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Resistant Starch: Your Questions Answered

Posted By Mark Sisson On April 2, 2014 @ 8:00 am In Carbs,Gut Health,Nutrition | 168 Comments

Last week’s Definitive Guide to Resistant Starch [7] garnered a lot of attention. While the article covered a lot of ground, many of you had lingering questions and concerns about the topic: What is and isn’t resistant starch? How much resistant starch should I be eating? Why is resistant starch good for me? What is resistant starch again?

I don’t blame you; it’s a confusing one that appears, on first glance, to challenge some of the fundamental Primal ideas about food and nutrition.

Today, I’m going to answer as many questions from last week as I can. Hopefully it clears up most of the bigger questions.

Let’s get right to it:

Do the benefits of RS outweigh the negatives of rice, legumes, potatoes, etc.?

Great question.

Rice [8] and potatoes [9], yes. I’ve already spoken on both those subjects in previous posts, and my basic conclusion is that both rice and potatoes are relatively toxin-free sources of starch that an insulin-sensitive, sufficiently-active individual can likely consume in moderation without ill effect. For both foods, the negative effects come from the carb load they represent, which is simply too high for some people. But by cooking and cooling them, you reduce the carb load, reduce the glucose response, and improve your insulin sensitivity. In essence, any “negatives” are mitigated by the emphasis on resistant starch. If you have trouble with glucose tolerance, and you’re looking to drop weight, you should still exercise caution with these foods and heed the Carb Curve [10], but preparing them in a way that increases the RS content will only make them less problematic.

One note: potatoes are iffy for people with nightshade [11] intolerance. So there’s that to consider.

Legumes, I’m not sure. I strongly suspect that the health benefits ascribed to legumes are solely due to the prebiotic, RS effects, which interest me but are not the sole province of the legume [12]. But the fact remains that many people simply don’t tolerate legumes very well. It could be that some of the tolerance issues stem from disrupted gut flora [13] and introducing RS will ameliorate your troubles, but who knows? We’re still learning a lot. In the meantime, I’m not too interested in soaking [14] beans. There’s nothing essential about them, so long as we’re getting RS from other sources.

I’m a little confused…how does one go about adding RS in whole food form without doubling or tripling their normal daily carb intake? I can’t see eating 1-2 green bananas and a couple raw potatoes each day, in addition to normal amounts of carbs from veggies and fruit (I usually have one serving of fruit a day– berries, if possible) and still staying under 100-150 carbs. Please, enlighten me!

Believe it or not, you can easily eat green bananas without tripling your digestible carb intake. And that’s the key: you don’t digest these carbs, your gut flora do. An average large banana contains a hair over 30 grams of carbohydrate. If it’s green and totally unripe, the majority of that carbohydrate will be resistant starch that your body does not digest into glucose.

You’ll know you’re getting the good stuff when the banana is crispy and leaves a chalky aftertaste in your mouth. Pleasant, I know. But added to a smoothie, it’s actually quite nice. In fact, here’s a recipe I’ve been playing around with:

  • Cup of milk (coconut [15], almond, cow, goat, etc)
  • Large green banana, peeled and sliced
  • Quarter teaspoon of vanilla extract
  • Quarter teaspoon of cinnamon [16]
  • Half teaspoon of honey [17] (may be unnecessary depending on the sweetness of your bananas)

I assume that the time of day you take RS does not matter?

It shouldn’t. Once you’ve established a healthy population of butyrate-producing gut bugs, they don’t need to be fed at a certain time every day. They’re quite malleable and adaptive, and they’ll also begin feeding on other fermentable fibers in your foods.

What is the reason to supplement RS instead of getting it from food? How much RS is “good enough” and how much real food would meet that amount?

Supplemental RS is just easier, and most of the research in support of it has used supplemental RS-rich powders – so we know it works. But real food probably works even better since it comes with vitamins, minerals, and polyphenols (which have prebiotic effects in their own right), and it most closely resembles the way our early ancestors consumed RS.

Let’s see. If you can work your way up to between 30 and 40 grams of RS, whether from food or from powders, you’ll be in a good place. That’s the dose used in much of the research, and it’s where butyrate production is maximized.

What does that look like in food form?

600 grams of baked, then cooled, potato has around 25 grams [18]. You can even lightly heat the potato after it’s been cooled and retain the RS.

1 large (8 inch) green, fully unripe banana has somewhere between 20-25 grams. A large green plantain has about 50 grams. Not the most palatable, but it’s doable, especially if you slice into discs and dehydrate into chips. A smoothie masks it well, too.

Any idea if heating the potato starch (like using it as a thickening agent in soups/stews) negates its RS function?

Yes, the RS will be completely negated. Sorry. It does make a good thickener [19], though.

Cooked and cooled rice – as in sushi? Or does the vinegar somehow negate the benefit of the resistant starch?

Yes, cold sushi rice will contain RS. Good sushi restaurants generally keep their rice at room temperature, though, so I’m not sure you’ll get the retrograde RS effect unless you go for grocery store deli case sushi. And hey, I actually like that stuff, so there’s no shame in eating it. Just avoid gas station sushi if you know what’s good for you.

Vinegar shouldn’t affect it either way. Vinegar does reduce the blood glucose response [20] when consumed with carb-rich foods, so it might be a nice supplement in its own right if that’s an effect you’re after.

So that pizza crust recipe has mostly tapioca starch/flour (same) in it. (Also, not Potato Starch–potato flour) If I make the crusts and freeze them and then reheat and eat, would the RS still be usable? Same as the potatoes and rice I would think. So perhaps that is a go on the RS.

I don’t think it works like that. For retrograde RS to form, it has to be in its whole form – potatoes, not potato starch; cassava, not tapioca starch; rice, not rice flour.

Question about “cooked and cooled” – what the heck does that mean? So, I cook it, and cool it. Does that mean I have to eat it cold to get the resistant starch? If I zap my bowl of bean soup and rice that came out of the fridge, when does it lose the resistance to digestion?

Retrograded RS (cooked and cooled) is maintained during subsequent heating. You can even heat it and cool it once again to create even more RS. So you don’t have to eat it cold, though I would advise against re-heating a cooked and cooled RS source into oblivion. Keep the heat relatively low.

Should the carbohydrates from resistant starches (for example, a cooked and cooled potato) still be counted in daily consumption if it is not digested?

Some of it should still be counted, because not all – or even most – of the starch is resistant. Most of it is good old digestible glucose. But you can subtract the 4-5 grams of RS from the 21 grams total starch in every 100 grams of cooked and cooled potato. Not bad, eh?

And remember, it’s not that the 4-5 grams become inert, useless matter passing through your body. They are bioactive, just not with the biology of the host. They turn into fatty acids that fuel your colon and improve your ability to tolerate the digestible glucose you consumed along with them.

Is just eating Pistachio’s (or other seeds) enough RS to do the trick?

Probably not. To hit the 30-40 grams of resistant starch that maximizes benefits in most trials with pistachios would require a lot – of money, of calories, of shelling. 100 grams of roasted pistachios has around 3.5 grams of RS. That may be in the shell, and raw pistachios may have more, but either way it’s not a huge amount. Not bad, not great. The beauty of the less calorically dense RS sources is that they allow a more varied diet. It’s nothing to add a couple tablespoons of potato starch to your diet.

That said, pistachios are potent prebiotics. One recent study [21] found that they increased butyrate-producing bacteria in the colon, outperforming almonds. You should definitely eat pistachios, but I think you should also eat other more concentrated sources of RS.

That’s the beauty of it all: it’s not a competition! We can eat pistachios and other things at the same time without disrupting the effectiveness of either.

Question: would hummus fit the bill as cooked & cooled legumes?

Yes, hummus seems to qualify even though it’s not Primal [22]. According to the PDF [23] from last week’s post, 100 grams of hummus has 4.1 grams of RS. Hummus made from soaked chickpeas will have more than hummus made from canned chickpeas, however.

What would be the best way to gradually incorporate RS into the diet for a person that has gut inflammation with chronic bloating?

You need probiotics [24]. And in your case, I doubt yogurt [25] or even kefir [15] will be sufficient. Try something soil-based, as in the same types of probiotic organisms that Grok [26] was getting on a regular basis simply from living. These are likely the microbes to which our guts are evolutionarily accustomed.

Primal Flora [27] works (worked for me with RS!); it provides a high dose of two specific soil-based strains that have been shown to be helpful in clinical trials. You could also go more broad-spectrum, with more soil-based strains but lower concentrations.

Start really, really, really small with the RS. If you’re going with the unmodified potato starch, start with 1/4 to 1/2 a teaspoon. It will look like almost nothing. Increase it by 1/4 tsp slowly as comfort allows.

If that doesn’t work – but I imagine it would – and your gut is really compromised, I suggest trying Dr. BG’s gut healing protocol [28]. It involves probiotics, prebiotics, and a number of other, more drastic but potentially necessary steps. The good doc is a bit wild, but in a good way. Just read her stuff at least twice and you’ll figure it out. Reading it out loud seems to help, too. She certainly has a way with language!

Does this mean I can start eating sushi and potato salad??!

Well, you can choose to eat anything you want, of course. That’s never changed. What this does indicate is that those foods, when cooled, have unique effects, different than if you were to eat a bowl of hot steamed rice or a large baked potato fresh from the oven.

The preponderance of evidence suggests that the potato salad and the cold sushi rice will result in a lower blood glucose response [29] and feed the helpful critters in your gut – both good things. But before you go digging into that store bought potato salad on a regular basis, consider avoiding the seed oils and making your own. I’m a fan of lemon juice, olive oil [30], salt [31], and fresh herbs [32], myself. I can rarely be bothered to make my own mayo [33], although that’s also a good option.

Anyone have a recipe using raw potato starch that can be easily incorporated into a primal/paleo diet (meat, eggs, veges, occasional fruit)? I don’t do smoothies, nor do I do fruit juice or yogurt.

Aside from smoothies, sparkling water is the best vehicle I’ve found for potato starch. The bubbles seem to enhance the dispersal of potato starch granules into the medium, even without a blender. Just a fork or even a quick stir with your index finger is enough to get it completely mixed in.

So what to use? Bob’s Red Mill Potato Starch or Bob’s Red Mill Tapioca Flour?

Potato starch seems to be the most reliable way. From reading the comment sections on blogs and posts on various forums, the digestibility of tapioca starch/flour varies from person to person. Many people seem to get elevated blood sugar after taking a tablespoon or two of the tapioca, whereas potato starch is almost invariably indigestible.

Can the potatoes be fried in lard and then cooled? I would rather try a yummy food source then a powder.

A few weeks back, I described my method for foolproof, easy crispy root vegetables [34]. You pre-bake them and store in the fridge. This increases the RS content of the potato. When you’re ready to fry them, simply peel the skin, cut them up into the desired shape (cube, fry, etc), and lightly pan fry them in the fat [35] of your choice. Lard [36] is a great option. Since they’re already cooked, you don’t need a lot of heat or a lengthy cooking time, and the RS is preserved.

If we’re taking probiotics without RS as well – what is happening? The bacteria in the probiotics are starving? But don’t they eat other stuff besides RS? Sorry, I know I sound like a boob, but – I’m still a little confused.

No, the probiotics can still help, by partial colonization. But for the best results, you’ll want to provide food so that the probiotics have more lasting power and can hitch a ride into the colon where they do the most good. Feed the animals; they aren’t bears and it’s not Yellowstone! It can be resistant starch and/or any other prebiotic fiber. The point is to feed them stuff they can eat, thrive on, and ride on.

RS fits the bill.

One more question – how does this need for RS fit into the Grok-lore? What did our Paleo ancestors do that we aren’t doing?

As I’ve written before [37], wild tubers, roots, and other underground storage organs are frequently highly fibrous with lots of indigestible starch. That’s what Grok would have encountered, not the smooth, starchy goodness of a Russet potato, which had to be selected for by the experienced hands of agrarian tuber breeders.

We can’t all eat dirt-encrusted cattails [38] rich in resistant starch, but we can approximate the effects with modern tools. Taking soil-based probiotics and emphasizing preparation methods that maximize resistant starch content is, by all accounts, an extremely Primal and biologically-appropriate way to emulate one important aspect of our evolutionary metabolic environment.

Any thoughts on the resistant starch found in Quest Bars? Quest Bars contain isomalto-oligosaccharides. The makers claim this is a resistant starch.

It’s not a resistant starch per se, but rather a prebiotic [39] fermentable fiber. Studies indicate [40] that while its consumption does improve constipation and increase production of the short chain fatty acids (SCFAs) propionate and acetate, it does not increase production of the most beneficial SCFA, butyrate.

Is consuming RS the only way to feed our gut?

No, definitely not. Other prebiotic substances matter, like various plant fibers (inulin, pectin), dark chocolate, and even connective tissue (yes, animal fiber [41] – the crunchy gristle and cartilage too many people discard). With a Primal eating plan rich in plants and whole animals [42] (including bones [43] and broth [44]), you should be getting plenty. But resistant starch is an important, unique prebiotic that makes feeding our gut a whole lot easier and more effective.

That’s it for today, folks. Thanks for reading!

Prefer listening to reading? Get an audio recording of this blog post, and subscribe to the Primal Blueprint Podcast on iTunes for instant access to all past, present and future episodes here [45].


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[7] Definitive Guide to Resistant Starch: http://www.marksdailyapple.com/the-definitive-guide-to-resistant-starch/

[8] Rice: http://www.marksdailyapple.com/is-rice-unhealthy/

[9] potatoes: http://www.marksdailyapple.com/potatoes-healthy/

[10] heed the Carb Curve: http://www.marksdailyapple.com/the-primal-carbohydrate-continuum/

[11] nightshade: http://www.marksdailyapple.com/nightshades/

[12] legume: http://www.marksdailyapple.com/beans-legumes-carbs/

[13] gut flora: http://www.marksdailyapple.com/gut-flora-inflammation/

[14] soaking: http://www.marksdailyapple.com/soaking-seeds-and-nuts/

[15] coconut: http://www.marksdailyapple.com/homemade-coconut-milk-kefir/

[16] cinnamon: http://www.marksdailyapple.com/health-benefits-cinnamon/

[17] honey: http://www.marksdailyapple.com/is-honey-a-safer-sweetener/

[18] has around 25 grams: http://www.eurekalert.org/pub_releases/2013-04/fi-rsc042513.php

[19] thickener: http://www.marksdailyapple.com/low-carb-thickener/

[20] reduce the blood glucose response: http://www.ncbi.nlm.nih.gov/pubmed/16015276

[21] study: http://www.ncbi.nlm.nih.gov/pubmed/24642201

[22] not Primal: http://www.marksdailyapple.com/is-it-primal-8-foods-scrutinized/#axzz2xhEctMjJ

[23] PDF: http://freetheanimal.com/wp-content/uploads/2013/08/Resistant-Starch-in-Foods.pdf

[24] probiotics: http://www.marksdailyapple.com/whats-up-with-your-gut-beneficial-bacteria-and-good-digestive-health/

[25] yogurt: http://www.marksdailyapple.com/yogurt-mania/

[26] Grok: http://www.marksdailyapple.com/about-2/who-is-grok/

[27] Primal Flora: http://www.primalblueprint.com/product/Primal_Flora/Supplements

[28] Dr. BG’s gut healing protocol: http://drbganimalpharm.blogspot.com/2013/11/how-to-cure-sibo-small-intestinal-bowel.html

[29] lower blood glucose response: http://www.marksdailyapple.com/sprints-blood-sugar-resistant-starch-carbs-pufa-coconut-oil-cycling-chronic-cardio-morning-sickness/

[30] olive oil: http://www.marksdailyapple.com/is-your-olive-oil-really-olive-oil/

[31] salt: http://www.marksdailyapple.com/salt-what-is-it-good-for/

[32] fresh herbs: http://www.marksdailyapple.com/health-benefits-herbs/

[33] mayo: http://www.marksdailyapple.com/coconut-shrimp-and-chive-mayonnaise/

[34] described my method for foolproof, easy crispy root vegetables: http://www.marksdailyapple.com/is-gently-cooked-food-better-for-you/

[35] fat: http://www.marksdailyapple.com/yet-another-primal-primer-animal-fats/

[36] Lard: http://www.marksdailyapple.com/three-dishes-with-three-animal-fats-lard-tallow-and-duck/

[37] written before: http://www.marksdailyapple.com/starch-fallback-food-or-essential-nutrient/

[38] cattails: http://www.marksdailyapple.com/bread-grains-30000-years/

[39] prebiotic: http://www.marksdailyapple.com/prebiotics/

[40] indicate: http://www.ncbi.nlm.nih.gov/pubmed/11294172

[41] animal fiber: http://caloriesproper.com/?p=4488

[42] whole animals: http://www.marksdailyapple.com/everything-but-the-squeal/

[43] bones: http://www.marksdailyapple.com/bone-marrow-recipe/

[44] broth: http://www.marksdailyapple.com/bone-broth-nutrients-and-alternatives-to-agriculture/

[45] here: https://itunes.apple.com/us/podcast/marks-daily-apple-best-2014/id789935889?i=319256178&mt=2

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