Fucoxanthin: Nutrients, What Research Shows and Safety
Fucoxanthin is an orange pigment of brown seaweeds sold for weight loss. See the human trials, absorption, safety data and the iodine and metal cautions.
Content last updated . This page has not been medically reviewed.
Fucoxanthin is a carotenoid, an orange-brown pigment, found in brown seaweeds such as wakame, kombu and hijiki, and in diatoms (tiny algae). [2] Supplements are sold for weight loss and "metabolism". This page separates the pigment in food from extracts and capsules, and says plainly that most of the evidence is from animals and cells.
Read this first
- Weight-loss claims are not proven in people. The strongest-looking human result we found used a mix of fucoxanthin and pomegranate seed oil, so it cannot be credited to fucoxanthin alone. [3] A trial of fucoxanthin alone found no change in visceral fat. [1] A trial of a diatom extract found no added weight loss. [4]
- Brown-seaweed products can carry a lot of iodine. Iodine in tested seaweeds ranged from 16 mcg per gram in nori to over 8,000 mcg per gram in processed kelp granules. [8] The American Thyroid Association advises against kelp or iodine supplements above 500 mcg of iodine a day. [10] We found no iodine data for fucoxanthin products, so check the label and any test report.
- Metals vary by product. A case report tied a kelp supplement to high arsenic, and 8 of 9 kelp supplements tested exceeded a US reference level. [9] We found no data on fucoxanthin products specifically.
- Long-term human safety is unknown. Animal studies and one 8-week human trial found no serious problems. [1] [2]
- Allergic reaction signs (trouble breathing, swelling of the face or throat): call 911 or your local emergency number.
What is in it
No USDA entry for this food. Fucoxanthin is a compound, not a food, so there is no standard nutrient table.| Item | What the source reports | Form |
|---|---|---|
| Fucoxanthin in wakame | Five people eating stir-fried wakame took in 6.1 mg of fucoxanthin a day for a week. [2] | Whole seaweed, as a daily intake |
| Fucoxanthin in 15 brown algae | The authors of a trial say akamoku had the highest content of the 15 species they reviewed. [1] No values given. | Seaweed |
| Capsule used in a trial | Akamoku oil with 1% fucoxanthin; 1 or 2 mg of fucoxanthin a day. [1] | Capsule |
| Combination product | 2.4 mg fucoxanthin with 300 mg pomegranate seed oil in the 600 mg version. [3] | Capsule mix |
We did not read a per-100 g fucoxanthin value for wakame or kombu: Proper evidence not found in the sources we read. Content varies with species, season and processing.
What research says
| Health goal | What the sources found | Strength of evidence | What was studied |
|---|---|---|---|
| Weight and body fat | 16 weeks, 151 obese women: the combination product was reported to lower weight (about 5 kg), body fat and liver fat. [3] 8 weeks, 60 adults: 1 or 2 mg of fucoxanthin alone did not change visceral fat, weight or BMI. [1] 12 weeks, 37 women: 4.4 mg from a diatom extract added no weight or fat loss. [4] | Mixed | Combination product; akamoku oil; diatom extract |
| Blood sugar | HbA1c fell 0.14% on 2 mg a day versus a rise of 0.06% on placebo. It came from a small exploratory analysis. [1] | Insufficient evidence | Akamoku oil capsule, 60 adults |
| Liver fat and liver enzymes | Improved in the combination-product trial. [3] | Insufficient evidence (not fucoxanthin alone) | Combination product |
| Antioxidant, anti-inflammatory, cancer | Described in cells and animals. [11] | Lab or animal only | Cells, rodents |
| Reviews | A 2026 review lists fucoxanthin among compounds tested in weight-loss trials, and says enriched extracts often did better than single compounds. [6] Another review says human trials are few and show modest weight loss. [7] | Mixed | Reviews |
Industry funding: the Japanese trial's capsules were bought from a maker and the work had public grants. [1] The Xanthigen trial's funding was not shown in the record we read, and it tested a commercial product. We found no independent repeat. [3] One diatom trial lists a company grant. [4]
Food versus supplement. Eating wakame or kombu gives a small amount of fucoxanthin with fiber and iodine. Extracts and capsules are different products. Trial results for one do not carry to the other.
How much is a normal serving
There is no official serving or intake for fucoxanthin. The trials used 1 to 2 mg a day for 8 weeks [1], 2.4 mg in a combination product for 16 weeks [3], and 4.4 mg from a diatom extract for 12 weeks [4]. A small human study counted 6.1 mg a day from about 6 g of dried wakame. [2] These are study figures, not advice.Absorption: fucoxanthin is changed in the gut to fucoxanthinol, which is then taken up. [1] [2] In five volunteers eating wakame, blood fucoxanthinol was low, and the authors suggest seaweed fiber may block absorption. A review says taking it with oil could increase absorption, from animal and combination-product work. [2] In the Japanese trial, blood fucoxanthinol rose with dose. [1]
Safety, allergy and medicines
- Animal safety. In rats, more than 2,000 mg per kg of body weight caused no deaths, and a 13-week no-effect level was 200 mg per kg. Some high animal doses raised blood cholesterol. [2]
- Human safety. At 1 and 2 mg a day for 8 weeks, the Japanese trial saw no adverse effects. [1] No long-term safety study found.
- Diatom extract. EFSA could not conclude a diatom (Phaeodactylum) extract was safe: a 90-day animal study found effects at the lowest dose, the composition was incomplete, and there were possible light-sensitizing compounds. [5] That is a different source from brown seaweed.
- Iodine and thyroid. Kelp-type seaweed can supply very large amounts. The adult upper level is 1,100 mcg a day. [8] [10] People with thyroid disease, pregnant and breastfeeding women, infants and older adults are more at risk from too much iodine. [10] See iodine and kelp and seaweed supplements.
- Metals. [9] See heavy metals and contaminants in foods.
- Medicines, pregnancy, children. Proper evidence not found in the sources we read. Ask a clinician or pharmacist.
Choosing, storing and food safety
- Check whether a product is purified fucoxanthin or crude brown seaweed, and look for iodine and metals on a test report.
- We did not read an EU, US or Canadian regulatory status for fucoxanthin itself.
- Do not use it to replace medical weight care.
Related pages
Health connections for Fucoxanthin
What research links to eating or drinking this food, and how strong the evidence is. Many studies are observational or use juice, powder, oil or extracts rather than the food as eaten; each card says which.
Fucoxanthin and weight loss: what trials found
Preliminary or mixedClaims of weight loss rest mostly on rodent studies. The one positive human trial we read used a mixture with pomegranate seed oil. A trial of fucoxanthin alone (1 or 2 mg a day for 8 weeks) found no change in visceral fat, and a diatom-fucoxanthin trial found no added weight loss.
Supplements: Weak and mixed; small trials, some with commercial ties.
Xanthigen (fucoxanthin plus pomegranate oil) trial
Preliminary or mixedA 16-week trial in 151 obese women reported weight and liver-fat loss with a combination product containing 2.4 mg fucoxanthin. The effect cannot be assigned to fucoxanthin alone, and we found no independent repeat.
Supplements: Single trial of a combination product.
Fucoxanthin, HbA1c and liver fat: lab versus people
Lab or animal research onlyAn 8-week trial saw a small HbA1c drop at 2 mg a day (exploratory, mostly in a few genotype carriers). Other claims are lab or animal findings.
Supplements: Do not rely on it for blood sugar.
Absorption of fucoxanthin and effect of dietary fat
Lab or animal research onlyIn animals and cells fucoxanthin is turned into fucoxanthinol in the gut. In five people eating wakame, blood fucoxanthinol was low. Reviews say oil may raise absorption.
Supplements: Human absorption data are small.
Fucoxanthin in wakame and kombu
Not enough evidenceWe did not read a per-100 g fucoxanthin value for wakame or kombu. A trial authors reported that among 15 brown algae, akamoku had the highest content.
Supplements: Proper evidence not found for typical serving content.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (1)
- Weight ManagementPreliminary or mixed
Marketed for weight loss, but results are mixed: one combination-product trial was positive, and trials of fucoxanthin alone found no change in visceral fat or no added loss. Most support is from animals.
Body systems (1)
- Metabolism & WeightPreliminary or mixed
Same mixed human findings; most evidence is from rodents.
Body parts (1)
- ThyroidDocumented risk
Brown seaweed can carry very high iodine, which can affect the thyroid. No iodine data were found for purified fucoxanthin, so check any seaweed-based product.
Functional actions (2)
- Anti-InflammatoryLab or animal research only
Lab and animal findings only.
- AntioxidantLab or animal research only
Described in lab and animal studies; no human outcome shown.
Root causes (1)
- Heavy Metal ExposureDocumented risk
Kelp supplements have shown high arsenic. No data for fucoxanthin products specifically.
Documented risks and interactions (4)
- Safety data on fucoxanthin. In rats no deaths at doses above 2000 mg/kg and a 13-week no-effect level of 200 mg/kg; some high animal doses raised blood cholesterol. A small trial at 1 and 2 mg a day for 8 weeks found no adverse effects. Long-term human safety is unknown.
- Iodine in brown-seaweed extracts and powders. Kelp-type seaweeds can carry very large amounts of iodine. We found no iodine data for fucoxanthin products, so check labels and test reports. The American Thyroid Association advises against kelp or iodine supplements above 500 mcg iodine a day.
- Arsenic and metals in brown-seaweed products. A case report linked a kelp supplement with high arsenic; 8 of 9 tested kelp supplements exceeded a US reference level. No data for fucoxanthin products specifically.
- Fucoxanthin from diatoms: EFSA opinion. EFSA could not conclude a diatom (Phaeodactylum) extract was safe, citing a 90-day animal effect level, incomplete composition and possible phototoxic compounds.
Frequently asked questions
Does fucoxanthin burn fat?
In rodents it did. In people the results are mixed: a combination product helped in one trial, while fucoxanthin alone and a diatom extract did not change fat. [1] [3] [4]
How much fucoxanthin is in wakame?
We did not find a per-serving value. Five people eating wakame took in 6.1 mg a day in one study. [2]
Is fucoxanthin safe?
Animal studies and one 8-week human trial found no serious problems. Long-term safety is unknown. The bigger concern is iodine and metals in some brown-seaweed products. [1] [2] [8] [9]
Should I take it with fat?
A review says oil may increase absorption, but that comes from animal and combination-product work. [2]
Can people with thyroid disease take it?
Ask a clinician. Kelp-type seaweed products can supply too much iodine. [8] [10]
References
- Mikami N et al. Fucoxanthin-enriched akamoku oil, HbA1c and UCP1: randomised controlled trial. J Nutr Sci. 2017. Read 2026-10-24.
- Peng J et al. Fucoxanthin, a marine carotenoid present in brown seaweeds and diatoms. Mar Drugs. 2011. Read 2026-10-24 (first 100,000 characters).
- Abidov M et al. The effects of Xanthigen in obese premenopausal women. Diabetes Obes Metab. 2010. Read 2026-10-24 (abstract record).
- Dickerson B et al. Phaeodactylum tricornutum extract (Mi136) with weight management in overweight women. Nutrients. 2024. Read 2026-10-24 (abstract record).
- EFSA NDA Panel. Safety of an ethanolic extract of the dried biomass of Phaeodactylum tricornutum as a novel food. EFSA J. 2023. Read 2026-10-24 (abstract record).
- Coulter AA et al. Phytocompounds that target white adipose tissue for weight loss. Obes Rev. 2026. Read 2026-10-24 (abstract record).
- Limijadi EKS et al. Marine-algal-derived postbiotics and the gut-adipose axis in obesity. Nutrients. 2025. Read 2026-10-24 (abstract record).
- Teas J et al. Variability of iodine content in common commercially available edible seaweeds. Thyroid. 2004. Read 2026-10-24 (abstract record).
- Amster E et al. Case report: potential arsenic toxicosis secondary to herbal kelp supplement. Environ Health Perspect. 2007. Read 2026-10-24 (abstract record).
- American Thyroid Association. Statement on the potential risks of excess iodine ingestion and exposure. 2013. Read 2026-10-24 (via search summary).
- Mumu M et al. Fucoxanthin: a promising phytochemical on diverse pharmacological targets. Front Pharmacol. 2022. Read 2026-10-24 (abstract record).