Resistant Starch: Super Food

March 28, 2016

Resistant Starch - Secret Super Food?

Reference:  AJCN, 2005,, International Jr Obesity

Have you heard of resistant starch? It's been making the rounds and has even sparked some books. In its simplest explanation, it's starch that isn't easily digested. There are actually four different categories that have been sorted out so far. 1) starches attached to the indigestible cell wall of beans, seeds and some grains. 2) Starch in plantains, potatoes and bananas that is indigestible prior to heating and cooking because of its high content of amylose. Heating it makes it bio-available. 3) Retrograded starch. This type becomes resistant on cooling after cooking. This can be found in potatoes, some beans and grains. 4) The fourth type is industrially made by modifying corn starch.

It's what resistant starch (RS) does in the body that makes it interesting. Starch is essentially long chains of glucose. Glucose is a molecular ring of 6 atoms which has six binding sites for attachment. When glucose molecules are attached to each other at the #1 and the #4 sites, they line up like beads and make a very tight package that is not easily digestible. This is called amyloseand is about 20% of many starches. This is the resistant stuff. 80% of starch has glucose branches every 20-30 molecules making a very branched chain, and enzymes can get in those branches and break them apart. This is called amylopectin, is very digestible and releases sugar into the blood vary rapidly. This is the stuff that makes potatoes, bananas and rice quite high in digestible starch.

Now, resistant starch turns out to do interesting things in your gut. It encourages the growth of different bacteria. Those bacteria produce n-butyrate, the main food of colonic cells. . In fact, they are the main source of n-butyrate. Did you get that? The right bacteria in your gut make the food that your colonic cells depend on. Your colonic cells aren’t fed by the nutrients in your blood as much as by energy from n-butyrate. Totally counterintuitive!

But that isn’t the half of it. Resistant starch improves insulin sensitivity. That is opposite to what you would expect. How does that work? It's too complicated to dissect here but leave it to say, those short chain fatty acids also get into your blood, and participate in a whole cascade of effects, most importantly being more insulin sensitivity. Lower levels of insulin basically make it easier for fat cells to open up and share their calories. When that happens, you aren't as hungry because you get calories from your fat. That's called weight loss. Did you get that? Weight loss! RS increases magnesium absorption. Many folks report better mood and better sleep. Hmmm. Imagine that. The hypothesis is your gut makes serotonin, and when your gut is well fed, that makes you feel better.

Are there bad effects of RS? Well, yes. Some folks complain of bloating and gas. Some say they gain weight. That makes sense too when you consider that RS is only part of potatoes and bananas. When you eat the whole potato, you also get 80% amylopectin, the easily digested sugar.

WWW. What will work for me. I'm totally fascinated with the concept that our intestinal bacteria feed our colon, and they get their food from RS. I know we can measure butyrate on stool tests, and just about everyone is low. I want to watch this story and figure out how to get some into my diet without gaining weight or increasing my bad blood lipids. I'm not out eating more potatoes quite yet, but I did try a cold one yesterday.

Pop Quiz

1. Resistant starch is basically chains of glucose that we don't have enzymes to digest, but our colon's bacteria do. T or F                                   Answer:   That's it in a nutshell. 

2.  There are beneficial bacteria in your colon that digest RS and make it into gas that feeds your colon cells. T or F                    Answer:    Oops, you missed the point. False. Those bacteria make butyrate, a short chain fatty acid, that feeds your colon. It's not a gas. But, some folks do feel gassy when they start eating RS.

3. A clear benefit of RS is that your insulin sensitivity goes up, which means your insulin levels go down, which is good. T or G                          Answer:   True. Fascinating. Not intuitively obvious.

4. Better sleep and calmer mood may be a side effect of RS. T and F                       Answer:  Yup. Might be worth a try if you want to buy the pure stuff and add that as a supplement to your diet.

5. Resistant starch has been well studied and fully characterized. T or F                 Answer:  Not at all. This story is just starting. There is no obvious money in it because it's already out there. If it were a pill that could be patented, you would see it on the evening news and being sold for big bucks. As it is, its benefit is still being studied and no one hears much about it.