In Traditional Chinese Medicine, one of the primary uses of Qing Pi and Chen Pi is to maintain a healthy digestive system. In recent years, Western Science has helped uncover some of the things citrus peel might be doing to trigger these positive effects.
Even if you don’t have something obvious like acid reflux or chronic constipation, I’d still encourage you to take a moment to read this short article. Suboptimal digestion doesn’t always manifest itself with severe symptoms, but it can still get in the way of your mood, energy, recovery, immunity and weight management.
Let me explain why.
What’s Your Second Brain Telling You?
Gastroenterologists are discovering just how intelligent and how deeply involved with your health your gut actually is. Far from being a dumb plumbing system, there’s nearly as much neurological mass in your gut as there is in your entire brain. Some leading gastroenterologists now refer to the gut as a “second brain.”
While your “first brain” is a massive source of top-down intelligence, carefully organizing and regulating activity, your “second brain” is a massive source of bottom-up intelligence, collecting and responding to output from trillions of microscopic life forms.
A Massive, Bottom-Up Intelligence
There are more bacteria in your gut than there are cells in your body. (Makes sense to treat them with a little respect, doesn’t it?) Because bacteria have such a short life, they adapt and evolve much more quickly than you can. The chemical information they put out informs the rest of your body about where you are, what’s available, what’s missing, what you’re up against, and what dangers are lurking.
You can think about them almost like sense organs out there taking tiny samples of your environment. For most of human existence, our food came directly from our physical environment and told the low level intelligence agents in our gut a lot about our surroundings and our situation. (Your ability to grab processed food from the pantry is, as you know, a modern luxury.)
What’s “You” and What’s “Not You?”
Most people think of their digestive tract as being on the inside, but from your body’s perspective, what’s inside your digestive tract is actually still on the outside. Weird, isn’t it? Things aren’t technically “in” you until they’re permitted to pass through the digestive wall and into your bloodstream. From top to bottom, your digestive tract is carefully shielded, just like your skin, to prevent alien chemical and biological agents from getting through.
If you were designing the defense of a castle, where would you put the most of the guards? On the wall, right? Your body does the same thing. They’re discovering that the vast majority of the intelligence of your immune system lives in your gut, just like you’d expect of good guards. And that’s why the health of your gut flora, and what it’s made of, directly impacts the health of the rest of your body.
For example, if your gut develops a Candida overgrowth (very common these days because of excessive use of antibiotics and excessive carbohydrate intake) it weakens and stretches your intestinal wall and penetrates into your bloodstream. There, it unleashes toxic byproducts that can harm other organs and sends your immune system into a state of alarm.
A Breach in the Wall
Further, once the gut lining is compromised, all sorts of other things start getting through, leading to near-constant immune reactions and widespread inflammatory responses. It’s not so different from blowing a hole in the castle wall. You can have immune reactions to perfectly healthy foods if partially digested chunks of them get through the wall. It’s hard to stay healthy if you start having bad reactions to good things.
How Citrus Peel May Help Maintain Your Gut Health
Protection for a Damaged Gut
Two of the agents in citrus peel, Limonene and Alpha-Pinene, exist to help protect oranges and tangerines from being devoured by pathogens. So it makes sense that citrus peel has been shown to have antibacterial and anti-fungal properties that may help protect your gut from an overgrowth of opportunistic pathogens. Alpha-pinene in particular is highly toxic to Candida albicans. In one study it killed 100% of it within 60 minutes.
In one study, Limonene demonstrated support for a healthy gut lining. Compared to controls, limonene induced new blood vessel formation around the injured area by activating a key rejuvenating compound called VEGF (vascular endothelial growth factor,). It also enhanced the production of mucous to protect the GI tract lining from further injury. By the end of the study, researchers observed that the cells in the digestive tissue were “better organized and more structurally sound”.
Citrus Peel May Modulate Gut Mobility For Sluggish or Overactive Digestion
The injection of citrus peel extract has been shown to support digestion by modulating the contraction of smooth muscle in the gut. Interestingly, Qing Pi has relieved cramps by inhibiting overactive contractions, and Chen Pi has increased the motility of a sluggish gut by encouraging the contraction of underactive muscles. Both seem to push back towards the balanced center.
What about things like heartburn, acid reflux, ulcers, and gallstones?
Alpha-Pinene has inhibited stomach ulcers by reducing the volume and acidity of gastric juice and by increasing gastric wall mucus,  while nobiletin has helped maintain the integrity of the mucus wall barrier. 
What’s more, most ulcers are initiated by an infection of a bacteria called helicobacter pylori, which has figured out a way to survive in the stomach by hiding near the glands that produce the acid and causing them to produce too much. One study found that an ethanol extract of citrus peel inhibited five clinical strains of H. pylori. 
The Limonene in citrus peel has shown some exciting potential for calming heartburn and acid reflux (GERD), and for acting as a widespread anti-inflammatory agent for the entire gut. ,
Finally, a preparation of Chen Pi has demonstrated effectiveness in dissolving gallstones in 134 patients.
Not too shabby! The thousands of years of exploration and refinement in Chinese medicine really are a goldmine of accumulated wisdom.
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