Also known as: alginate, E401, kelp alginate
Sodium Alginate
·By Croix
What is sodium alginate?
Sodium alginate is a natural polymer extracted from brown seaweed (kelp). It's a long chain of two sugar-acid building blocks — mannuronic and guluronic acid — linked together in patterns that determine how the alginate behaves in solution.
In the food industry it's used as a thickener, gelling agent, and (in molecular gastronomy) the basis for spherification. In sports nutrition, it's the active ingredient in Maurten's hydrogel system — combined with pectin, it forms a soft gel in stomach acid.
How does it work in a sports drink?
When sodium alginate and pectin enter the acidic environment of the stomach (pH 1.5–3.5), the alginate's sugar-acid groups protonate and the polymer chains cross-link with each other and with pectin, forming a soft gel. The cross-linking chemistry is well-established food science. Sutehall et al. 2020 reports a downstream consequence of this format — at rest, in 8 healthy men, the alginate+pectin hydrogel beverage emptied the stomach faster than a matched maltodextrin+fructose control (~21 vs 37 min to half-empty), with no difference in serum glucose, insulin, or NEFA.
Maurten's claim is that this gel encapsulates the maltodextrin and fructose, allowing the drink to clear the stomach faster at high carb concentrations and reducing GI distress at race-pace intake rates. Independent matched-dose comparisons reviewed in Podlogar & Wallis 2022 have not reliably reproduced a performance, oxidation, or GI-tolerance benefit over a non-hydrogel drink with the same carbs and ratio.
How do I use it at home?
We don't recommend buying sodium alginate for DIY sports drinks. The hydrogel technology is interesting and the chemistry is real, but the matched-dose evidence does not currently support paying a price premium for the format.
If you specifically want to recreate the Maurten experience for a single race or curiosity exercise: search out food-grade sodium alginate (used in molecular gastronomy) and pectin, and follow the proportions in any one of the published Maurten replication recipes online. The site's stance is that you'll get the same physiology from a plain 1:0.8 maltodextrin-fructose drink at a fraction of the cost.
Importantly: alginate-pectin gel formation is pH-dependent. Mixing alginate into water at ordinary pH won't gel; the gel only forms when it hits stomach acid. Don't expect the dry-mix shaker to behave like a Maurten when first dissolved.
DIY teardowns that use sodium alginate
Linked above— all walk through how sodium alginatefits into the specific commercial product's formulation.