Some months ago I got interested in the fact that people were toying with the idea of eating mostly just potatoes for a period of time for weight loss. So I tried it, blogged about it, entertained it for a few weeks, dropped about 13 pounds to verify it works (probably because it's hard to eat enough potatoes to maintain weight). But I just quickly got tired of potatoes. Not so at all with my milk & kefir deal that's into its seventh week, stronger than ever, and now I'm really doing a lot of tweaking of the essential magic of the thing. But details on that are for a different day and newsletter issue.
One thing that cropped up and that's been a new tweak in my milk & kefir escapades: resistant starch. It was a commenter, "Tatertot," who'd done all the yeoman's work on the deal, so I asked him to put it all together for us.
So here's Tatertot.
Last fall, I was toying around with the Potato Hack and mentioned it on Paul Jaminet's Perfect Health Diet blog. Paul mentioned that part of the effectiveness of the Potato Hack undoubtedly was due to the butyric acid and short-chain fatty acids (SCFA) from the resistant starch in the potatoes.
This got me thinking about resistant starch (RS). I had heard of RS before, but didn't know much about it. I did a few Google searches, and the more I read, the more I liked. There were well-studied correlations between RS intake and colon health, improved cholesterol, better glucose control, weight loss, hunger abatement, and increased vitamin and mineral absorption.
I learned that scientists first 'discovered' RS in the 80's. Since then, numerous studies have been done on the effect of RS in animals and humans. One of the first articles I read on RS was written in 2008. Please read for a quick primer on RS. Done? OK, moving on.
At first, people told me I was wasting my time with RS. Afterall, they said, "RS is nothing more than Type III fiber, right after soluble and insoluble. We got over our obsession about fiber when we got over eating Kashi...It's not that it's bad for you, just not necessary; and, If it's butyrate you want, just eat butter—or put it in your coffee!—it's loaded with the stuff." I almost gave up my quest when I came across Dr. Eades' article bashing RS: He concludes in the article, "This brief discourse should put you off of resistant starch even without knowing what anti-nutrients are (resistant starch is an anti-nutrient), why they’re there and what they do. We’ll save that for a later post." Then there was this great back-and-forth on Mark's Daily Apple.
Luckily, I found tons to support the intake of RS from a number of other sources, so I kept looking.
Most scientists used 20-50 grams RS per day in their human studies. Most recommendations are for the ingestion of 20-40g/day for maximum benefit, and there seems to be an upper limit of about 60g where it stops being effective, and a lower limit of about 20g where it has little effect.
My next step was to target RS in the 20-60g/day range from common foods...this proved difficult.
I learned there was a bit of RS in cooked and cooled rice, like sushi rice, but only a small amount, like 5g per cup.
An average-sized raw potato contains about 50g RS. When cooked it contains between zero and 5g, depending on cooking methods. The RS found in raw potatoes swells and bursts as temperatures approach 160 degrees F, turning the RS into rapidly digestible starch. The highest RS in cooked potatoes is in potato chips and french-fries—foods most paleo eaters wisely avoid because of the oils used.
When cooked potatoes are cooled, the starch undergoes a process called 'retrogradation' where the rapidly digestible starch is converted back into RS. The amount of RS in a cooked and cooled potato is approximately 8g.
Another source I found for easily accessible RS was green bananas. A medium-sized, very green banana contains 15g RS. As it ripens, the RS goes to zero. A big problem is that very green bananas taste like crap! They can be eaten, but not really enjoyed.
Legumes such as kidney beans contain a fair amount of RS, nearly 10g per cup. Once again, most paleo eaters wisely avoid legume consumption due to possible anti-nutrients and harmful compounds. Still, I don't hide from the occasional serving of beans—I just don't make them a staple food.
Unripe plantains are about 75% RS by weight. Unripe plantains are worse than green bananas and completely inedible. I did, however, find that when dehydrated and salted, they are very palatable. They taste just like a Saltine cracker and provide about 100g of RS per plantain.
Another source of RS I looked into was Hi-Maize Corn Starch. This product is made from specially bred corn with a high RS content. It's widely added to baked products to increase the RS content. My paleo leanings kept me from trying this out.
The latest and probably most promising product I've found is unmodified (raw) potato starch (RPS). RPS is widely noted as containing 78% RS by weight. Bob's Red Mill sells potato starch for under 15 bucks for 5 pounds. There may be other suppliers, if so, make sure you are buying 'unmodified' potato starch. Potato Starch is often modified for industrial purposes—you don't want that!
Edibility-wise, potato starch is not bad. It mixes well with any liquid and has no real taste and is not gritty, mealy, or pastey. I've eaten up to 4TBS (48g), which is 30-35g of RS, on an empty stomach with no digestive problems. I think it is a very good addition to your arsenal of RS foods.
So, after months of research, it's come down to this: I eat potatoes almost every day, cooked in a variety of ways, a few raw slices, and lots of cold potatoes. I eat sushi when I can, beans on rare occasion, and I keep a baggy full of dried plantains on the counter to snack on. When I buy bananas, I get the greenest ones I can find. Sushi is eaten guilt free, especialy with raw fish and seaweed. I will eat legumes from time to time if thoughtfully prepared to remove toxins. I also keep a container of potato starch on the counter and am finding all kinds of ways to use it--in smoothies, milk, kefir, mixed with water and eaten with berries and mashed bananas, or just mixed with water and drank.
In the several months I've been trying to get 20-60g/day RS, I have witnessed a lowering of fasting blood glucose from the 110-120 range to the 90's, hdl cholesterol increased from 35 (in Nov 12) to 59 last week, ldl lowered from 150 to 130, and triglycerides went from 60 to 50. Whether these improvements are soley from the RS is hard to say, but at least they didn't go in the other direction! It's hard to pin down the contributions of a healthy gut, but I think it's a worthwhile endeavor to target an increase in RS, especially for people who are pre-diabetic or have high cholesterol.
An experiment I did recently with potato starch told me all I need to know. I have been tracking my fasting blood glucose and post-prandial resonse to carbs with a OneTouch glucose monitor. I know that a potato with 40g carbs will cause a PP glucose spike of over 175 at 1 hour and return to normal at 3 hours. I drank 44g of potato starch mixed with water on an empty stomach and checked my glucose level every 15 minutes...I never saw a rise in BG more than 5 points above my fasting level. This proved to me that potato starch causes absolutely no glycemic load. Furthermore, 4 hours later, I ate a large, plain potato and found that my 1 hour PP glucose level was under 140 and returned to normal in less than 2 hours! Thus proving to me that RS has a powerful 'Second Meal Effect" as described here. I think it will turn out that as far as Low Glycemic Index foods are concerned—raw potato starch is the lowest!
I'm hoping that Richard can get the word out and explore RS on his blog and get some interest going. Here are a few studies to look at concerning RS, but a quick Google, Google Scholar, or PubMed search for Resistant Starch + terms like obesity, diabetes, potato starch, or gut health will turn up hundreds of studies.
- A compilation and overview of numerous studies
- Starches, Resistant Starches, the Gut Microflora and Human Health
- A look at RS in the Chinese diet, lots of food charts and comparisons with other diets
- Search for RS on Perfect Health Diet website
It's been two weeks or so since, at Tatertot's suggestion, I've usually been taking 4 tablespoons of Bob's Red Mill Potato Starch per day, stirred into milk or kefir (actually quite pleasant taste & texture, for me). The most prominent effects I've noticed (I don't prick my fingers, sorry):
- Increased satiation. I go quite longer before wanting more milk, depending on whether the last time was with the potato starch or not.
- TMI aspects are very, very good.
- Prolonged sleep. Even though I'm a pretty good sleeper, I'm used to a few short stirs and wake-ups per night; but if I take 2T of the PS in a glass of milk before bed I have bouts of going 5-6 hours without a single wakeup.
- Weirdest of all: I have these long-ass, complex narrative dreams about current stuff in my life, instead of the more common, crazy-assed, out-of-nowhere dreams that seem anxious and go on and on in a continuous loop, if you know what I mean. I suspect this is a consequence of #3, and not a direct link to whatever the PS/RS is doing to colonic gut flora, though I don't rule it out.
OK, dat's all folks. Giver 'er a shot and oh, BTW, RS yields only 2-3 calories per gram, not 4.