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Here's how to make your carbs healthier - Wisdom Wednesdays · Hardiness with Dr Paul Taylor

• 0:05
  Speaker 1: Hey everybody, welcome to another edition of Wisdom Wednesdays.
• 0:08
  Speaker 2: Now, if you listened to last week's Wisdom Wednesday, you'll
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  Speaker 2: know I talked about how if we didn't feed our
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  Speaker 2: microbes in our gut, we could turn them into cannibals
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  Speaker 2: and they could eat our mucous membrane. So this week,
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  Speaker 2: I want to follow that up with a way that
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  Speaker 2: you can not only feed those critical microbes that will
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  Speaker 2: give you the short chain fatty acids in return, but
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  Speaker 2: but also make your carbohydrates.
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  Speaker 1: A shitload more healthy.
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  Speaker 2: And the key is actually changing the physical structure of
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  Speaker 2: the starch or some of the starch that's in the carbohydrate.
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  Speaker 2: And that change that we do appears to have meaningful
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  Speaker 2: effects on both blood glucose and gut health. And this
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  Speaker 2: is about increasing the amount of resistant starch. Now, most
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  Speaker 2: starch in foods such as rice, potatoes, and pasta... is
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  Speaker 2: normally broken down in the small intestine into glucose. So
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  Speaker 2: when you cook these foods in water, the starch granules
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  Speaker 2: swell up and their.
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  Speaker 1: Structure becomes much more open.
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  Speaker 2: And this process is called gelatinization, and it makes the
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  Speaker 2: starch highly accessible to our digestive enzymes and makes them
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  Speaker 2: be able to obviously digest them easier. So in simple terms,
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  Speaker 2: freshly cooked starch is relatively easy to, for your digestive
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  Speaker 2: system to get at. You have enzymes called amylase enzymes.
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  Speaker 1: They attack it.
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  Speaker 2: The glucose is released and it's absorbed through our intestine
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  Speaker 2: and the blood glucose rises. But there's a real cool
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  Speaker 2: trick that you can do. When you cook that starch
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  Speaker 2: and then you cool it afterwards, something pretty interesting happens.
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  Speaker 2: some of the starch molecules, particularly the amylose, begin to
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  Speaker 2: reorganize themselves into these tighter, more crystalline structures, more complex structures.
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  Speaker 2: And the technical term for this is retrogradation. And that
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  Speaker 2: retrograded starch is much, much harder for our digestive enzymes
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  Speaker 2: to break down. And then it becomes what's known as
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  Speaker 2: type 3 resistant starch or RS3. Now, instead of all
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  Speaker 2: of that starch being digested and absorbed in the small intestine,
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  Speaker 2: some of it, because it's resistant, continues down into the
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  Speaker 2: large intestine.
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  Speaker 1: And that's where the story becomes really interesting.
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  Speaker 2: So let's talk about a pretty famous study, a rice experiment.
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  Speaker 2: And this was a 2015 paper in the Asia.
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  Speaker 1: Pacific Journal of Clinical Nutrition.
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  Speaker 2: And I actually went back to the original paper because
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  Speaker 2: the experiment is actually worth looking at in some detail.
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  Speaker 2: So what the researchers did is they compared freshly cooked
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  Speaker 2: white rice with rice that had been cooked and then
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  Speaker 2: either cooled for 10 hours at room temperature or refrigerated
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  Speaker 2: for 24 hours at four degrees and then reheated afterwards. Now,
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  Speaker 2: the freshly cooked rice contained about 0.64 grams of resistant
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  Speaker 2: starch per 100 grams, so not very much. Cooling it
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  Speaker 2: increased that to 1.3 grams, so pretty much doubled the
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  Speaker 2: resistant starch, while refrigerating it for 24 hours and then
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  Speaker 2: even reheating it increased the resistant starch to 1.65 grams
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  Speaker 2: per 100 grams, so almost a tripling. So the refrigerated
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  Speaker 2: and then reheated rice contained almost, well, two and a
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  Speaker 2: half to three times as much resistant starch as the
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  Speaker 2: freshly cooked rice. They then did a small randomized crossover
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  Speaker 2: experiment in healthy adults. So they had 14 participants, so
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  Speaker 2: it's a small study, but they were included in the
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  Speaker 2: final glucose analysis. And each person had a meal containing
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  Speaker 2: either the freshly cooked rice or the cooked, refrigerated, and
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  Speaker 2: reheated rice. And the 2R glucose response, and this is
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  Speaker 2: measured as what's called the area under the curve, was
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  Speaker 2: about 18% lower with the cooled and reheated rice. So
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  Speaker 2: it was 125 versus 152 millimoles per minute per liter. Now,
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  Speaker 2: 14 people obviously isn't a massive study. And the difference
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  Speaker 2: just reached statistical significance here. But it did provide a
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  Speaker 2: nice demonstration of the underlying physiology. If you change the
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  Speaker 2: starch structure, you can change the metabolic response in our
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  Speaker 2: bodies to the same basic food. And it isn't just rice.
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  Speaker 2: So similar things have been demonstrated with potatoes and pasta.
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  Speaker 2: So a 2018 Food Research International study found that cooling
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  Speaker 2: cooked potatoes for 24 hours increased resistance starts substantially compared.
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  Speaker 1: With only allowing them to cool briefly.
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  Speaker 2: So the precise amount vary depending on the particular version
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  Speaker 2: of the potato. For those who aren't Irish, there's a
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  Speaker 2: shitload of different types of potato out there.
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  Speaker 1: And that's an important.
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  Speaker 2: Reminder that we're dealing with food rather than pharmaceuticals, right?
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  Speaker 2: And there was a particularly interesting randomized crossover pasta study
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  Speaker 2: published in the journal Foods. Participants ate identical pasta meals,
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  Speaker 2: freshly cooked, and some then ate cold, or some ate
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  Speaker 2: cooled and then reheated. And the reheated pasta produced a
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  Speaker 2: significantly smaller overall glucose response than the freshly cooked pasta,
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  Speaker 2: and the blood glucose returned towards baseline much more quickly.
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  Speaker 1: So a much better metabolic effect.
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  Speaker 2: In fact, a more recent 2026 trial in 32 adults
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  Speaker 2: with type 1 diabetes found a really striking difference. They
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  Speaker 2: found that pasta cooled for 24 hours and then reheated
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  Speaker 2: contained substantially more resistant starch and produced a lower glucose
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  Speaker 2: peak and a much smaller post-meal glucose rise than freshly
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  Speaker 2: cooked pasta. Now, that doesn't mean that people with diabetes
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  Speaker 2: should start changing insulin doses on the basis of this, obviously,
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  Speaker 2: but it does give us more evidence that this effect
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  Speaker 2: is physiologically real. But the glucose may only be part
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  Speaker 2: of the story. As I said earlier, resistant starch is really,
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  Speaker 2: really important, particularly when it reaches the colon, and we
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  Speaker 2: touched on this last week. Because we haven't digested it,
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  Speaker 2: our gut microbes, they get the first crack at it
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  Speaker 2: in the colon. So certain bacteria ferment these resistant starches
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  Speaker 2: and they produce the short chain fatty acids that I
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  Speaker 2: talked about last week, particularly butyrate, acetate and propionate. Now,
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  Speaker 2: you may have heard me talk about these before, particularly butyrate.
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  Speaker 2: It is one of the main fuels used by the
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  Speaker 2: cells lining your colon. So basically you stop those cannibals
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  Speaker 2: that I talked about last week. But butyrate also plays
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  Speaker 2: important roles. in maintaining the intestinal barrier and also in
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  Speaker 2: regulating inflammatory and metabolic signaling. And we know that short
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  Speaker 2: chain fatty acids are actually good for your heart and
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  Speaker 2: good for your brain. So resistant starch has this interesting
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  Speaker 2: double effect. You digest it less rapidly in the small
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  Speaker 2: intestine and then you deliver more fermentable substrate to the
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  Speaker 2: microbes in the large intestine and you actually reduce the
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  Speaker 2: calories as well. Now, this isn't just theoretical. There was
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  Speaker 2: a systematic review and meta-analysis of randomized controlled trials in
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  Speaker 2: healthy adults. And it found that resistant starch supplementation significantly
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  Speaker 2: increased the butyrate in their feces.
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  Speaker 1: And it also lowered the pH of the colon significantly.
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  Speaker 2: And both of those are consistent with increased fermentation in
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  Speaker 2: your colon or your large bowel. And a more recent
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  Speaker 2: meta-analysis looked specifically at the microbiome, found that resistant starch
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  Speaker 2: intake changed several bacterial populations, increasing a variety of almost
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  Speaker 2: unpronounceable Bacteria such as Fecalibacterium, Bifidobacterium, Agathobacter, and Ruminoccus. And importantly,
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  Speaker 2: the response varied enormously between people and according to the
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  Speaker 2: type of resistance starts being consumed, right?
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  Speaker 1: So we are... Very, very different. Not everybody has the
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  Speaker 1: same response.
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  Speaker 2: But the big message here is that resistant starch actually
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  Speaker 2: is very good for your ecosystem or your microbial ecosystem,
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  Speaker 2: particularly in your colon. Some people benefit more than others.
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  Speaker 2: The question is here, really, is resistant starch actually fiber?
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  Speaker 2: And functionally, yes, it is fiber. It escapes digestion in
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  Speaker 2: the small intestine, as I said earlier. And it behaves
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  Speaker 2: more like fermentable dietary fiber than conventional starch, which is
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  Speaker 2: why resistant starches are commonly included in the broader category
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  Speaker 2: of dietary fiber. But there's a little tweak that I
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  Speaker 2: would make to some of the claims that you would
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  Speaker 2: see online, that things like cooling turns carbohydrate into fiber.
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  Speaker 2: It's catchy, but it's a little bit too simplistic. You're
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  Speaker 2: not converting all of the carbohydrate into fiber. you're converting
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  Speaker 2: a relatively small proportion of the digestible starch into that resistant.
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  Speaker 1: Starch, right?
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  Speaker 2: So as I said earlier in the rice study, the
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  Speaker 2: resistance starch rose from 0.64 to 1.65 grams per 100
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  Speaker 2: grams of cooked rice, right? So even though it's a
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  Speaker 2: two and a half times increase, you don't get a
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  Speaker 2: shitload of it, right? But it is actually beneficial for
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  Speaker 2: our gut microbiome as it was shown in those other studies.
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  Speaker 2: And a systematic review and meta-analysis of 19 randomized control
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  Speaker 2: trials found that resistant starch interventions produced modest improvements in
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  Speaker 2: fasting glucose and insulin resistance. The effects tended to be
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  Speaker 2: more pronounced in studies using larger amounts of resistant starch.
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  Speaker 2: and interventions that lasted longer than eight weeks. And that
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  Speaker 2: kind of makes.
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  Speaker 1: Sense, right? But taken together, all of this.
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  Speaker 2: Evidence points in the same general direction. Slowing starch digestion
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  Speaker 2: and increasing the amount reaching the colon has useful metabolic
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  Speaker 2: effects in terms of improving those short chain fatty acids
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  Speaker 2: we talked about, but also protecting your mucous membrane because
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  Speaker 2: you're feeding these microbes that if you don't give them
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  Speaker 2: that food, they start to eat your mucous membrane. They
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  Speaker 2: turn into cannibals, which I talked about extensively last week.
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  Speaker 2: So from a practical perspective, if you do have rice, potatoes,
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  Speaker 2: pasta in your diet, cooking them and then cooling them
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  Speaker 2: and then even cooking them afterwards makes them a better
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  Speaker 2: food with more of that resistant starch, slightly less calories,
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  Speaker 2: but the bigger impact is on your gut microbiome. Now,
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  Speaker 2: if you cool them and don't reheat them, there'll be
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  Speaker 2: even more resistant starches, but You've got to like cold pasta,
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  Speaker 2: cold rice.
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  Speaker 1: And cold potatoes to be able to do that right.
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  Speaker 2: But this is where pasta salads and potato salads are
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  Speaker 2: actually quite useful and they're healthier than the ones that
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  Speaker 2: are just freshly cooked. Right. This isn't the only way
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  Speaker 2: that you can get resistant starch into your diet.
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  Speaker 1: Legumes and firm bananas.
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  Speaker 2: Are particularly high in resistant starch, as is banana flour
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  Speaker 2: and potato starch is super, super high in resistant starch.
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  Speaker 2: And legumes in particular have quite a lot of resistant
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  Speaker 2: starch alongside conventional fiber starch. But the other thing I
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  Speaker 2: think for your carbohydrates is to don't eat them on
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  Speaker 2: their own. We know that having your carbohydrates with either
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  Speaker 2: fat or protein actually slows this and reduces the total
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  Speaker 2: spike that you get in glucose. and actually slows the
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  Speaker 2: rise in glucose, which is much better for you. So
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  Speaker 2: combining your pasta with protein, vegetables, and fat is.
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  Speaker 1: A good way to do it.
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  Speaker 2: But also cooking and cooling and then reheating will also
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  Speaker 2: add a little bit of extra into it.
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  Speaker 1: Now, next week, I want to talk about a.
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  Speaker 2: Little nuance behind all of this. So I've talked for
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  Speaker 2: the last two weeks about the benefits of fiber. But
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  Speaker 2: it turns out a pretty cool study from Stanford shows
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  Speaker 2: that not everybody benefits the same. And there is another
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  Speaker 2: type of food that is even better for your gut
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  Speaker 2: microbiome than fiber or resistant starch.
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  Speaker 1: If you tune in next week, we'll talk about that.
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  Speaker 1: Catch you next time.