From the practitioner letters
What San Ren Tang does for a gut that swings between loose and stuck, and why Dr. Lan thinks it works.
Will Sheppy, L.Ac. · Guest contributor · September 2026
You know the gut I mean. Loose one week, backed up the next, bloated after most meals, and tired on top of it. The bloodwork is normal. The scope, if you had one, was normal. Somebody tells you nothing is wrong, and you go home still bloated.
Dr. Xuelan Qiu, who goes by Dr. Lan, is the pharmacist behind the Botanical Biohacking formulas we carry on Chorus and use in my clinic in Albany, Oregon. She writes to practitioners most weeks. Her latest letter was about the benefits of San Ren Tang, the old Three-Seed Decoction, and the version of it Botanical Biohacking makes called Peak Tea. I liked this one because she walked through how she thinks it works, step by step, and then admitted the finished tea has never been tested that way. You don't see that often.
The short version
San Ren Tang is a classical Chinese formula for damp heat: that heavy, bloated feeling you can't shake. Peak Tea is San Ren Tang plus two more herbs, bupleurum (Chai Hu) and virgate wormwood (Yin Chen Hao). Dr. Lan's idea is that it supports a calmer gut lining through butyrate, which your gut bacteria make, and helps the colon get its water balance back, whether you run loose or stuck. The science behind each step is published. The tea itself hasn't been tested in people. Use it as a short course, and check your medications first.
What Dr. Lan wrote about
Dr. Xuelan Qiu (“Dr. Lan”), Botanical Biohacking
Her patient isn't a diagnosis. It's a set of complaints: bloating, bowels that won't stay regular, and a low-grade inflammation in the gut that doesn't show up on any test but still colors the whole day. Fatigue sits underneath all of it. She's clear that this isn't a disease. It's the ground the digestion stands on, and the gut has lost its hold on it.
“The net effect is a return to normal fluid regulation rather than a push in either direction.”
Dr. Lan, Botanical Biohacking practitioner letter, September 2026
That's the part I want people to get. Most things you buy for your gut push one way. A laxative moves you, a binder stops you. If your gut swings both ways, pushing in one direction just sends you over to the other side. Her point is that Peak isn't pushing. It's helping the gut get back to running itself.
The pattern: damp heat in the middle
In Chinese medicine we call this damp heat, and it's easier to feel than to explain. Damp is heavy and sticky, like fluid that isn't moving. Heat is what builds up when that fluid sits too long. Put them together and you feel waterlogged and warm at the same time. I wrote more about the damp pattern San Ren Tang was built for on the clinic blog.
Signs this might be you
- Heaviness. Heavy head, heavy arms and legs, a body that feels thick.
- A full belly. Bloated after normal-sized meals. Appetite comes and goes.
- Bowels that can't make up their mind. Loose or sticky one week, sluggish the next.
- A sticky mouth, not much thirst. This is the classic clue. You run warm but you don't really want to drink.
- An afternoon slump. Energy drops after lunch. Some people feel warm in the afternoons.
When to see a doctor first
Blood in the stool, black stools, weight loss you can't explain, getting up at night to use the bathroom, a fever that won't go away, bad belly pain, or a new change in your bowels after fifty. Get those checked out first. Herbs can come later, alongside your medical care.
The formula: San Ren Tang, the Three-Seed Decoction
San Ren Tang comes from Wu Jutong's Wen Bing Tiao Bian (Systematic Differentiation of Warm Diseases). He finished it by 1798, and it was first printed in 1813. What he figured out is that this pattern punishes the obvious fixes. Make the person sweat and they get foggy. Purge them and they lose their energy. Give them moistening herbs and the damp just sinks in deeper. So the formula doesn't attack anything. It opens up all three levels of the body at once and lets the damp drain out.
- Xing Ren (apricot kernel). Opens up the top, the chest and lungs.
- Bai Dou Kou (white cardamom). Wakes up digestion in the middle and clears damp.
- Yi Yi Ren (coix seed). Drains damp down and out. A little cooling.
- Hou Po (magnolia bark) and Fa Ban Xia (prepared pinellia). Get stuck digestion moving and dry things out.
- Hua Shi (talc), Tong Cao (rice-paper pith) and Dan Zhu Ye (bamboo leaf). Clear heat out through the urine.
- Chai Hu (bupleurum) and Yin Chen Hao (virgate wormwood). The two herbs Botanical Biohacking added. They push the heat-clearing further and bring in the liver and gallbladder. That's ten herbs total.
Peak has a sibling. Wind Tea has the same San Ren Tang herbs built into Minor Bupleurum, plus real ginseng for people who are more run down. If you run hot and full, think Peak. If you're more worn out, think Wind. I compared the two in the Wind Tea post on the clinic blog.
“The finished blend has not itself been trialed against these endpoints.”
Dr. Lan
What I see in clinic
[WILL: clinic photo for a gut post. The usual neck-evaluation shot doesn't fit. Send one, or delete this line.]
The person I think of when I read this letter is the one whose bowels swing back and forth between loose and sluggish, who's bloated after meals, and whose tests keep coming back normal.
Dr. Lan says Peak helps both the loose side and the sluggish side, and I agree. I see it help both. The science she lays out explains the loose side better than the sluggish side (I'll get to that below), but in the clinic it works on both.
What I tell people to expect: your bowels change first. Stools get more formed, or easier to pass, depending on which way you were off. The energy comes back after that, not before.
[WILL: optional. What you pair Peak with for this pattern: points, Evil Bone Water, the foot soak, or nothing. Delete if you'd rather leave it out.]
What I'd add: don't fight heat with cold food
Fiber is good, but cold, raw, leafy greens can be too hard on this kind of gut and actually slow it down. The way we clear heat is by gently getting things moving, so the body isn't holding on to stool long enough for it to build heat and dryness. Warm, cooked food helps with that.
Beans are a really good choice. They have a good mix of soluble and insoluble fiber. Cooked plant foods like squash, and grains like quinoa, help too. Cucumbers are good as well. What you don't want is a lot of cold food, because cold causes stagnation, and stagnation makes the heat worse.
So I ask patients first how they do with vegetables. If they don't do well with them, there are plenty of other ways to get fiber in. And the bacteria need it. They need the soluble fiber to make the short-chain fatty acids that calm inflammation. Just because someone has heat doesn't mean you give them a pile of cold food. That slows things down and makes the heat worse.
What the research says
Dr. Lan's explanation has three steps. I went and looked up each one.
Step one: fiber turns into butyrate, and butyrate feeds the colon. This part is solid. In a well-known 1980 study of cells from the human colon, butyrate supplied about three-quarters of the cells' energy when it was the only fuel they had.1 In lab studies, butyrate also helps the gut lining seal up the gaps between its cells.2 One thing to keep in mind: a cup of tea has a lot less fiber than a bowl of beans, and nobody has measured how much fiber three teabags a day actually give you. Most of your fiber is going to come from your food. That's why the food advice above matters so much.
Step two: inflammation shuts down the colon's water channel. There's a water channel in the colon wall called aquaporin-3 (AQP3). It's found mostly in the colon, and it helps decide how much water stays in your stool.3 Researchers in Calgary showed that TNF, one of the main inflammation signals, turns AQP3 down in human colon cells.4 That backs up what she said, though it was done in a cell line, not in people.
Where it gets thinner. Less AQP3 means more water left in the stool, so that explains the loose side. The sluggish side doesn't fit as neatly. In rat studies, constipation from opioids actually went along with AQP3 going up, not down.3 So calming the inflammation explains why a loose, inflamed gut settles down. For the sluggish gut, I think getting things moving is doing more of the work.
San Ren Tang itself. A 2025 study in mice with colitis found the formula helped the gut lining, calmed the immune cells in the gut, and changed the gut bacteria.5 A separate animal safety study found no significant harm at high doses over 28 days.6 I couldn't find a single published human trial of San Ren Tang in English. The idea makes sense. The human evidence isn't there yet.
If you want the bigger picture on gut bacteria, I wrote about the microbiome and why your gut environment matters on the clinic blog.
How to use it
Dr. Lan's dose is three teabags a day. Here's the part people get wrong. You don't drop a teabag in a mug of hot water and let it sit like a grocery-store tea. Put the teabags in a large pot or a kettle with water and brew them until the water turns a nice yellow color. Just soaking them in hot water isn't enough to get the herbs out.
Botanical Biohacking also says San Ren Tang is a course, not something you drink forever. Plan on about two weeks, and no longer than three months, because over time it can wear down your energy. It's also not the right formula when the heat is much stronger than the damp.
She calls it low risk for most people, with one real exception. Something in the formula affects CYP3A4, the liver enzyme that clears a lot of medications. If you take anything from these five groups, check with your doctor first:
- Transplant immunosuppressants (tacrolimus, cyclosporine)
- Blood thinners (apixaban, rivaroxaban)
- Hormonal contraceptives
- Oncology agents (TKIs, irinotecan)
- HIV antiretrovirals
She also says to avoid it if you have significant liver disease or you're pregnant.
Her letter doesn't say which herb is the one. The most likely candidate is Chai Hu. Compounds from it blocked CYP3A4 in human liver samples.7 And a 2026 study out of Japan, looking at insurance records for more than 37,000 people on the antipsychotic quetiapine, found that adding a bupleurum formula went along with more side effects, mostly drowsiness and sedation.8 Quetiapine isn't on her list. I'd add it. One note for practitioners: Fa Ban Xia is traditionally not combined with aconite-family herbs.
Talk with your own practitioner before you start, especially if you take any prescription medication.
Related formulas: Wind Tea for the same damp picture in someone more run down · Warm Hearth Tea when the damp runs cold and phlegmy instead of hot.
References
- Roediger WE. Role of anaerobic bacteria in the metabolic welfare of the colonic mucosa in man. Gut. 1980;21(9):793-8. doi:10.1136/gut.21.9.793
- Peng L, et al. Butyrate enhances the intestinal barrier by facilitating tight junction assembly via activation of AMP-activated protein kinase in Caco-2 cell monolayers. J Nutr. 2009;139(9):1619-25. doi:10.3945/jn.109.104638
- Kon R, et al. Morphine-induced constipation develops with increased aquaporin-3 expression in the colon via increased serotonin secretion. Toxicol Sci. 2015;145(2):337-47. doi:10.1093/toxsci/kfv055
- Peplowski MA, et al. Tumor necrosis factor α decreases aquaporin 3 expression in intestinal epithelial cells through inhibition of constitutive transcription. Physiol Rep. 2017;5(19):e13451. doi:10.14814/phy2.13451
- Zhang S, et al. Sanren decoction ameliorates ulcerative colitis by modulating gut microbiota and macrophage polarization to enhance intestinal barrier function. Chin Med. 2025;20(1):128. doi:10.1186/s13020-025-01183-1
- Wang Q, et al. Acute toxicity and safety profile evolution of aqueous extracts of Sanren decoction using in vivo models. J Ethnopharmacol. 2022;287:114940. doi:10.1016/j.jep.2021.114940
- Liu Q, et al. Saikosaponins and the deglycosylated metabolites exert liver meridian guiding effect through PXR/CYP3A4 inhibition. J Ethnopharmacol. 2021;279:114344. doi:10.1016/j.jep.2021.114344
- Mu X, et al. Risk of adverse events associated with co-administration of quetiapine and Bupleuri Radix: a population-based cohort study. Pharmacol Res. 2026;229:108251. doi:10.1016/j.phrs.2026.108251
Further reading from Valley Health Clinic: Peak Tea and San Ren Tang · Wind Tea · A more harmonious life through microbiomes
Questions people ask
What are the benefits of San Ren Tang?
San Ren Tang is traditionally used for damp heat: heaviness, bloating, a sticky mouth without much thirst, and an afternoon slump. Dr. Lan's view is that it may support a calmer gut lining and help bowel water balance return to normal. It hasn't been tested in human trials.
What is in Peak Tea?
Ten herbs. The eight from San Ren Tang (apricot kernel, white cardamom, coix seed, magnolia bark, prepared pinellia, talc, rice-paper pith and bamboo leaf) plus bupleurum and virgate wormwood.
How do I make Peak Tea?
Use three teabags a day. Put them in a large pot or a kettle with water and brew them until the water turns a nice yellow color. Don't just steep one in a mug of hot water.
Can it help both loose and sluggish bowels?
Dr. Lan thinks so, and I see it help both in clinic. The published science explains the loose side better than the sluggish side, and the tea hasn't been tested in people.
How long can I drink Peak Tea?
Botanical Biohacking says about two weeks, and no longer than three months. It's a course, not an everyday tea.
Does Peak Tea interact with medications?
It can. Dr. Lan flags transplant immunosuppressants, apixaban and rivaroxaban, hormonal contraceptives, some cancer drugs and HIV antiretrovirals. Research on bupleurum adds quetiapine. Avoid it if you're pregnant or have significant liver disease, and check with your practitioner first.
Adapted with permission from a Botanical Biohacking practitioner letter by Dr. Xuelan Qiu (“Dr. Lan”). Will Sheppy, L.Ac., practices at Valley Health Clinic in Albany, Oregon.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Information is educational and does not replace care from your own practitioner.