• That little box you put in the refrigerator and freezer to prevent odoriferous gases from tainting your food may hold the key to reducing the destructive inflammation of autoimmune diseases like rheumatoid arthritis. New evidence from investigators at the Medical College of Georgia (MCG) shows how a cheap, over-the-counter antacid solution of sodium bicarbonate (commonly referred to as baking soda) can encourage the spleen to promote an anti-inflammatory environment that could be therapeutic in the face of inflammatory disease. Findings from the new study were published recently in the Journal of Immunology, in an article entitled “Oral NaHCO3 Activates a Splenic Anti-Inflammatory Pathway: Evidence That Cholinergic Signals Are Transmitted via Mesothelial Cells.”

  Previous studies have shown that when rats or healthy people drink a solution of sodium bicarbonate, it becomes a trigger for the stomach to make more acid to digest the next meal and for little-studied mesothelial cells sitting on the spleen to tell the fist-sized organ that there's no need to mount a protective immune response.

  The splenic response to pH shift is that “it's most likely a hamburger, not a bacterial infection," noted senior study investigator Paul O'Connor, Ph.D., a renal physiologist in the MCG department of physiology.

  Mesothelial cells line body cavities, like the digestive tract, and they also cover the exterior of organs to quite literally keep them from rubbing together. About a decade ago, it was found that these cells also provide another level of protection—microvilli that sense the environment and warn the organs they cover that there is an invader and an immune response is needed.

  The MCG researchers believe that drinking baking soda tells the spleen—which is part of the immune system where some white blood cells, like macrophages, are stored—to go easy on the immune response. "Certainly, drinking bicarbonate affects the spleen, and we think it's through the mesothelial cells," Dr. O'Connor noted.

  Interestingly, the research team found that after drinking water with baking soda for two weeks, the population of macrophages in the spleen, kidneys, and blood shifted from primarily those that promote inflammation, called M1, to those that reduce it, called M2. Macrophages, perhaps best known for their ability to consume garbage in the body, like debris from injured or dead cells, are often the immune systems first responders to a call for assistance.

  While studying hypertension and chronic kidney disease in mice, Dr. O’Connor and his colleagues got to thinking about baking soda. "We started thinking, how does baking soda slow progression of kidney disease?" Dr. O'Connor remarked.

  One of the many functions of the kidneys is balancing important compounds like acid, potassium, and sodium. With kidney disease, there is impaired kidney function, and one of the resulting problems can be that the blood becomes too acidic. Significant consequences can include increased risk of cardiovascular disease and osteoporosis.

  "It sets the whole system up to fail basically," Dr. O'Connor stated. Clinical trials have shown that a daily dose of baking soda can not only reduce acidity but actually slow progression of the kidney disease, and it's now a therapy offered to patients.

  After persistent experimentation, the MCG team noticed the anti-inflammatory impact of baking soda and then a hypothesis began to unfold, as the researchers saw reduced numbers of M1s and increased M2s in their kidney disease model after consuming the common compound. When the scientists looked at a rat model without actual kidney damage, they saw the same response.

  "The shift from inflammatory to an anti-inflammatory profile was happening everywhere," Dr. O'Connor said. "We saw it in the kidneys, we saw it in the spleen, now we see it in the peripheral blood."

  The shifting landscape, Dr. O’Connor said, is likely due to increased conversion of some of the proinflammatory cells to anti-inflammatory ones coupled with actual production of more anti-inflammatory macrophages. The scientists also saw a shift in other immune cell types, like more regulatory T cells, which generally drive down the immune response and help keep the immune system from attacking our own tissues. That anti-inflammatory shift was sustained for at least four hours in humans and three days in rats.

  "We think the cholinergic (acetylcholine) signals that we know mediate this anti-inflammatory response aren't coming directly from the vagal nerve innervating the spleen, but from the mesothelial cells that form these connections to the spleen," Dr. O'Connor commented.

  Dr. O'Connor hopes drinking baking soda can one day produce comparable results for people with autoimmune disease.

  "You are not really turning anything off, or on, you are just pushing it toward one side by giving an anti-inflammatory stimulus," Dr. O’Connor concluded. "It's potentially a really safe way to treat inflammatory disease."