I recently wrote about the altered cytokine profile that is seen in people with Long Covid. Cytokines are immune hormones. Cytokine levels normally change in response to challenges to our immune systems, but they can also get stuck in patterns that cause illness.
In the case of Long Covid, that abnormal pattern of cytokines involves elevated levels of IL-2 and IL-17 (which are generally inflammatory), and low levels of IL-4 and IL-10 (anti-inflammatory). The team that did that research pointed to the obvious possibility that normalizing these cytokine levels might lead to improvement in Long Haulers. We don’t know for sure that balanced cytokines are a cause of long covid, but it seems to be.
Rehmannia and Acetoside
Rehmannia root is one of the workhorses of Asian herbal medicine; it is one of the 50 most commonly used herbs. It contains a compound called acetoside1 that has been shown to stimulate B cells in the immune system to produce more IL-4.
“Acteoside promotes B cell-derived IL-10 production and ameliorates autoimmunity.” Journal of Leukocyte Biology, 31 May 2022. PMID 35638582
Caveats: this study was done in human cells in a test tube, and in intact mice. The acetoside boosted IL-10 production in both cases, but there might be differences in intact humans (the liver and kidneys might rapidly reduce the amount of acetoside in circulation, while in a test tube, acetoside levels might stay higher for longer). The researchers did find that acetoside was absorbed when administered orally, and it moved into lymphoid organs, where it would be active.
Compounds found in Rehmannia
Acetoside
Catalpol & related iridoid compounds
Polysaccharides
In addition to acetoside, there are two other classes of molecules of biological interest. This includes catalpol and related compounds, and some unusual polysaccharides.
Reduces Autoimmune Activity
Anti-Thrombotic Activity
Modulates Angiotensis II
Toxicity and Safety
Rehmannia is sometimes called Chinese Foxglove; this is due to the fact that the leaves and flowers on the two plants look somewhat similar at first glance. Rehmannia is not botanically related to what westerners often call foxglove (Digitalis purpurea). While Digitalis species contain compounds that can dangerously affect the heart if the dose is too high, those compounds are not present in Rehmannia.
The Google snippet on the safety of this herb points to a website that says it is “Very safe” — and that the most common side effects include gastrointestinal distress in some people due to compounds that are similar to what are found in beans or Jerusalem artichokes. I have read a few other other potential precautions, and advise anyone with specific health conditions (or on prescription medicines) to do more research to determine if there might be some specific concerns. This is not an herb that is tied to many adverse effects, but any food or herb has the potential to have something to be aware of.
In general, I am not very trusting of agricultural products from China (including herbs). Buying it from a reputable company that does QA/QC on the herbs that they import is a good idea - it reduces the chances of getting a contaminated or adulterated product.
Rehmannia Herb
Rehmannia is a relatively inexpensive herb - one online source I trust had it for less than $20 per pound.
You can grow Rehmannia yourself, but the processing is a bit involved and tricky. Rehmannia root is typically first soaked in vinegar or wine for a while, and then repeatedly steamed and dried. This changes the properties of the herb. Ordinary dried rehmannia is sometimes used as a medicine, but is considered harsher and not as tonic as steamed rehmannia.
Acetoside is technically a caffeoyl phenylethanoid glycoside. Here is the structure: