# Sargassum fusiforme (Hijiki)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/sargassum-fusiforme
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-29
**Evidence Score:** 2 / 10
**Category:** Marine-Derived
**Also Known As:** Hijiki, Hizikia fusiformis, Sea Oak, Brown Seaweed, Sargassum fusiforme, Korean Hijiki, Japanese Hijiki, Chinese Sea Vegetable, Fucoidan Seaweed

## Overview

Hijiki (Sargassum fusiforme) is a brown seaweed containing bioactive compounds like SP-4 polysaccharides and 24S-saringosterol. These compounds may provide [antiviral](/ingredients/condition/immune-support) effects through HIV-1 fusion inhibition and cholesterol management via LXR-mediated pathways.

## Health Benefits

• Potential anti-viral activity: In vitro studies showed SP-4 fraction inhibited HIV-1 fusion and reverse transcriptase (preliminary evidence only)
• Cholesterol management: Contains selective LXR agonist sterols like 24S-saringosterol that may lower cholesterol via LXR-mediated transactivation (animal/in vitro evidence)
• [Anti-inflammatory](/ingredients/condition/inflammation) effects: Rich in phlorotannins (fuhalol-type) showing anti-inflammatory properties in preclinical models (no human trials)
• Mineral supplementation: High in calcium (0.87-1.17%), iron (14.3-47.6 mg/100g DW), and zinc (1.5-1.6 mg/100g DW) (compositional data only)
• Potential anti-obesity effects: Noted in pharmacological reviews but limited to animal/in vitro models without human trial specifics

## Mechanism of Action

SP-4 polysaccharide fractions from hijiki inhibit HIV-1 fusion and reverse transcriptase activity in laboratory studies. The sterol compound 24S-saringosterol acts as a selective liver X receptor (LXR) agonist, promoting LXR-mediated transactivation pathways involved in cholesterol homeostasis and lipid [metabolism](/ingredients/condition/weight-management).

## Clinical Summary

Current evidence for hijiki is limited to preliminary in vitro studies examining specific bioactive fractions. Laboratory research demonstrated SP-4 polysaccharides' [antiviral](/ingredients/condition/immune-support) properties against HIV-1, while sterol analysis identified LXR agonist activity of 24S-saringosterol. No human clinical trials have been conducted to establish therapeutic efficacy, safety profiles, or optimal dosing protocols for hijiki supplementation.

## Nutritional Profile

Per 100 g dry weight (approximate values, varying by harvest location and season): Protein: 7–12 g (contains all essential amino acids, though limiting in methionine and cysteine; digestibility moderate due to cell-wall polysaccharides). Total dietary fiber: 32–60 g (predominantly soluble: alginates 15–30 g, fucoidans 5–15 g; insoluble: cellulose 3–8 g). Fat: 1–5 g (rich in polyunsaturated fatty acids; EPA [eicosapentaenoic acid, C20:5 n-3] ~0.1–0.5 g; arachidonic acid [C20:4 n-6] present in smaller amounts; also contains fucosterol ~50–200 mg and 24S-saringosterol, a selective LXRβ agonist sterol at trace-to-low mg levels). Carbohydrates (non-fiber): 20–40 g (including mannitol ~5–10 g as a sugar alcohol). Minerals (notably high): Calcium 600–1400 mg; Iron 30–60 mg (primarily non-heme, bioavailability enhanced by co-consumed vitamin C but reduced by alginate and phytate analogs); Magnesium 500–900 mg; Iodine highly variable, typically 20–50 mg (can exceed 100 mg in some samples — caution for [thyroid](/ingredients/condition/hormonal)-sensitive individuals; bioavailability is high as iodide); Potassium 4000–6000 mg; Sodium 1500–4000 mg; Phosphorus 40–80 mg; Zinc 1–4 mg; Manganese 1–5 mg. CAUTION: Inorganic arsenic content is notably high (typically 50–120 mg/kg dry weight), prompting food safety advisories in several countries (UK FSA, EU EFSA) recommending limited or no consumption. Vitamins: β-carotene (provitamin A) 1–5 mg; Vitamin K1 ~60–80 µg; Vitamin B2 (riboflavin) 0.3–0.6 mg; Folate 100–200 µg; Vitamin C 5–15 mg (degrades significantly upon drying); Vitamin E (α-tocopherol) 1–3 mg; Niacin 1–3 mg. Bioactive compounds: Fucoidans (sulfated polysaccharides, 5–15 g/100 g dry wt, MW range 20–200 kDa; exhibit [immunomodulatory](/ingredients/condition/immune-support), anticoagulant, and potential anti-viral properties; oral bioavailability is low due to high molecular weight but partial absorption of lower-MW fragments occurs); Phlorotannins (fuhalol-type and phlorethol-type polyphenols, ~0.5–3 g/100 g dry wt; demonstrate [antioxidant](/ingredients/condition/antioxidant), [anti-inflammatory](/ingredients/condition/inflammation), and α-glucosidase inhibitory activity; bioavailability is limited, with most activity likely exerted locally in the GI tract); Fucoxanthin (carotenoid, ~0.01–0.1 mg/100 g dry wt in hijiki — much lower than in Undaria or Laminaria species; lipid-soluble, bioavailability improved with dietary fat co-ingestion, metabolized to fucoxanthinol and amarouciaxanthin A); Laminaran (β-1,3-glucan, 1–5 g/100 g dry wt; potential [prebiotic](/ingredients/condition/gut-health) and immunostimulatory effects); Sulfated polysaccharide fraction SP-4 (characterized in HIV studies, specific to Sargassum fusiforme, inhibited HIV-1 fusion and reverse transcriptase in vitro at µg/mL concentrations — oral bioavailability and in vivo relevance unknown). Bioavailability notes overall: Mineral bioavailability is modulated by the high alginate and fucoidan content, which can chelate divalent cations (Ca²⁺, Fe²⁺, Zn²⁺), potentially reducing absorption by 20–50%. Iodine is readily bioavailable. The high inorganic arsenic content is also highly bioavailable, making risk-benefit assessment critical. Soaking and boiling hijiki before consumption can reduce both arsenic and excess iodine by 30–70%, though it also leaches water-soluble vitamins and minerals.

## Dosage & Preparation

No clinically studied dosage ranges for human use are reported. Studies mention extracts with varying fucosterol content (0.249-1.067 mg/g) but without established dosing protocols. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Hijiki consumption has been associated with elevated arsenic levels, as this seaweed can bioaccumulate inorganic arsenic from seawater. Several countries including the UK and Canada have issued advisories limiting hijiki consumption due to arsenic contamination concerns. Pregnant and breastfeeding women should avoid hijiki due to potential arsenic toxicity risks. No specific drug interactions have been documented, though the iodine content may affect [thyroid](/ingredients/condition/hormonal) medications.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses on Sargassum fusiforme were identified in the research. Evidence is limited to in vitro and animal studies, with one in vitro study isolating fraction SP-4 that showed HIV-1 inhibition activity (no PMID available).

## Historical & Cultural Context

In traditional East Asian medicine (Korean, Japanese, Chinese systems), Hijiki has been used for centuries as a nutrient-dense food for mineral supplementation (calcium, iodine, magnesium) and general health promotion. Specific historical durations or traditional indications are not detailed in available sources.

## Synergistic Combinations

Kelp, Wakame, Kombu, Dulse, Spirulina

## Frequently Asked Questions

### What is the arsenic content in hijiki seaweed?

Hijiki contains significantly higher arsenic levels than other seaweeds, with some samples showing 35-100 times more inorganic arsenic than the WHO safety limit. This has led to consumption advisories in multiple countries.

### How does hijiki compare to other seaweeds for health benefits?

While hijiki contains unique SP-4 polysaccharides and LXR agonist sterols, its high arsenic content makes it less favorable than alternatives like nori or wakame. Other seaweeds provide similar mineral content without the arsenic risk.

### What is the recommended dosage for hijiki supplements?

No standardized dosage exists for hijiki supplements due to limited clinical research and safety concerns regarding arsenic content. Most health authorities recommend avoiding regular hijiki consumption rather than establishing safe intake levels.

### Can hijiki help lower cholesterol levels?

Laboratory studies suggest hijiki's 24S-saringosterol compound may influence cholesterol through LXR pathway activation. However, no human trials have confirmed cholesterol-lowering effects, and arsenic risks outweigh potential benefits.

### Is hijiki safe for people with thyroid conditions?

Hijiki's high iodine content may interfere with thyroid function and medications like levothyroxine. Combined with arsenic contamination concerns, individuals with thyroid conditions should consult healthcare providers before considering hijiki consumption.

### Does hijiki contain iodine, and is it safe for people monitoring iodine intake?

Yes, hijiki is naturally high in iodine, which can be problematic for people with iodine sensitivity or those following low-iodine diets for thyroid conditions. A single serving of hijiki can exceed the recommended daily iodine intake, making it unsuitable for individuals requiring strict iodine restriction. Those concerned about iodine levels should consult their healthcare provider before consuming hijiki supplements regularly.

### What is the bioavailable form of hijiki for supplement purposes—extract, powder, or whole seaweed?

Hijiki supplements are available as whole-seaweed powder, standardized extracts, and polysaccharide isolates, each with different bioavailability profiles. Standardized extracts concentrating bioactive compounds like phlorotannins and fucoidan may offer higher bioavailability than whole powder, though research directly comparing forms is limited. The choice depends on the intended health target—whole powder retains all nutrients, while extracts optimize specific compounds like fuhalol-type phlorotannins for anti-inflammatory activity.

### Does hijiki interact with anticoagulant or antiplatelet medications?

Hijiki contains fucans and other polysaccharides with potential anticoagulant properties, which could theoretically interact with blood-thinning medications like warfarin or aspirin. While clinical interaction studies are limited, individuals taking anticoagulants should inform their healthcare provider before supplementing with hijiki. Monitoring blood-clotting parameters may be prudent when combining hijiki with antiplatelet or anticoagulant therapies.

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