Within our body are small structures called “Toll-like Receptors (TLRs).” These receptors are an important part of our immune system. TLRs are used by components of our immune system to detect the presence of microbes, ie. fungal and bacterial pathogens, that do not belong inside of us, and need to be eliminated. This is a key feature of our “innate immune system.” The innate immune system is our first-line defense against microbial infections. Prolonged over-stimulation of our innate immune system leads to chronic inflammation and a steady decline in health, often resulting in autoimmune diseases such as diabetes, arthritis, Crohn’s disease, etc… The list is long. The TLRs found in our gut have been shown to interact with resistant starch, as found in potatoes. The interaction reduces inflammation and strengthens the immune system as well as guiding the development of serotonin, an important brain chemical.
RS2 as an Immunity Booster
Resistant Starch (RS) is a key-player in the maintenance and upkeep of TLRs. In just the last couple years, researchers from around the world have been examining just how closely related TLRs and our intake of RS actually are.
The 2015 paper, “Resistant starches differentially stimulate Toll-like receptors and attenuate proinflammatory cytokines in dendritic cells by modulation of intestinal epithelial cells,” examined exactly how RS interacts with the immune system. This paper opened an entire new line of thinking in how researchers view RS, as stated in the paper:
Immune effects of dietary fibers are often attributed to microbiota-dependent effects. However, some dietary fibers have been reported to bind to specific receptors on immune cells, suggesting microbiota-independent, immune-modulatory effects.
For decades, researchers thought that “fiber” acted by feeding beneficial bacteria (probiotics) who did all the work. Now, for the first time, we see that certain fiber…resistant starch…due to its size and shape, directly binds with TLRs and has an immediate effect on our innate immune system!
The fiber used in this study was high amylose corn starch, a type 2 resistant starch (RS2), sold as a cooking ingredient called Hi-Maize. This same type of RS2 is also found in raw potato starch and banana flour. Also used in the study was Novelose 330, a cooked and cooled (RS3) product not available for consumer purchase, but easily made at home by cooking and cooling your beans, rice, potatoes, and corn meal.
This study clearly shows that RS works much of its magic by simply being there. A spoonful or two of the raw powders, or a serving or two of leftovers every day.
Up to now it was assumed that resistant starch mainly contributes to anti-inflammatory effects by enhancing production of short chain fatty acids by the microbiota. Here, we show that resistant starch by direct interaction with [the innate immune system] can induce a regulatory immune phenotype independent of effects on microbiota. This effect is to our opinion profound…(emphasis mine).
And a second study…
Of further note, another 2015 paper, “Responses in Colonic Microbial Community and Gene Expression of Pigs to a Long-term High Resistant Starch Diet,” Studied the effects of the innate immune system in pigs fed raw potato starch long-term.
Intake of raw potato starch (RPS) has been associated with various intestinal health benefits, but knowledge of its mechanism in a long-term is limited.
Much to the researchers surprise, they discovered that the real “magic” in raw potato starch (RPS) is not the effects on bacteria, butyrate, and all of the other attributes of fiber, but the effect of RPS on the innate immune system!
We found that compared with the control diet, the RPS diet changed the colonic expression profile of the host gene involved in immune response pathway…
We can assume, then, that much of the beneficial change we see to the gut flora is due, in part, to the effects of resistant starch on our immune system.
Toll-like Receptors and Brain Function
Toll-like Receptors have been in the news recently.
Two papers from 2016 suggest that TLRs are responsible not only for keeping our innate immune system running smoothly, but also in directing the flow of chemicals produced by gut bugs and destined for the brain.
It is clear that microbiota could play a key role in intestinal homeostasis, not only through activation of TLRs but also as a producer of metabolites as butyrate or serotonin.
If you are brave, read the paper. It describes how TLR-2 can control the byproducts produced by gut bacteria and ensure they are turned into serotonin. Serotonin is an important brain chemical, involved in processes like breathing, body temperature, and appetite. In the gut, serotonin reduces inflammation and controls gut motility. It’s quite a lot to grasp, but rest assured that the resistant starch found in potato diets contributes immensely to the success of these diets.
Gut microbes metabolize dietary fiber and resistant starch to produce a wide variety of metabolites, including short-chain fatty acids (SCFAs), which are used as nutrients by colonic epithelial cells and influence host physiology. Recent studies have uncovered a role of SCFAs in the production of serotonin (5-hydroxytryptamine [5-HT]) by enterochromaffin cells (ECs) of the intestinal epithelium. ECs are the largest source of serotonin in the body, which, among other functions, regulate GI motility and platelet function.
OK, OK…this second paper is even harder to read than the first, so again, if you are brave and have a deep understanding of the immune system, click and read. Otherwise, I’ll end with a nice drawing from the paper to illustrate how incredibly complex this all really is. But feel free to read and make your own conclusions! Potatoes contain ample amounts of both fiber and resistant starch, making potatoes the perfect food for immune-boosting, weight loss diets.
Toll-like Receptors are an important part of our overall health, TLR genes are influenced directly by the consumption of resistant starch, both uncooked and cooked. My book, The Potato Hack describes an all-potato diet that leads to weight loss. Possibly the best feature of a potato diet is not the weight loss, but the effects on our immune system which will lead to long term health benefits. Can The Potato Hack be used to prevent, or even cure, autoimmune diseases? Already the FDA has approved statements that Hi-Maize can help to prevent diabetes, a well-known autoimmune condition.
I’m far from an expert in immunology, people spend entire careers studying this field. I hope my attempts to explain the topic were adequate.
In parting, I’d like to point out that, despite my earlier attempts to compare Toll-like Receptors with toll-booths on highways, the name actually came from German speaking researchers, who, upon discovering TLRs, proclaimed, “Das ist ja toll!”
And it is cool, isn’t it, how everything is connected?
Eat your spuds.