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Moderate evidenceGut health

Sodium Alginate

A seaweed fibre that forms a floating gel raft on top of stomach contents. It gives real short-term heartburn relief, adds little on top of a PPI, and does nothing measurable for appetite.

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What the science says

  • Symptomatic reflux relief Moderate evidence

    A meta-analysis of over-the-counter GERD therapies found alginate/antacid combinations gave up to a 60% relative benefit increase over placebo for symptom relief — the largest effect among the OTC options examined.

  • Pooled RCT results are less impressive Limited evidence

    A systematic review of 11 RCTs found individual trials favouring alginate but no statistically significant pooled difference versus placebo or antacids, and a separate meta-analysis of four RCTs found adding alginate to a PPI did not significantly improve heartburn scores.

  • No effect on appetite or satiety Limited evidence

    A randomized placebo-controlled trial in 48 overweight and obese adults found 10 days of sodium alginate had no effect on gastric emptying, satiation, calorie intake at a free-choice meal, or gut satiety hormones.

Dosage & safety

Studied doseFor reflux, 500–1,000 mg of sodium alginate (or 10–20 mL of a liquid raft formulation) after meals and at bedtime.
SafetyVery well tolerated. Liquid raft formulations can carry a substantial sodium load, which matters in heart failure and hypertension. As a viscous fibre it can slow absorption of other medicines — separate doses by about two hours.

How to take it

TimingAfter meals and at bedtime — it works by floating on stomach contents, so an empty stomach wastes it.
With food?After food, not before.
Worth knowingStay upright for 30 minutes after the bedtime dose and check the sodium content if you have heart failure or high blood pressure.

Interactions

With medications

  • all oral medications

    The gel raft is a viscous barrier that can slow or reduce absorption of anything taken with it. separate by about 2 hours

With other supplements

  • iron, minerals and other oral supplements

    Same physical barrier effect on absorption. separate by about 2 hours

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does sodium alginate work for heartburn?

Sodium alginate has moderate evidence for reflux: an analysis of over-the-counter GERD therapies found alginate/antacid combinations gave up to a 60% relative benefit increase over placebo, the largest among OTC options. Pooled RCT results are less consistent, but short-term relief is real.

Should I take alginate with a PPI?

A meta-analysis of four RCTs found adding sodium alginate to a PPI did not significantly improve heartburn scores, so the added benefit is limited. Alginate is mainly useful as a standalone short-term reliever.

When should I take sodium alginate?

Take sodium alginate after meals and at bedtime, because it forms a raft floating on stomach contents; the usual dose is 500–1,000 mg or 10–20 mL of a liquid raft formulation. Stay upright for 30 minutes after the bedtime dose.

Does sodium alginate help with weight loss or appetite?

No: a randomized placebo-controlled trial in 48 overweight and obese adults found 10 days of sodium alginate had no effect on gastric emptying, satiation, calorie intake or gut satiety hormones. The evidence for alginate and appetite is limited and negative.

Scientific references

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