Getting Starch to Take the Path of Most Resistance

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How might beans, berries, and intact (not just whole) grains reduce colon cancer risk?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Resistant starch wasn’t discovered until 1982. Before that, we thought all starch could be digested by the digestive enzymes in our small intestine. Subsequent studies confirmed that there are indeed starches that resist digestion, and end up in our large intestine, where they can then feed our good bacteria—just like fiber does. Resistant starch is found naturally in many common foods, including grains, vegetables, beans, seeds, and some nuts—but in small quantities; just a few percent of the total. There are a few ways, though, to get some of the rest of the starch to join the resistance.

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta, and potato salad can be healthier than a baked potato. But the effect isn’t huge. The resistant starch goes from about three percent up to four percent. The best source of resistant starch is, therefore, not from eating cold starches, but from eating beans, which start out at four or five percent, and then just go up from there. (Bengal gram is just another name for garbanzo beans, or chickpeas.)

If you mix cooked black beans with a nice fresh fecal sample, there’s so much fiber and resistant starch in those beans, the pH drops, as good bacteria churn out beneficial short-chain fatty acids, which are associated with lower colon cancer risk, as I’ve talked about—both indirectly  and directly. The more of this poopy black bean mixture you smear on human colon cancer, the fewer cancer cells survive.

Or, we can eat berries with our meals that act as starch blockers. Raspberries, for example, completely inhibit the enzyme that we use to digest starch, leaving more for our friendly flora. So, putting raspberry jam on one’s toast, strawberries on one’s cornflakes, or making blueberry pancakes may allow one’s good bacteria to share in some of the breakfast bounty.

Another way to feed our good bacteria is to eat intact grains, beans, nuts, and seeds. If you split people up into two groups, and have them eat the same food, but in one group, the seeds, grains, beans, and chickpeas they were eating were in more or less whole form, and in the other group, they were ground up, what happens? So, for example, for breakfast, the whole grain group got muesli for breakfast, and the ground grain group got the same muesli, but blended up into a porridge. Similarly in the whole group, beans were added to salads, whereas in the ground group, they were blended up into hummus. Note: both groups were eating whole grains, not refined.  Whole grains – they were eating whole foods. It was just that in the ground grain group, the whole grains, beans, and seeds were just made into flour or blended up.

So, what happened? The whole grain diet doubled their stool size, more than the ground grain diet—even though they were eating the same food, the same amount of food. Why? Because there was so much more for our bacteria to eat, they grew so well, they appeared to bulk up the stool. Even though people chewed their food, large amounts of apparently whole seeds were recovered from stools.

But, on closer inspection, they weren’t whole at all; our bacteria were having a smorgasbord. The little bits and pieces left behind after we chew them transport all this starch and goodies straight down to our good bacteria. And, as a result, stool pH dropped, as our bacteria were able to churn out so many of those short-chain fatty acids. And so, whole grains are great, but intact whole grains may be even better, allowing us to feed our good gut bacteria with the leftovers.

Once in our colon, starches have been found to have the same benefits as fiber: softening and bulking our stools, and reducing colon cancer risk by decreasing pH, increasing short-chain fatty acid production, reducing products of protein fermentation—also known as products of putrefaction—and decreasing secondary bile products.

So, hey, if resistant starch is so great, why not just take resistant starch pills? Commercial preparations of resistant starch are now available; this should be no surprise to anyone. Food scientists have developed a number of resistant starch-enriched products. After all, it’s “difficult to recommend a high-fiber diet to the general public.” Wouldn’t it be easier to just enrich some junk food? And indeed, now you can buy Pop-Tarts bragging that they contain resistant corn starch.

But just taking resistant starch supplements does not work. There have been two trials so far, trying to prevent cancer in people with genetic disorders, that put them at extremely high risk—as in virtually 100% chance of getting cancer—and resistant starch supplements didn’t help. Same here.

So, we’re either barking up the wrong tree, or the development of hereditary colon cancer is somehow different than regular colon cancer. Or, you can’t emulate the effects of naturally occurring dietary fiber in plant-rich diets by just giving people some resistant starch supplement.

For example, for resistant starch to work, it has to get all the way down to the end of the colon, where most tumors form. But, if the bacteria higher up eat it all, then it may not be protective. So, we may have to also eat fiber to push it along. Thus, we either eat huge amounts of resistant starch—up near the levels in Africa, twice as much as was tried in the two cancer trials—or consume foods rich in both resistant starch and fiber.

“In other words, from a public health perspective, eating more of a variety of whole plant food rich in dietary fibre, including whole grains, vegetables, fruits, and [beans], is a preferable strategy for reducing cancer risk.”

Please consider volunteering to help out on the site.

Image thanks to Young Sok Yun 윤영석 via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Resistant starch wasn’t discovered until 1982. Before that, we thought all starch could be digested by the digestive enzymes in our small intestine. Subsequent studies confirmed that there are indeed starches that resist digestion, and end up in our large intestine, where they can then feed our good bacteria—just like fiber does. Resistant starch is found naturally in many common foods, including grains, vegetables, beans, seeds, and some nuts—but in small quantities; just a few percent of the total. There are a few ways, though, to get some of the rest of the starch to join the resistance.

When regular starches are cooked and then cooled, some of the starch recrystallizes into resistant starch. For this reason, pasta salad can be healthier than hot pasta, and potato salad can be healthier than a baked potato. But the effect isn’t huge. The resistant starch goes from about three percent up to four percent. The best source of resistant starch is, therefore, not from eating cold starches, but from eating beans, which start out at four or five percent, and then just go up from there. (Bengal gram is just another name for garbanzo beans, or chickpeas.)

If you mix cooked black beans with a nice fresh fecal sample, there’s so much fiber and resistant starch in those beans, the pH drops, as good bacteria churn out beneficial short-chain fatty acids, which are associated with lower colon cancer risk, as I’ve talked about—both indirectly  and directly. The more of this poopy black bean mixture you smear on human colon cancer, the fewer cancer cells survive.

Or, we can eat berries with our meals that act as starch blockers. Raspberries, for example, completely inhibit the enzyme that we use to digest starch, leaving more for our friendly flora. So, putting raspberry jam on one’s toast, strawberries on one’s cornflakes, or making blueberry pancakes may allow one’s good bacteria to share in some of the breakfast bounty.

Another way to feed our good bacteria is to eat intact grains, beans, nuts, and seeds. If you split people up into two groups, and have them eat the same food, but in one group, the seeds, grains, beans, and chickpeas they were eating were in more or less whole form, and in the other group, they were ground up, what happens? So, for example, for breakfast, the whole grain group got muesli for breakfast, and the ground grain group got the same muesli, but blended up into a porridge. Similarly in the whole group, beans were added to salads, whereas in the ground group, they were blended up into hummus. Note: both groups were eating whole grains, not refined.  Whole grains – they were eating whole foods. It was just that in the ground grain group, the whole grains, beans, and seeds were just made into flour or blended up.

So, what happened? The whole grain diet doubled their stool size, more than the ground grain diet—even though they were eating the same food, the same amount of food. Why? Because there was so much more for our bacteria to eat, they grew so well, they appeared to bulk up the stool. Even though people chewed their food, large amounts of apparently whole seeds were recovered from stools.

But, on closer inspection, they weren’t whole at all; our bacteria were having a smorgasbord. The little bits and pieces left behind after we chew them transport all this starch and goodies straight down to our good bacteria. And, as a result, stool pH dropped, as our bacteria were able to churn out so many of those short-chain fatty acids. And so, whole grains are great, but intact whole grains may be even better, allowing us to feed our good gut bacteria with the leftovers.

Once in our colon, starches have been found to have the same benefits as fiber: softening and bulking our stools, and reducing colon cancer risk by decreasing pH, increasing short-chain fatty acid production, reducing products of protein fermentation—also known as products of putrefaction—and decreasing secondary bile products.

So, hey, if resistant starch is so great, why not just take resistant starch pills? Commercial preparations of resistant starch are now available; this should be no surprise to anyone. Food scientists have developed a number of resistant starch-enriched products. After all, it’s “difficult to recommend a high-fiber diet to the general public.” Wouldn’t it be easier to just enrich some junk food? And indeed, now you can buy Pop-Tarts bragging that they contain resistant corn starch.

But just taking resistant starch supplements does not work. There have been two trials so far, trying to prevent cancer in people with genetic disorders, that put them at extremely high risk—as in virtually 100% chance of getting cancer—and resistant starch supplements didn’t help. Same here.

So, we’re either barking up the wrong tree, or the development of hereditary colon cancer is somehow different than regular colon cancer. Or, you can’t emulate the effects of naturally occurring dietary fiber in plant-rich diets by just giving people some resistant starch supplement.

For example, for resistant starch to work, it has to get all the way down to the end of the colon, where most tumors form. But, if the bacteria higher up eat it all, then it may not be protective. So, we may have to also eat fiber to push it along. Thus, we either eat huge amounts of resistant starch—up near the levels in Africa, twice as much as was tried in the two cancer trials—or consume foods rich in both resistant starch and fiber.

“In other words, from a public health perspective, eating more of a variety of whole plant food rich in dietary fibre, including whole grains, vegetables, fruits, and [beans], is a preferable strategy for reducing cancer risk.”

Please consider volunteering to help out on the site.

Image thanks to Young Sok Yun 윤영석 via flickr

Doctor's Note

What’s so great about resistant starch? See my video Resistant Starch and Colon Cancer.

I first broached the subject of intact grains in my video Are Green Smoothies Bad for You?.

Why should we care about what our gut flora eats? See Gut Dysbiosis: Starving Our Microbial Self.

Did I say putrefaction? See Putrefying Protein and “Toxifying” Enzymes.

Berries don’t just help block starch digestion, but sugar digestion as well. See If Fructose Is Bad, What About Fruit?.

The whole attitude that we can just stuff the effects into a pill is a perfect example of reductionism at work. See Reductionism and the Deficiency Mentality and Why is Nutrition So Commercialized? for more on this.

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