Resistant Starch Guide
Many of the world’s longest living populations eat a diet heavy in something called resistant starch (up to 70%). Resistant starch is a class of prebiotic fiber that travels all the way to the colon, where our gut bugs ferment it into fatty acids that boost our mitochondria (and longevity), among other benefits.
Resistant starch in foods, however, is complicated subject matter. Not all experts agree on what and how certain foods should be consumed to maximize our intake. The richest documented sources are raw potato starch, green bananas, plantains, cooked-and-cooled potatoes, cooked and cooled rice, parboiled rice, and cooked-and-cooled legumes. You can see how these sources would be problematic for a beginning Plant Paradoxer. (4)
Plant Paradox Resistant Starches
The following is a list of foods under the Resistant Starch category of the Plant Paradox Yes list:
If you’re just starting out on the Plant Paradox, I recommend simply eating from the list without worrying about the amount of resistant starch you’re consuming. There will be plenty of time down the road to experiment with different preparation methods when you’ve got a good handle on the diet.
However, be conscious that most whole foods contain a combination of starches: slow-digesting, quick-digesting, and resistant. And often this starch profile changes when you cook the food. In fact, most raw resistant starch is destroyed when you cook it. So unless you are preparing these foods a certain way, you may mostly be consuming digestible starch.
Three Types of Resistant Starch
There are more than three types of resistant starch, but for the purposes of this diet, we need only concern ourselves with these three:
- RS1 – the highly indigestible starch present in coarsely ground or whole kernel grain and seed products (i.e. sorghum, millet, teff, legumes) – sometimes destroyed by cooking
- RS2 – starches with an indigestible crystalline structure, present in raw foods like potatoes, unripe bananas/plantains, and tiger nuts – destroyed with cooking
- RS3 – also called retrograde starch, long-branched starch that forms only after cooking and cooling certain foods (i.e. white potatoes, white rice, and legumes)
Beware Raw Starch (RS2)
Dr. Gundry has, several times, mentioned that type RS2–found in raw foods like potatoes, tiger nuts, and green bananas–feeds bad gut bugs. This may be because RS2 alone has been shown to reduce the protective bacteria in our guts associated with longevity. Studies show that RS2, without the presence of other indigestible fibers, “burns quickly” in the colon and does not ferment slowly enough to produce the optimal benefits that RS3 does. (3) (6) (7)
Unfortunately, raw green bananas and green banana flour are some of the highest RS2-containing foods on the list (see below). However, when they are cooked at a temperature higher than 180 degrees F, the RS2 becomes digestible, and the banana (or green banana flour) loses nearly all of its resistant starch. So, while unripe fruits like bananas are on the Yes list as resistant starches, they are not the best source, raw or cooked. (4)
Say Yes to Cooked Starch (RS3)
So if we’re minimizing raw RS2 starches because they feed our bad gut bugs, how do we maximize the kind that’s good for us? Dr. Gundry mentions in this podcast that the kind our good gut bugs like is slow-fermenting RS3, which forms not when you cook a resistant starch, but when you cool it after cooking.
The problem is, not all foods on the Yes list form a significant amount of resistant starch after cooking and cooling. Sweet potatoes, for example, hardly form any, while certain legumes and lentils are a great source. In fact, cooked-and-cooled white rice, white potatoes, and legumes are some of the richest sources of this type 3 resistant starch. But since potatoes are out and white Basmati rice should wait to be reintroduced, our safest bet for feeding our gut bugs the kind of resistant starch they want could be pressure-cooked-and-cooled legumes! (3) (5) (8)
Resistant Starch Recipes
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Best Cooking & Cooling Methods
Certain methods of cooking yield higher amounts of type 3 resistant starch than others. Because there is a lot of data available for white potatoes, we can use what we know about these and apply it to the other foods found on the Yes list:
Resistant Starch Content for Various Cooking Methods– Potatoes (per 100 g)
- Roasted and cooled: 19.2 g
- Boiled and frozen for 30 days: 5.71 – 12.2 g
- Steamed and cooled: 5.8 g
- Boiled (not cooled): .16 – 4.62 g
- Chips: 3.5 – 4.5 g
- Fried (not cooled): 2.8 g
- Baked (not cooled): .17 – 1 g
Based on this data, it appears our best bet is to roast or boil our resistant starch veggies and then cool them or even freeze them for an extended period of time. It’s also important to note that RS3 is heat stable at temperatures below 130 degrees F. This means, after cooling, you can gently reheat these vegetables and they will not lose that RS3 value. (1) (2)
Although some general sources disagree, studies show that the resistant starch found in grains like sorghum is unaffected by cooking. That means we can use sorghum and millet flours in baked goods without losing the resistant starch value. (Be aware–although these grains contain some resistant starch, a lot of the starch is also digestible, making for a high carb load). (5)
Varying Resistant Starch Content
Even for foods that have been studied frequently, it is nearly impossible to get an exact number of the resistant starch amount, due to all the factors that can effect it. All of the following can affect the amount of resistant starch a food has:
- size and type of starch granules
- physical form of grains and seeds (whole vs. ground for flour)
- genetic engineering
- location of crop
- presence of other nutritional components (i.e. fat, other prebiotic fibers)
- food processing method
- individual chewing habits
That’s right–everything from where your food was grown to how you chew and swallow it can affect the amount of resistant starch it has. For this reason, most data on resistant starch in foods is represented as a range, rather than a set number. (2)
Resistant Starch Content in Foods (per 100 g)
Here is a list of the resistant starch ranges for some of the foods found on the Plant Paradox Yes list. Ranges listed are for cooked or pressure-cooked foods, unless otherwise specified. (1)
- Raw unripe banana: 4.7 – 34 g
- Raw green banana/plantain flour: 35 – 68 g
- Cooked green banana/plantain: .8 – 3.5 g
- Raw ripe banana (for comparison only): .3 – 6.2 g
- Yams: 4.3 – 23.25 g
- Lentils: 3.4 – 13.8 g
- Black beans: 10.76 g
- Cassava root: 9.69 g
- Chickpeas: 2.6 – 6.6 g
- Peas: 1.9 – 4.97 g
- Taro root: 2.6 – 4.12 g
- Sweet Potatoes: 1.1 – 3.8 g
- Kidney beans: 1.5 – 2.6 g
- Parsnips: 1.1 – 2.1 g
- Sorghum flour: 1.6 g
As you can see, the range is often very broad. This can be due to the variety of vegetables and grains sampled and, again, the cooking (and cooling) methods used. To reach that higher end of the range, you’ll want to cook and cool your resistant starches as explained above.
There are several good Plant Paradox compliant options for store-bought foods that contain resistant starch. Here are a few of my favorites:
- Tortillas – almond and cassava
- Shirataki noodles – made with konjac root
- Coconut tortilla chips
- Plantain chips
- Taro root chips
- Cassava chips
- Cassava crackers
Other Prebiotic Fibers
While resistant starch is beneficial, it’s also not the only class of prebiotic fiber to include in our diet. Another good one is oligosaccharides, which are chains of 3-10 simple sugars linked together (also about 90% indigestible). Foods with oligosaccharides include chicory root, Jerusalem artichokes, onions, garlic, asparagus, and jicama. They have a slightly sweet flavor and are even included in one of my favorite sweeteners. (8)
You can also supplement with insoluble fiber to boost your prebiotic intake. A few of the ones Dr. Gundry recommends are psyllium husk, modified citrus pectin, and flaxseed.
It’s good to know which foods contain resistant starch and how to prepare them for maximal intake. But let’s not get carried away. If this resistant starch business is overwhelming to you, and you just want to eat already, there’s no reason to stress over eating things the right way. Plenty of people have had huge success on the Plant Paradox diet by simply following the Yes/No lists and taking a few supplements.
An occasional raw, unripe banana will not take years off your life. It’s also not necessary to cook and cool every single tuber you eat (imagine the meal prep!). A variety of raw, fermented, and cooked veggies, prepared a variety of ways, makes for a diverse microbiome. Do your best with the diet, and, if you’re in a place where you want to experiment with maximizing your resistant starch intake, you can employ the methods and suggestions in this post.