Hijiki

BotanicalSeaweed

What is it

Hijiki (Sargassum fusiforme, formerly Hizikia fusiforme) is a brown seaweed used in Japanese and Korean cuisine. It is sold dried and as a supplement ingredient for mineral and fiber content.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Mineral and iodine source

Limited Evidence

Hijiki contains useful minerals, but the arsenic burden outweighs nutritional value for most people; safer seaweed alternatives exist.

How it works

Hijiki contains soluble fiber (including alginate and fucoidan), iodine, calcium, magnesium, iron, and polyphenols such as phlorotannins. Fiber components support gut health and may bind dietary fat, while iodine supports thyroid function. Some bioactive sulfated polysaccharides have shown immunomodulatory and antioxidant effects in cell models. A significant safety issue is hijiki's high content of inorganic arsenic, which has prompted food safety authorities in several countries to advise against routine consumption.

Dosage

Traditional culinary servings are small (5-10 g rehydrated). Supplement forms vary; no nutritional dose is established and routine intake is discouraged due to arsenic.

When and how to take it

Routine consumption is not advised. If consumed occasionally, treat as a small culinary garnish.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Dried hijiki

Traditional preparation; not recommended for regular use.

Rehydrated before use; arsenic remains.

Safety

Hijiki contains substantially more inorganic arsenic than other edible seaweeds. The UK Food Standards Agency, Hong Kong, Canada, and other regulators have advised against eating hijiki due to cumulative exposure risk. High iodine content can also affect thyroid function.

Who should be cautious

Avoid in pregnancy and breastfeeding due to arsenic and iodine concerns. People with thyroid disease, kidney disease, or those eating other seaweeds regularly should limit intake. Children are particularly vulnerable.

Interactions

Iodine content may interact with thyroid medications. Iodine and arsenic exposure compounds with other seaweed intake.

Food sources

Hijiki, dried

Amount
5 g (rehydrated)
%DV
—

Frequently asked questions

Is hijiki safe to eat?⌄

Multiple regulators advise against routine consumption due to high inorganic arsenic. Other seaweeds like wakame, nori, and kombu are safer.

Does rinsing remove the arsenic?⌄

Soaking and rinsing can reduce some arsenic but not enough to make regular consumption safe by current standards.

References

Hijiki on Wikidata — Wikidata link

Hijiki on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Hijiki (PubMed search) — PubMed link

Track Hijiki with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.