonderful source of fibre, vitamins and minerals and resistant starch. With most grains the cooking, then cooling, slows down the rise in blood glucose levels. Here’s an example for wholegrain organic pasta…
Cooked - eaten straight away… blood glucose levels rise to 2.2-2.5 mmol/l.
Cooked - chilled overnight… blood glucose levels rise to 2.0 mmol/l.
Cooked - cooled for 24 hours and reheated… blood glucose levels rise to 0.1 mmol/l. A 41 % reduction in glucose between freshly cooked and chilled/reheated pasta.
Potatoes…When cooked, then cooled for 24-hrs the amount of resistant starch increases quite substantially. Cold potato salad, roast potatoes, potato soup — all great forms of resistant starch. Sweet potatoes have resistant starch too, but not just as much as regular potatoes.
I hope this article helps you and your health.
If you want to know more about my programs that are designed to IMPROVE your Gut Health then head HERE or if you want to eat your way back to health — one meal at a time — check out my Gut Health Recipe Compendium. Nat xx
REFERENCES
(2018) The Gut Microbiome as a Major Regulator of the Gut-Skin Axis.
(2017) Impact of Dietary Resistant Starch on the Human Gut Microbiome, Metaproteome, and Metabolome.
(2017) Resistant Starch Regulates Gut Microbiota: Structure, Biochemistry and Cell Signalling.
(2016) The potential of resistant starch as a prebiotic.
(2013) Resistant Starch: Promise for Improving Human Health.
(1997) Butyrate and the colonocyte. Production, absorption, metabolism, and therapeutic implications.
(1992) Fecal weight, colon cancer risk, and dietary intake of nonstarch polysaccharides.
(2014) Advances in Nutrition and Cancer. Diet and large bowel cancer.
(2007) Review article: the role of butyrate on colonic function.
(2012) Butyrate suppresses colonic inflammation through HDAC1-dependent Fas upregulation and Fas-mediated apoptosis of T cells.
(1998) Effects of resistant starch on the colon in healthy volunteers: possible implications for cancer prevention.
(2009) Butyrate improves insulin sensitivity and increases energy expenditure in mice.
(2000) Starches, resistant starches, the gut microflora and human health.
(1996) Effect of resistant and digestible starch on intestinal absorption of calcium, iron, and zinc in infant pigs.
(2001) Effects of two fermentable carbohydrates (inulin and resistant starch) and their combination on calcium and magnesium balance in rats.
IMAGE: (2017) Resistant Starch Regulates Gut Microbiota: Structure, Biochemistry and Cell Signalling.