Short answer: a homemade alginate raft can work in principle — the chemistry isn’t complicated — but getting it to match Gaviscon Advance is much harder than it looks, and for most people it isn’t worth the effort. A real raft needs three things happening at once: sodium alginate to form the gel, a carbonate to generate the carbon dioxide bubbles that make it float, and ideally calcium to knit the gel together into something strong enough to hold. You can approximate that at your kitchen counter with food-grade sodium alginate and a pinch of bicarbonate of soda. What you can’t easily replicate is the strength and staying power of the commercial raft, which is exactly the part that matters.
I get why people ask. Gaviscon Advance is the one over-the-counter product with genuinely good evidence for silent reflux, and if you’re using it several times a day, the cost adds up. So the DIY question is fair. Below I’ll explain precisely how the raft works, what a homemade version would actually need, a sensible way to try it, and — honestly — why I still reach for the bottle myself.
One thing up front: none of this is medical advice, and if you’re on a sodium-restricted diet for blood pressure, heart or kidney reasons, the DIY route is not for you, because you can’t control the sodium load the way a formulated product does.
Key Takeaways
- An alginate raft floats on top of your stomach contents and physically blocks reflux — it doesn’t reduce acid, it gets in the way of it.
- Gaviscon Advance works because it’s packed with sodium alginate and forms a strong, long-lasting raft; independent testing found it held its neutralising raft for about 93 minutes versus 5–27 minutes for weaker products.
- A homemade raft needs three ingredients working together: sodium alginate (the gel), a bicarbonate/carbonate (the CO₂ that makes it float), and ideally a calcium source (to strengthen the gel).
- You can buy food-grade sodium alginate cheaply, and a basic DIY raft is genuinely possible — but matching the commercial raft’s alginate concentration and gel strength at home is the real challenge.
- Alginates are proven: a meta-analysis of 14 trials found they quadrupled the odds of resolving reflux symptoms versus placebo or antacids, and a randomised trial showed Gaviscon Advance improved silent reflux (LPR) scores.
- The big practical risks of DIY are inconsistent dosing, an uncontrolled sodium load, and a weak raft that simply doesn’t hold.
- For most people, Gaviscon Advance is cheap enough and reliable enough that DIY isn’t worth it — but understanding the chemistry helps you use it better.
How an Alginate Raft Actually Works
This is the bit worth understanding, because it explains everything about why DIY is fiddly. Unlike a PPI or an antacid, an alginate doesn’t touch your acid levels at all. It works mechanically. When alginate meets stomach acid, it turns into a gel; at the same time, a carbonate ingredient reacts with the acid to release carbon dioxide, and those CO₂ bubbles get trapped in the gel and make the whole thing float. The result is a raft — a spongy gel layer sitting right on top of your stomach contents [Kim, Journal of Neurogastroenterology and Motility, 2016].
Why does floating matter? Because after a meal, a pool of especially acidic juice collects at the top of the stomach, right by the valve into the esophagus — the “acid pocket.” That pocket is what refluxes first. The raft physically occupies that space, so when reflux happens, what comes up is neutral-ish raft gel rather than a jet of acid and pepsin. For silent reflux that’s the whole point, since it’s the pepsin riding up with the acid that does the damage in your throat. I go deeper into this whole class of treatment in my guide to alginates for acid reflux.
Independent lab work shows the three reactions have to be balanced: the alginate turning to gel, the carbonate producing CO₂, and calcium carbonate releasing calcium ions that cross-link the gel into something firm. When researchers compared products head to head, Gaviscon Advance came out on top precisely because it had the highest alginate content in its raft and held a neutralising raft for around 93 minutes, while several weaker antacid-style products managed only 5 to 27 minutes [Dettmar et al., Drug Development and Industrial Pharmacy, 2018]. That number — 93 minutes versus single digits — is the whole ball game, and it’s what a DIY version has to compete with.
Does the Store-Bought Version Even Work? (Yes)
Before spending effort on a copy, it’s worth knowing the original is one of the few OTC reflux products I actually rate. A systematic review and meta-analysis of 14 trials with over 2,000 people found alginate-based therapies increased the odds of resolving reflux symptoms more than fourfold compared with placebo or plain antacids (odds ratio 4.42) [Leiman et al., Diseases of the Esophagus, 2017]. And for the throat-based silent reflux I focus on, a randomised trial of Gaviscon Advance in 49 LPR patients found significantly better symptom and examination scores than no treatment — Reflux Symptom Index scores dropped to 11.2 versus 16.8 in controls at two months [McGlashan et al., European Archives of Oto-Rhino-Laryngology, 2009]. So the target you’re trying to reproduce at home is a genuinely effective one. More on how I use it in my full Gaviscon Advance breakdown.
What a DIY Alginate Raft Actually Needs
If you want to build a raft from scratch, you need to supply each part of that three-reaction system:
1. Sodium alginate (the gel-former). This is the active ingredient. It’s a natural extract from brown seaweed, sold cheaply as a food-grade powder for molecular gastronomy (it’s what makes those juice “spheres” in fancy restaurants). This is non-negotiable — without alginate there’s no raft, just fizz.
2. A carbonate or bicarbonate (the float). Bicarbonate of soda (sodium bicarbonate) reacts with your stomach acid to release the CO₂ that makes the gel buoyant. Without it you get a gel that sinks instead of floating on the acid pocket — useless for reflux.
3. Calcium (the strengthener) — the part people skip. Calcium ions are what turn a soft, floppy gel into a firm raft that holds together and lasts. Calcium carbonate does double duty here: it adds calcium and contributes to the CO₂ reaction. A naive recipe of just alginate plus baking soda leaves this out, which is a big reason homemade rafts tend to be weak and short-lived compared with the real thing.
You can see why the commercial product exists. Balancing those three so the raft is strong, floats reliably, and lasts an hour and a half is a formulation problem, not a kitchen one.
A sensible way to try it
If you still want to experiment, the simplest reasonable approach is a small amount of food-grade sodium alginate (roughly half a teaspoon) stirred thoroughly into a glass of water until fully dissolved — it’s slow to hydrate, so give it time and don’t leave lumps — taken after a meal, followed by a small pinch of bicarbonate of soda. The alginate forms the gel; the bicarbonate meeting your stomach acid supplies the lift. Some people add a small amount of a calcium carbonate supplement (a plain chewable calcium tablet) to firm up the raft, which brings it closer to how the real product is built.
Start small, take it sitting upright after eating, and don’t chase the sensation of a “big” dose — more powder just makes a thicker sludge, not a better raft. And treat this as an occasional experiment, not a daily regimen you self-formulate, for the sodium reason below.
Why It Won’t Match Gaviscon Advance
Even done carefully, a homemade raft has three built-in disadvantages:
Alginate concentration. The commercial product is dense with alginate, and raft strength tracks closely with how much alginate ends up in the raft [Dettmar et al., Drug Development and Industrial Pharmacy, 2018]. Hitting that concentration with a home scoop, in a way that actually gels rather than clumps, is hard.
Raft durability. That 93-minute neutralising window is the product of precise formulation. A DIY raft realistically holds for a fraction of that, meaning you’d need to redose far more often to get the same protection.
Consistency. Every glass you make by hand is slightly different. The manufactured product is identical every dose — which matters when you’re relying on it to protect your throat overnight.
The Safety Bit: Sodium
This is the one genuine caution. Both sodium alginate and bicarbonate of soda add sodium, and a homemade version gives you no control over how much. If you have high blood pressure, heart failure, or kidney problems — or you’re on a low-sodium diet for any reason — don’t freelance this; the sodium load can matter. (This is also why I don’t lean on plain baking soda for heartburn as a routine fix.) Gaviscon Advance also contains sodium, but at least it’s a known, fixed quantity per dose. If sodium is a concern for you, that predictability is worth a lot.
So Should You Bother?
Here’s my honest take after years of using alginates for my own reflux. The DIY raft is a genuinely interesting bit of chemistry, and knowing how it works makes you a smarter user of the real thing — you’ll understand why you take it after meals, why sitting upright helps, and why it protects the throat rather than killing acid. But as a replacement? For most people, no. Gaviscon Advance is inexpensive, reliable, dose-controlled, and forms a far stronger raft than anything I can make at the counter. The effort-to-benefit ratio just doesn’t favour the homemade version unless you have a specific reason — and even then I’d rather people spend that energy on the eating pattern that reduces how often they need a raft at all.
If you’re comparing options rather than making them, it’s also worth reading Reflux Gourmet vs Gaviscon and how the raft products stack up before you decide anything.
Conclusion
A homemade alginate raft is possible and the science behind it is real: sodium alginate to gel, bicarbonate to float it, calcium to firm it up. But the thing that makes Gaviscon Advance actually work — a dense, strong raft that holds for around an hour and a half — is precisely what’s hardest to reproduce in a glass, and the uncontrolled sodium makes daily DIY a poor idea for anyone who needs to watch their salt. Use the knowledge to get more out of the product, not to replace it.
And remember that a raft, homemade or bottled, is a barrier, not a cure — it manages a reflux event after the fact. The bigger wins come from reducing how often reflux happens in the first place, which is what the Wipeout Diet Plan is built to do. I designed it around LPR, the stubborn throat-based form where a raft matters most, but because it targets the same underlying reflux mechanics it works just as well for classic GERD and heartburn. If you want the lighter starting point, the Wipeout Food Reference Guide is the essential companion — it maps out which foods and drinks are safe for reflux and where they sit on the pH scale, so you’re leaning on the raft less and less over time.
Frequently Asked Questions
Can you make your own Gaviscon at home?
You can make something that works on the same principle — sodium alginate to form a gel, bicarbonate of soda to make it float, and optionally a little calcium carbonate to strengthen it. What you can’t easily do is match Gaviscon Advance’s alginate concentration and raft durability, which is what makes the commercial product effective. It’s a fair experiment, but not a true replacement.
What is the active ingredient in Gaviscon Advance?
The key active ingredient is sodium alginate, present at a high concentration, alongside potassium bicarbonate. The alginate forms the gel raft and the bicarbonate generates the carbon dioxide that makes it float on top of the stomach contents. It’s the high alginate content that gives Gaviscon Advance its strong, long-lasting raft.
Where do you get sodium alginate?
Food-grade sodium alginate is sold cheaply as a powder for molecular gastronomy and home cooking, online and in some specialty food shops — it’s the same ingredient used to make juice “spheres.” Make sure it’s food-grade. On its own, though, it won’t float; you need a bicarbonate source to form a proper raft.
Is homemade alginate safe?
Food-grade sodium alginate and bicarbonate of soda are generally safe in small amounts for healthy people, but a homemade mix gives you no control over the sodium load. If you have high blood pressure, heart failure, kidney disease, or you’re on a low-sodium diet, avoid the DIY route and use a dose-controlled product instead. This isn’t medical advice, so check with your doctor if you’re unsure.
Does an alginate raft reduce stomach acid?
No — and that’s the point. An alginate raft doesn’t change how much acid you make; it forms a physical barrier that floats on top of your stomach contents and gets in the way of reflux. That’s why it can work even when acid levels are normal, and why it’s useful for silent reflux where the problem is refluxate reaching the throat rather than excess acid.
When should I take an alginate raft?
After meals and at bedtime, because that’s when the post-meal acid pocket forms and when reflux is most likely. Taking it after eating (not before) means the raft forms on top of a full stomach, right where it needs to sit. Staying upright for a while afterwards helps the raft settle in place.
Is Gaviscon Advance worth the money over DIY?
For most people, yes. It’s inexpensive, forms a much stronger and longer-lasting raft than a homemade version, delivers a consistent dose every time, and gives you a known, fixed sodium content. Unless you have a specific reason to experiment, the reliability is worth far more than the small saving from DIY.
Research & References
- [Kim, Journal of Neurogastroenterology and Motility, 2016] — Explains how an alginate raft forms in the stomach: the gel floats because trapped carbon dioxide (released when a carbonate reacts with gastric acid) lowers its density below that of gastric fluid.
- [Dettmar et al., Drug Development and Industrial Pharmacy, 2018] — Head-to-head lab comparison of alginate antacid products; Gaviscon Advance had the highest alginate content in its raft and maintained neutralisation for about 93 minutes, versus 5–27 minutes for weaker products.
- [Leiman et al., Diseases of the Esophagus, 2017] — Systematic review and meta-analysis of 14 trials (over 2,000 subjects) finding alginate therapy increased the odds of resolving GERD symptoms more than fourfold versus placebo or antacids (odds ratio 4.42).
- [McGlashan et al., European Archives of Oto-Rhino-Laryngology, 2009] — Randomised trial of Gaviscon Advance in 49 patients with laryngopharyngeal reflux; the treated group had significantly better Reflux Symptom Index and Reflux Finding Scores than untreated controls.
David Gray
12 years living with LPR · Consultant & researcher
I've lived with LPR for twelve years — the misdiagnoses, the PPI courses that did nothing, the slow work of figuring out what actually helps. Wipeout Reflux is where I translate the research into plain terms for people stuck in the same place. Every claim here is sourced to peer-reviewed work, and I consult one-to-one with LPR sufferers.