Dear Friends,
A lot of people understand that fiber is important, which is good. But what many often don’t realize is that not all fiber is the same.
And there is one type of fiber that may be especially important for the gut microbiome — yet modern diets provide very little of it.
That fiber is called resistant starch.
And in my view, resistant starch may be one of the most overlooked nutrients missing from diets in the 21st century.
So today, I want to review why resistant starch matters, why modern diets often fall short, and why a low-dose resistant starch fiber like Solnul, a brand we prefer for supplements, may be such a smart way to help fill the gap.
Let’s start with the bigger idea.
For most of human history, people regularly ate starchy plants that naturally contained resistant starch.
This provided fermentable fuel that helped shape the gut microbiome over time.
But modern food processing, refinement, cooking practices and dietary preferences have steadily removed much of that resistant starch from the diet.
In other words, modern food systems changed faster than human biology — and an important nutrient got left behind.
That is a powerful idea. Because when we talk about the microbiome, we often focus on probiotics — the bacteria themselves. But the bacteria also need to be fed.
And resistant starch appears to be one of the microbiome’s favorite foods. Unfortunately, resistant starch is a kind of a “lost nutrient” in our diets.
Current intake is estimated at only about 4 grams per day in the United States and Europe, while 15 to 20 grams per day is often cited for supporting bowel, gut, and metabolic health.
That means most of us are nowhere close.
What Exactly is Resistant Starch?
It is a starch that resists digestion in the small intestine and reaches the large intestine, where it can be fermented by beneficial gut microbes.
That is what makes it different from ordinary starch, which is easily broken down by digestive enzymes into glucose that enters the bloodstream.
Here’s what makes it different from many other fibers. It reaches the large intestine intact like insoluble fiber but is also fully fermentable like soluble fiber.
So resistant starch gives you a best-of-both-worlds effect, essentially behaving like both major types of fiber.
That is why resistant starch is getting more attention, especially as a supplement. It is not just about how much fiber you consume. It is also about what type of fiber you are consuming.
And that brings us to Solnul.
Solnul is a potato-derived resistant starch — specifically a resistant starch type 2, or RS2 — that is upcycled from the potato processing industry in Canada.
Potatoes are nature’s richest source of resistant starch and Solnul preserves that native resistant starch without chemical modification.
But what really makes Solnul interesting is not just where it comes from. It's about the health support it can deliver at a relatively small dose.
For years, resistant starch research often focused on very large amounts — 30 grams or more — which are not very realistic for most people in diet or supplement products.
But Solnul was introduced as a low-dose resistant starch, with benefits demonstrated at just 3.5 grams.
That matters a lot because a fiber ingredient only helps if people can actually use it consistently.
How if Helps the Gut Microbiome
Now let’s get to the heart of the story: the microbiome.
Research with Solnul shows that this resistant starch selectively feeds beneficial bacteria and significantly increases two microbes that are getting a lot of attention right now: Bifidobacterium and Akkermansia.
Many people have heard of Bifidobacterium because it has long been associated with digestive health.
But Akkermansia is the one getting a lot of interest lately, especially for metabolic health and healthy blood sugar metabolism.
And that’s not all it does. Akkermansia also plays a meaningful role in the health of the gut lining and gut barrier function.
That is important because the gut barrier plays a huge role in overall health. It acts like a protective lining — helping keep harmful substances out while allowing nutrients in.
So when you support microbes that are associated with a healthier gut barrier, you are doing more than just “feeding the microbiome.”
You may also be helping the body maintain one of its most important protective systems.
More evidence for Solnul’s support of intestinal barrier function comes from a study showing that taking 3.5 grams of Solnul can help reduce levels of histamine and histamine secreting gut bacteria.
This is important for maintaining a healthy inflammation response in the gut, and it’s also a signal of better intestinal barrier function.
And it helps explain why the benefits of resistant starch may go beyond simple digestion. But let’s stay with digestive health for a moment, because there is a very practical payoff here too.
Supporting Stool Quality
Many fibers can help support regularity and frequency. But one interesting finding with Solnul is that it appears to help promote consistent stool quality.
This was true in people experiencing loose stools and in those with stools classified as too hard, making it a struggle to go regularly and comfortably.
Solnul appears to help both groups improve stool quality, indicating better bowel and gut function.
That is the kind of real-world result people care about. Not just changing bacteria on paper. But helping the digestive system work better and more consistently.
Now, one thing I really like about the Solnul science story is that it tries to look beyond just which microbes went up or down.
Solnul takes more of a whole-system approach by also looking at metabolic changes — not just microbiome composition.
That is a useful distinction, because it suggests we should not only ask, “Which good bacteria increased?” but also, “What is the microbiome actually doing differently?”
And this is where the story starts to broaden. If the microbiome is healthier, and if the gut barrier is stronger, that can influence a lot of downstream functions.
One is nutrient absorption. By strengthening the gut lining, Solnul supported absorption of vitamin A, vitamin E, and choline in research.
This is a fascinating idea, because it suggests that improving the gut environment may help the body do a better job using the nutrients you are already consuming.
Another area is the gut-skin axis.
Healthy-looking skin is closely connected to the gut through the microbiome and Solnul has found that supplementation may help reduce blood markers associated with collagen breakdown, including hydroxylysine and hydroxyproline.
As you may know, maintaining healthy collagen is not only important for skin appearance, but joints and muscles too.
And then there is metabolic health.
Studies with Solnul found that this resistant starch may help support metabolic function by increasing Akkermansia, supporting the gut barrier, and reducing serum free fatty acids, which many researchers believe is one of the earliest markers of metabolic dysfunction.
Although the gut microbiome and digestive health is what first comes to mind when we think of fiber, I do think it is important to mention these broader connections, because they help explain why resistant starch may matter so much.
Not Just a “Fiber for Fiber’s Sake” Story.
This is a microbiome support story, a gut barrier story, and potentially a much broader wellness story too.
And that brings us back to the main point.
Resistant starch may be one of the missing fibers in the modern diet. The microbiome appears to do very well when it has access to it. But most of us are not getting much of it.
That is why I think Solnul is so interesting.
It helps fill that resistant starch gap in a way that is: practical, low-dose, well tolerated, and supported by meaningful microbiome and gut barrier research.
So to summarize:
Resistant starch is a unique fermentable fiber that reaches the large intestine and feeds beneficial microbes.
Modern diets provide far less of it than they once did.
Solnul is a potato-based resistant starch that helps fill that gap at a practical 3.5 gram dose.
It supports beneficial bacteria like Bifidobacterium and Akkermansia, helps support the gut barrier, and may help improve digestive balance, nutrient absorption, and broader metabolic function.
That is why resistant starch is getting new attention. And why I think it deserves a fresh look from anyone interested in gut and microbiome health.
If you want to know where to find it, we made Solnul one of the featured ingredients in our TrueDYB digestive formula.
Yours for Good Health,
Carl Pradelli
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