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Alginate's affects on improving reflux has been known about for decades. Initial scientific studies on how it improves reflux were conducted in the 1980s.
Alginates are natural polysaccharide polymers isolated from brown seaweed (Phacophycae) and is classified as dietary fiber. Their ability to form viscous solutions and gels have led to their extensive use in foods, cosmetics, and pharmaceutical products for over one century.
As it pertains to reflux, perhaps the most interesting study on alginate was published in 1988 whereby alginate was labelled with 111In radioisotope in order to "see" what happens in the stomach.
"acid concentrations less than 0.05 N diminished raft formation. In vivo, raft formation was significantly better in normal subjects who ingested dilute acid with the labeled alginate/antacid than in subjects who ingested the labeled alginate/antacid with plain water. Gastric emptying of the labeled alginate was also slowed by the presence of acidified gastric contents. These results suggest that the formation of an effective alginic acid antireflux barrier requires acidic gastric contents." [link]As such, if alginate is used, a patient should probably not ingest any proton pump inhibitors (nexium, prevacid, prilosec, etc) or H2 blockers (zantac, pepcid, axid, etc) for best effect which may seem counterintuitive.
In the presence of gastric acid, alginate has been found to precipitate forming a thick gel. Such alginate formulations usually contain sodium or potassium bicarbonate; in the presence of gastric acid, the bicarbonate is converted to carbon dioxide which becomes entrapped within the gel precipitate converting it into a foam which floats on the surface of the gastric contents, much like a raft on water. Both in vitro and in vivo studies have demonstrated that alginate-based rafts can entrap carbon dioxide, as well as antacid components contained in some formulations, thus providing a relatively pH-neutral barrier.
Another factor that affects the alginate raft is the presence of calcium and aluminum. Calcium increases raft strength (becomes more solid) while aluminum reduces raft strength (becomes more gel-like).
To summarize, for effective alginate treatment of reflux, acid as well as bicarbonate needs to be present. The level of solidity is determined by calcium and aluminum concentrations.
Alginate in ideal concentrations can be found in Gaviscon Advance sold only in Europe. Be aware that plain "Gaviscon" which is sold in the United States is NOT the same as Gaviscon Advance. However, it can be purchased on Amazon with delivery in a few weeks.
How to Make Gaviscon Advance DIYHowever, one enterprising Amazon user figured out a way to make their own Gaviscon Advance equivalent using ingredients readily available in the United States. Given supplies are purchased in bulk, it ends up being cheaper as well over the long term.
Gaviscon Advance is composed of 1000 mg sodium alginate, 426 mg sodium bicarbonate, and 650 mg calcium carbonate.
So one can purchase the following "ingredients" that make up Gaviscon Advance:
• WillPowder Sodium Alginate 16 ounce Container
• Baking Soda (this is the sodium bicarbonate)
• TUMS (this is the calcium carbonate)
To make a "single" dose to be taken after a meal, one would mix:
• 1/4 teaspoon of sodium alginate
• 1/8 teaspoon of baking soda (1/8 teaspoon of baking soda is ~500-600 mg)
• Using a mortar and pestle, crush one 750 mg chewable TUMS antacid tablet into a powder
Mix all of this together (you can use a frother) with a few ounces of water to create a slurry which you can than swallow after a meal.
Quite a bit more steps than just purchasing Gaviscon Advance, but one can also request a Compound Pharmacy to do all this for you with each dose contained within a packet. WeCare Pharmacy in Warrenton, VA does this for patients in our area.
Use of 111In-labeled alginate to study the pH dependence of alginic acid anti-esophageal reflux barrier. Int J Rad Appl Instrum B. 1988;15(5):563-71.
Review article: alginate-raft formulations in the treatment of heartburn and acid reflux. Aliment Pharmacol Ther. 2000 Jun;14(6):669-90.
An alginate-antacid formulation (Gaviscon Double Action Liquid) can eliminate or displace the postprandial 'acid pocket' in symptomatic GERD patients. Aliment Pharmacol Ther. 2011 Jul;34(1):59-66. doi: 10.1111/j.1365-2036.2011.04678.x. Epub 2011 May 3.