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Forming RS3 Resistant Starches

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I'm curious if there is an ideal way to form retrograde resistant starch (for lowering the glycemic index of starches and increasing the fiber-like content for prebiotic purposes.)

 

I found this recipe: http://www.rsc.org/chemistryworld/2015/03/low-calorie-healthy-rice-resistant-starch

 

In that article, they recommend adding coconut oil to cooking water used for rice, simmering for 40 minutes, refrigerating for 12 hours, oven drying for 2.5 hours, and finally re-heating via microwave before consumption.  This seems like quite a bit of prep to cook some rice.  I'm not sure if they're recommending that the oil / saturated fat be cooked into the rice, or if they were draining the water such that little coconut oil ends up in the rice, like you might cook noodles.

 

I'm curious if this would work well with other fats (olive oil?) to reduce saturated fat content, or if the fat is even necessary for this to work.  If the fat is a key element for the process, would it be better to toss the boiled starch in EVOO after it's cooked or mash it into a potato before cooling (it seems like it would just float over the simmering water and partially oxidize) ?  Is the 2.5hr drying step a key aspect of this process (what temp?)  Am I missing out on a lot of potential RS if I just throw rice in a cooker or boil a potato, move it to the fridge (or maybe the freezer is better?), then heat it back up?  Is it better to eat this starch cold rather than reheated to better preserve RS content?

 

Apologies for all the questions :Dxyz -- I'm just trying to wrap my head around the basic formula here and tease out which factors might be the most effective and applicable to other starchy foods.

Edited by sirtuin

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Hi Sirtuin:

 

I have been watching the discussions here lately about blood sugar responses to food intake and the importance of moderating them, and have been expecting someone to pipe up and put the contrary case.  Since no one else seems to have done so, I guess it will have to be me who plays the part of devil's advocate - a part I often can find enjoyable(!)

 

Probably two to three years ago, when the email list was in widespread use, I recall a fairly comprehensive discussion that in mice, those which exhibited a remarkably poor response to a glucose tolerance test, but were otherwise metabolically healthy, calorically restricted with fasting insulin and fasting glucose both low, and non-excessive levels of HbA1c, lived somewhat LONGER than those showing very tight blood sugar control in response to food.

 

I don't think I am dreaming about that discussion.  And if I am correct, is our immediate blood sugar response to food intake something we should be paying a lot of attention to?  Certainly, *fasting* glucose should be good, and fasting insulin perhaps especially so, and HbA1c at acceptable levels (logically, somewhat higher in those with less tight blood glucose control).  But given the results of the mouse experiments I believe I recall, mentioned above, is the short term profile of our blood glucose response to food of major significance?  Just asking, and giving the devil some exercise. 

 

Rodney.

 

==========

 

"The unverified conventional wisdom is almost invariably mistaken."

Edited by nicholson

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Hi Sirtuin:

 

I have been watching the discussions here lately about blood sugar responses to food intake and the importance of moderating them, and have been expecting someone to pipe up and put the contrary case.  Since no one else seems to have done so, I guess it will have to be me who plays the part of devil's advocate - a part I often can find enjoyable(!)

 

Probably two to three years ago, when the email list was in widespread use, I recall a fairly comprehensive discussion that in mice, those which exhibited a remarkably poor response to a glucose tolerance test, but were otherwise metabolically healthy, calorically restricted with fasting insulin and fasting glucose both low, and non-excessive levels of HbA1c, lived somewhat LONGER than those showing very tight blood sugar control in response to food.

 

I don't think I am dreaming about that discussion.  And if I am correct, is our immediate blood sugar response to food intake something we should be paying a lot of attention to?  Certainly, *fasting* glucose should be good, and fasting insulin perhaps especially so, and HbA1c at acceptable levels (logically, somewhat higher in those with less tight blood glucose control).  But given the results of the mouse experiments I believe I recall, mentioned above, is the short term profile of our blood glucose response to food of major significance?  Just asking, and giving the devil some exercise. 

 

Rodney.

 

==========

 

"The unverified conventional wisdom is almost invariably mistaken."

I'm still unsure where the ideal targets might be for post-prandial glucose (or if post-prandial glucose is a concern when A1C / Fasting glucose looks fine.)  Perhaps a little glycation and brief high levels of blood sugar provides for a hormetic stress that improves longterm health / survival.  Although, I don't like to see mine up in the 160 to high 170 mg/dL range for over an hour, as I don't see that referenced much for exceptionally healthy non-diabetics -- if this isn't a concern, then perhaps my higher-fat low-carb low-GI diet with the occasional unexpected high-GI ripe fruit + high-GI starch over low-activity, which my body seems unprepared to handle in that circumstance, is ideal for longevity purposes (as there's minimal glucose provided in the diet / minimal insulin required most of the time.)  In the other GI thread, I would love to hear counter-arguments that point to peak post-prandial glucose numbers in the 140/mg+ range as being healthy, if not beneficial.

 

On this topic, I do think RS does provide some interesting prebiotic benefits, as well as appetite suppression (useful for CR?), increased insulin sensitivity, improved blood lipids, and lower insulin levels.

 

http://chriskresser.com/how-resistant-starch-will-help-to-make-you-healthier-and-thinner

http://drbganimalpharm.blogspot.com/2014/06/contupdate-2-rs2-and-rs3-are-not.html

http://ajcn.nutrition.org/content/82/3/559.long

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296917/

 

I'm curious which factors might best increase and preserve that content in starches, as this could be another useful trick:

 

This was an interesting study using Konjac glucomannan (I do enjoy shirataki noodles / japanese dishes with konnyaku):

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397344/

Edited by sirtuin

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Sirtuin,

 

Here is the best discussion I could find on the apparently pretty exaggerated media claims about the potential to boost resistant starch in rice through cooking with a small amount of oil and letting it cool overnight. Basically the effects were marginal (10-12% fewer available calories relatively to normally cooked rice), seemed dependent on the particular cultivar of rice used, and it was a single small & non-peer reviewed study. Here is the original popular press report from the American Chemical Society annual meeting on the study. So it doesn't seem to me like that big a win. Having said that, as a matter of course, I cook most of my starches (including rice, barley, legumes and sweet potatoes) el dente to avoid breaking down too much starch (not to mention I like them with a little more texture, not mushy), and I cook them in big batches and freeze them for later use. While I don't use oil in cooking, I suspect my way of preparing & storing them does increase their resistant starch contents. 

 

 Rodney,

 

Regarding impaired glucose tolerance and CR. Luigi Fontana found in [1] that a significant subset of the CR Society folks (including me, but more generally the ones who were the most calorie restricted) displayed an impaired glucose response to an oral glucose tolerance test (OGTT). In the paper, he points to the fact that this is also seen in CR'ed rodents, despite the rodents (and humans) being otherwise healthy and long-lived.

 

We've speculated what this result might mean. Perhaps given the limited calories CR'ed organisms (human or rodent) ingest, the low GI nature of our diet, and our high insulin sensitivity, our pancreas may have downregulated its ability to produce a lot of insulin on short notice in response to a huge bolus of glucose like one ingests during an OGTT - resulting in what appears to be poor glucose control. Alternatively, some of us worried about another possibility, that insulin producing beta cells in our pancreas may be dying due to a "use it or lose it" dynamic, perhaps pushing us towards a condition like type 1 diabetes...

 

But I don't believe (or recall) anyone suggesting that large post-meal glucose excursions are healthy or desirable. In fact quite the contrary - as I recall Michael Rae once did a post giving strong evidence that the negative effects of elevated glucose are non-linear, with large spikes accounting for a disproportionately high contribution to the negative health effects of glucose, like glycation. 

 

Now it might  be argued that a transient spike, say towards 120-140 mg/dl, and perhaps attenuated by post-meal exercise if necessary to help bring it down effectively, might be beneficial for keeping one's pancreas 'in shape', i.e. preventing its ability to produce insulin when necessary from atrophying. But that would be speculation. 

 

--Dean

 

--------------

[1] Age (Dordr). 2010 Mar;32(1):97-108. doi: 10.1007/s11357-009-9118-z. Epub 2009 Nov

11.

Effects of long-term calorie restriction and endurance exercise on glucose
tolerance, insulin action, and adipokine production.

Fontana L(1), Klein S, Holloszy JO.

Author information:
(1)Washington University School of Medicine, St. Louis, MO 63110, USA.
lfontana@dom.wustl.edu

Calorie restriction (CR) slows aging and is thought to improve insulin
sensitivity in laboratory animals. In contrast, decreased insulin signaling
and/or mild insulin resistance paradoxically extends maximal lifespan in various
genetic animal models of longevity. Nothing is known regarding the long-term
effects of CR on glucose tolerance and insulin action in lean healthy humans. In
this study we evaluated body composition, glucose, and insulin responses to an
oral glucose tolerance test and serum adipokines levels in 28 volunteers, who had
been eating a CR diet for an average of 6.9 +/- 5.5 years, (mean age 53.0 +/- 11
years), in 28 age-, sex-, and body fat-matched endurance runners (EX), and 28
age- and sex-matched sedentary controls eating Western diets (WD). We found that
the CR and EX volunteers were significantly leaner than the WD volunteers.
Insulin sensitivity, determined according to the HOMA-IR and the Matsuda and
DeFronzo insulin sensitivity indexes, was significantly higher in the CR and EX
groups than in the WD group (P = 0.001). Nonetheless, despite high serum
adiponectin and low inflammation, approximately 40% of CR individuals exhibited
an exaggerated hyperglycemic response to a glucose load. This impaired glucose
tolerance is associated with lower circulating levels of IGF-1, total
testosterone, and triiodothyronine, which are typical adaptations to
life-extending CR in rodents.

PMCID: PMC2829643
PMID: 19904628

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Last night, I had fresh boiled long-grain rice (lightly al dente) and measured post-prandial glucose with some EVOO mixed in -- +30m read 142 mg/dL, +45m read 122 mg/dL after a ~100g net carb meal.  Pretty good numbers, I suppose.

 

I then took a solid green plantain and boiled it for around 20m until soft, mashed it up with some dark chocolate + a little bit of coconut flour, and refrigerated it to eat with breakfast this morning (cold dinner leftovers.)  Eating breakfast after 20m of cycling with ~100g net carbs followed by cleaning (not sitting down afterward), +30m measured 94 mg/dL, and +45m measured 85 mg/dL.  Experimenting with slight variations on meal timing, I tried starting the meal with a piece of fruit (quick glucose to stimulate insulin and prepare for the glucose needs), followed by nuts / fats (to slow down starch digestion), followed by fibery vegetables and finishing with cooked + cooled starches mixed with fats (my chocolate plantain 'cake'.)  This level of optimization is probably way overkill, but I'm curious to peer further down into this rabbit hole.  It seems as though dinner is the ideal time to test theories as I seem particularly insulin sensitive with my morning regimen.

 

It seems like if I freeze steamed rice and move it to the fridge, I end up with very hard rice -- I'm wonder how the RS content compares here with freshly cooked + cooled rice with fats or how resistant this RS content is against reheating.  I've read multiple reheating + cooling cycles might form more RS (although this doesn't seem great for the oxidative status of the fat content.)

 

This is an interesting article on parboiled rice:

http://freetheanimal.com/2013/12/parboiled-nutritious-resistant.html

 

"Parboiled rice kernels should be translucent when wholly gelatinized. Cooling brings retrogradation whereby amylase molecules re-associate with each other and form a tightly packed structure. This increases the formation of type 3-resistant starch which can act as a prebiotic and benefit gut health in humans.

 
It has a low glycemic score of 38, compared with a high 89 for white rice"
 
This reduction in GI seems impressive to me as it only has 2 grams of fiber in an 81g carbohydrate serving.
Edited by sirtuin

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Cool results sirtuin! Thanks for sharing. Those plantain breakfast glucose results were quite impressive!

 

BTW - for anyone who wants the benefits of the resistant starch in unripe plantains (which is known to be one of the best sources of RS - see below), you can buy plantain flour on Amazon, but it is expensive. I buy it from Barry Farm for $4.10 per pound.

 

From here:

 

Cooked and cooled sushi rice has about 5 grams of resistant starch per cup. I will work my way up to 4 tablespoons (48g) of plantain flour per day, for about 32 grams of resistant starch.

 

--Dean

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Gracias!  It's been kind of fun tracking this stuff.  I wish I could just wear a comfortable wrist band that somehow monitored glucose / insulin / cholesterol, etc.  I found this interesting discussion:

 

https://www.paleohacks.com/potatoes/cooked-cooled-reheated-potatoes-resistant-starch-32970

"reheating rice, beans and potatoes does not harm the RS3, in fact, it increases it by driving more water out of the retrograded structure"

 

Although, there was also this discussion:

"It would seem that reheating cold cooked potatoes will reduce the RS3 (retrograded resistant starch) content slightly compared to their cold state. for refs google; "retrogradation is partly reversible" potato (but the RS3 will increase again if allowed to cool)"

 

Others yet mention that reheating to 130F is safe for maintaining RS content (which seems pretty low for practical re-heating purposes.)  I would imagine that a dry heat source like an oven at 350F would serve to increase the glucose content of the non-resistant starch content to drive up the GI.  Perhaps the old microwave is the ideal tool here for reheating and driving out moisture.  I couldn't find too much discussion on freezing vs refrigerating -- it seems like you want it cold but not frozen, and most of the action occurs within the first 12hrs of refrigeration.  I suppose the last piece to the puzzle is whether added fat is necessary or particularly beneficial over not adding fat to the starch.

Edited by sirtuin

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Sirtuin,

 

Others yet mention that reheating to 130F is safe for maintaining RS content (which seems pretty low for practical re-heating purposes.)... Perhaps the old microwave is the ideal tool here.

 

I agree. Here's what I do with my el dente cooked starch mixture. I package it in single day servings (250g = 280kcal) and then freeze them. The day before, I take one of the single servings out of the freezer and put it in the fridge to thaw. Then, at mealtime, I pop it in the microwave for 1min before eating it. This brings the temperature up to warm but not hot - I estimate around 125F.

 

--Dean

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Doing a little more research, I found a few more interesting resources.

 

http://forums.phoenixrising.me/index.php?threads/the-resistant-starch-challenge-is-it-the-key-weve-been-looking-for.26976/page-6

 

"The crystallinity of retrograded amylopectin is lost following re-heating to approximately 70°C, whereas temperatures above 145°C are required to remove crystallinity of retrograded amylose. This is a temperature well above the range used for processing of starchy foods. This implies that retrograded amylose, once formed, will retain its crystallinity following re-heating of the food."

 

"The retrogradation process begins at about 40 degrees F and is fully complete when the temperature drops to 17 degrees F. If you heat this potato back up, the retrograded starch actually gets stronger as more water is expelled. In fact, you can heat and cool it several times and with each cycle, more retrograded starch forms. When eaten, this provides a good meal for you AND your gut bugs. Win-win. This is the way humans cooked and ate for millions of years after we learned to cook food."

 

"So... there's no need to eat your RS3 cold, so long as heat with a dry approach and you don't reheat above 293ºF/145°C."

 

I found this interesting chart on the RS content in some common foods: http://freetheanimal.com/wp-content/uploads/2013/08/Resistant-Starch-in-Foods.pdf

 

Boiled Potato -- minimum: 0.2, up to 4.6.  Cooked & Cooled Potato -- minimum: 3.2.  Boiled / Frozen -- minimum: 5.71, up to 12.2.  Steamed & Cooled -- minimum: 5.8  Roasted & Cooled -- minimum: 19.2.

 

While a roasted potato has a higher-GI than a boiled potato, perhaps a roasted, frozen, and dry low-medium heat reheated potato would have more RS and a lower GI than a boiled / refrigerated / microwaved potato?

 

I found this discussion with a slightly different approach to forming RS in potato, which modifies the texture through the activation of some enzyme (PME) around 60-70C with a low-temperature blanching pre-treatment: https://www.paleohacks.com/starch/retrograded-potatoes-spike-insulin-less-4915

 

Although, I was also reading that sweet potatoes are "unusually rich" in beta-Amylase, accounting for ~5% of the soluble proteins, with activity increased via cold storage and peaking between that same 60-70C range, extending up to around 170F.

 

Then, digging around a bit more, there's this article which mentions RS5 is produced with starch-lipid complexes: http://lib.dr.iastate.edu/etd/12810/

Edited by sirtuin

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Hi Sirtuin and Dean!

 

I never eat potatoes, rice or grains, whether or not they have been cooked, frozen or otherwise treated to increase resistant starch content.

 

Exceptions:

 

(1)  Rarely -- about once every 3 months or so -- I eat a small piece of an organic raw sweet potato.

 

(2)  Orthodox Judaism requires that one eat some bread (possibly the vilest of starchy foods) every Friday evening and Saturday afternoon.  Here's how I've tried to work around that:

 

Trader Joe sells what it calls a "reduced carb tortilla".  The specs are (for each tortilla):

Calories: 45

Fat:  1.5g (zero saturated fat)

Carbs:  10g (Insoluble Fibre 6g; Soluble Fibre: 1g; Sugars: 0g. So subtracting: Starch:3g)

Protein: 4g.

 

Ingredients:  Water, Wheat Fibre, Wheat gluten, Whole Wheat Flour, Oat Fibre, High Oleac Sunflower oil, plus 2% or less of other ingredients (I'm too lazy to copy them :)xyz).

 

So, I eat one of these tortillas on Fridays, and on on Saturdays (they're marked Kosher).

 

  -- Saul

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I found a couple more interesting tidbits:

https://scholar.google.com/scholar_lookup?title=Resistant%20starch%E2%80%93A%20review&author=MG%20Sajilata

  • The best results were obtained @134C, with 4 heating / cooling cycles and a starch:water ratio of 1:3.5.
  • Lower temperatures and high water content results in type B configuration (more resistant to digestion / reheating.)
  • The yields of RS decrease in the presence of salts and sugars.
  • Maximum yields occur between 2 and 4d of cold storage after which they decrease.
  • Rice stored at –20C retrograded more than rice stored in the refrigerator.
The article does mention some concerns like cecal enlargement and pelvic nephrocalcinosis?
 
I also came across this article, which mentions some RS concerns (enhanced tumor growth / toxin absorption?): http://www.thepaleomom.com/2015/08/resistant-starch-its-not-all-sunshine-and-roses.html

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Hi Saul:

 

"  ....... bread (possibly the vilest of starchy foods)  ....  "

 

Vile is a pretty strong word.  It would be really helpful if you could explain the reasoning behind your above comment.

 

Do you mean, simply, that you personally do not like the way it tastes?  Or is there more to it than that?

 

I eat bread, consider it healthy, and very much enjoy it.  Didn't someone describe it as "The staff of life."  ?

 

I can certainly agree that it contains a lot of calories, and for which reason it may in significant part explain the survival of your and my ancestors, after they left Africa.

 

Thanks.

 

Rodney.

 

===============

 

"The unverified conventional wisdom is almost invariably mistaken."

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Hi Rodney!

 

I mean that bread is mostly empty calories -- and yes, also, I don't like bread.

 

I gave up eating bread in my teens (I'm 76.5 yo now :)xyz) -- way before I ever heard of calorie restriction.  I regraded bread -- and still regard it -- as junk food.

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This was another interesting tidbit:

http://www.life-enhancement.com/magazine/article/3265-new-technology-doesnt-have-to-be-expensive-or-complicated

 

It's mentioned that the addition of MCT oils specifically in coconut oil increase resistant starch formation in rice.  (I'm curious if C8-C10 would suffice, or if Lauric acid is particularly useful here.)  The RS concentration ranged from 0.3 - 4.65% (which is an average of 2.5%) after cooking with the oil and then cooling.  Yet, I've read that simple cooled long grain rice has an RS3 content of 2.6%, without any oil (so, perhaps added oils are not necessary?)  It's interesting that a roasted and cooled Purple Potato seems to top the charts here at close to 20% RS3 -- http://drbganimalpharm.blogspot.com/2014/10/dont-eat-raw-resistant-starch-rs2-if.html.

 

It is estimated native Africans consume 40 to 60 grams daily RS3, and otherwise eat a relatively low 'fiber' diet of 15-25 g fiber daily.  They have some of the lowest colorectal cancer rates.

 

A few other interesting articles:

http://www.mdpi.com/2072-6643/4/6/425/htm

http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12143/full

http://www.sciencedirect.com/science/article/pii/S0308814697000253

 

Reading more about these starches, I found the changes in RDS / SDS (rapidly digested starch / slowly digested starch) via different preparation techniques and storage conditions interesting.  In the past, I basically viewed starch as glucose.  Fascinating stuff.

Edited by sirtuin

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