TISSUE REPAIR: This image was going around, so I decided to look up the information using GROK.
Basically, what drinking this solution does is to reduce the inflammatory causing macrophages, and it promotes the regulatory and resolution type macrophages. (look below the study for a description of how
Study:** Ray SC, Baban B, Tucker MA, et al. Oral NaHCO₃ Activates a Splenic Anti-Inflammatory Pathway: Evidence That Cholinergic Signals Are Transmitted via Mesothelial Cells. *J Immunol*. 2018 May 15;200(10):3568-3586. doi: 10.4049/jimmunol.1701605. PMID: 29661827. (Epub 2018 Apr 16.)
**Links:**
– Full text (PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC5940560/
– PubMed: https://pubmed.ncbi.nlm.nih.gov/29661827/
– Journal site: https://academic.oup.com/jimmunol/article/200/10/3568/7966279
**Summary of relevant findings:**
The study tested the hypothesis that oral sodium bicarbonate (NaHCO₃) intake stimulates splenic anti-inflammatory pathways.
In rats, oral NaHCO₃ loading shifted macrophage polarization from predominantly M1 (inflammatory) to M2 (regulatory) phenotypes and increased FOXP3⁺CD4⁺ T-lymphocytes in the spleen, blood, and kidneys.
Similar anti-inflammatory changes in macrophage polarization were observed in human blood after NaHCO₃ ingestion.
In the human portion, 12 healthy participants (6 men, 6 women; mean age 27 ± 2 years) received a single dose of 2 g NaHCO₃ dissolved in 250 ml of bottled water.
An additional 6 participants received equimolar NaCl in 250 ml water as controls.
Blood was collected at baseline and at 1, 2, and 3 hours post-ingestion (10 of 12 NaHCO₃ subjects had the 3-hour draw).
Flow cytometry showed a significant Treatment × Time effect on M1 macrophages (p = 0.0004) and TNFα-positive neutrophils (p = 0.0146), with greater reductions in these inflammatory cells after NaHCO₃ versus NaCl.
The largest decreases occurred at 2 and 3 hours after NaHCO₃. NaHCO₃ also increased the percentage of blood leukocytes identified as M2 macrophages (p = 0.00165).
The authors concluded that oral NaHCO₃ activates a splenic anti-inflammatory pathway, with evidence that the signals are transmitted to the spleen via a neuronal-like function of mesothelial cells
Q. What are the discussions regarding why the macrophages would be increased when ingesting this?
A.
Macrophages are not a single type of cell with one fixed role. They can polarize into different functional phenotypes depending on signals in their environment.
In the 2018 study (Ray et al., *Journal of Immunology*), the key observation was a **shift in polarization**, not a simple increase in pro-inflammatory activity:
– **M1 macrophages** (classically activated) decreased. These are the more pro-inflammatory subset. They produce mediators such as TNF-α and are associated with host defense and driving inflammatory responses.
– **M2 macrophages** (alternatively activated / regulatory) increased.
These are linked to resolution of inflammation, tissue repair, and anti-inflammatory functions.
They tend to produce mediators that dampen inflammation (e.g., IL-10) and support cleanup and repair.
The authors describe this as a shift “from predominantly M1 (inflammatory) to M2 (regulatory) phenotypes.” The same directional change was seen in rat spleen, blood, and kidney, and in circulating cells in the small human arm of the study after a single 2 g dose of NaHCO₃ in 250 ml water.
### Proposed mechanism in the paper
The researchers proposed that oral NaHCO₃ activates a **splenic anti-inflammatory pathway** that is part of (or closely related to) the cholinergic anti-inflammatory pathway. In brief:
– Ingesting the bicarbonate solution is thought to prompt the stomach to increase acid production.
– This appears to trigger signaling that reaches the spleen, involving mesothelial cells (the thin lining cells covering the spleen and lining body cavities). These cells stained positive for neuronal markers (PGP9.5) and acetylcholine esterase and had ultrastructural features resembling neuronal elements.
– The net effect in the spleen is a more anti-inflammatory immune cell profile (fewer M1-like macrophages, more M2-like macrophages, and more regulatory T cells).
– Interventions that disrupted the mesothelial connections or cut the vagal nerves below the diaphragm abolished or reduced the response in the rat experiments, supporting the idea that these signals are required.
In short, the increase was specifically in the M2 (anti-inflammatory/regulatory) subset, while the M1 (pro-inflammatory) subset declined. Macrophages as a group perform both inflammatory and resolution/cleanup roles; the phenotype determines which set of functions predominates at a given time. The study frames the NaHCO₃ effect as pushing the balance toward the resolution side via a spleen-centered cholinergic pathway.