Evidence Based

Fucoxanthin (Brown Seaweed Extract) Benefits + Side Effects

Written by Joe Cohen, BS | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Joe Cohen, BS | Last updated:

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Fucoxanthin is a compound (carotenoid) found in brown seaweed. It is known for its potential to combat a variety of health issues including obesity, diabetes, and inflammation. Read ahead to discover the benefits and side effects of fucoxanthin.

What Is Fucoxanthin?

Fucoxanthin is a carotenoid (a compound found in plants responsible for yellow, orange, or red color). The structure of fucoxanthin makes it different from other plant carotenoids (it has an unusual allenic bond, a 5,6-monoepoxide, and 9 conjugated double bonds).

Though its structure makes fucoxanthin unique, it also contributes to its instability, which makes it difficult to study. However, this same instability is exactly what gives it the 1potential to help with health issues such as obesity, diabetes, inflammation, and cancer [1].

How It Works

Fucoxanthin’s anti-obesity effects are thought to be mediated through its ability to influence gene expression of the following genes related to fat metabolism (in rats) [1]:

  • Acetyl-CoA carboxylase (ACC)
  • Fatty acid synthase (FAS)
  • Glucose-6-phosphate dehydrogenase (G6PDH)
  • Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA)
  • Acyl-CoA cholesterol acyltransferase (ACAT)
  • SREBP-1c

Natural Sources

Natural sources of fucoxanthin include [2, 3, 4]:

  • Seaweed
  • Microalgae
  • Brown algae
  • Kelp

Fucoxanthin Health Benefits

1) May Help With Weight Loss

In a study of 151 obese, non-diabetic women with non-alcoholic fatty liver disease, fucoxanthin (0.8 mg to 4.0 mg) and pomegranate seed oil increased weight loss and reduced body and liver fat [5].

In mice on high-fat diets, fucoxanthin increased weight loss [6].

In diabetic, obese mice, fish oil increased the weight loss effect of fucoxanthin [7].

2) May Help With Depression

In a study (questionnaire) of 1745 pregnant women in Japan, increased consumption of seaweed (which contains fucoxanthin) was associated with a decrease in depression during pregnancy [8].

3) May Be Anti-Malarial

In multiple studies, fucoxanthin combated parasites that cause malaria [9, 10].

4) May Fight Aging

In mice treated with ultraviolet radiation, fucoxanthin applied to the skin blocked the premature aging of skin [11].

In skin cells, fucoxanthin protected against sunburn caused by ultraviolet radiation [12].

5) May Protect the Brain

In mice with traumatic brain injury, fucoxanthin reduced brain cell death [13].

Fucoxanthin reduced cognitive impairments in mice given brain damage to be similar to Alzheimer’s disease [14, 15].

6) May Reduce Inflammation

In two studies on mice and rats, fucoxanthin reduced inflammation related to insulin resistance and eye inflammation [16, 17].

This effect was also seen in cell studies [18].

7) May Have Anti-Diabetic Effects

In a study on mice on high-fat diets, fucoxanthin reduced insulin resistance, which is a large factor in diabetes [6].

8) May Reduce Cholesterol and Triglycerides

In multiple studies of rats on a high-fat diet, fucoxanthin decreased total cholesterol and triglycerides [19, 20].

9) May Protect Against Oxidative Stress

In cells, fucoxanthin reduced damage caused by oxidative stress [21, 22].

In cells, fucoxanthin increased glutathione, an antioxidant, after its depletion from UVB radiation [23].

10) May Have Anti-Cancer Effects

In cells, fucoxanthin blocks cancer growth [24, 25, 26].

Intriguingly, it targets cancer cells while leaving other cells functioning normally [27, 28].

In cells, fucoxanthin improved the effectiveness of the chemotherapeutic drug cisplatin [29].

11) May Combat Bone Disease

In cells, fucoxanthin blocked the development of osteoclasts, a type of cell that helps break down bone to restore calcium to the blood. It also had anti-osteoporosis effects in mice with their ovaries removed [30].

12) May Benefit the Heart

Fucoxanthin and other carotenoids may protect the heart because it reduces many of the risk factors related to heart diseases, such as inflammation, cholesterol, obesity, and diabetes [31, 1].

Limitations and Caveats

A limitation to fucoxanthin research is the lack of human trials, as almost all of the studies mentioned were conducted on animal models.

Side Effects & Precautions

Although fucoxanthin has no proven side effects in humans (possibly due to the limited number of human trials), in mice, it increased cholesterol levels. However, it didn’t have negative effects on the kidney, liver, spleen, and gonads or cause any cellular mutations in the mice [32, 33].

Drugs Interactions

Fucoxanthin inhibits the enzyme CYP3A4. CYP3A4 is responsible for the metabolism approximately 45–60% of prescribed drugs [34, 35, 36, 37, 38].

Inhibiting the activity of CYP3A4 can have two different effects on drug metabolism.

It can decrease the inactivation or degradation of the drug, and thus, increase the amount of the active form in the blood, which often causes unfavorable and long-lasting effects [39].

Or, it can decrease the activation of medications that are administered as a pro-drug, and thus, decrease the actual dose of the active form of the drug that reaches the blood, which lowers the biological efficacy of the drug [40].

The following drugs are likely affected by fucoxanthin and thus, consumption should be discussed with your doctor if you take these medications:

  • Opioids: sufentanil [37] and methadone [38]
  • Immunosuppressants: cyclosporine [39], tacrolimus [41], and sirolimus [42]
  • Antihypertensive drugs: felodipine [39] and nifedipine [43]
  • Anticancer drugs: endoxifen [43], tamoxifen [44], and sunitinib [43]
  • Sedatives: midazolam [43]
  • Cholesterol-lowering drugs (statins): simvastatin [45], atorvastatin, and lovastatin [43]
  • Antibiotics: erythromycin [41]
  • Corticosteroids: fluticasone propionate [43]


The only human trial mentioned used a dosage of 0.8 – 4.0 mg fucoxanthin combined with pomegranate seed oil, which caused no adverse effects [5].

User Experiences

Users say fucoxanthin patches work well to increase weight loss and increase energy. However, some users believe the patches don’t work fast enough and don’t help with decreasing appetite.

Many users taking fucoxanthin pills believe they work well in reducing weight without needing to physically exercise.

Buy Fucoxanthin

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About the Author

Joe Cohen, BS

Joe Cohen, BS

Joe Cohen won the genetic lottery of bad genes. As a kid, he suffered from inflammation, brain fog, fatigue, digestive problems, anxiety, depression, and other issues that were poorly understood in both conventional and alternative medicine.Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers.Joe is a thriving entrepreneur, author and speaker. He is the CEO of SelfHacked, SelfDecode and LabTestAnalyzer.His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.
Joe has been studying health sciences for 17 years and has read over 30,000 PubMed articles. He's given consultations to over 1000 people who have sought his health advice. After completing the pre-med requirements at university, he founded SelfHacked because he wanted to make a big impact in improving global health. He's written hundreds of science posts, multiple books on improving health, and speaks at various health conferences. He's keen on building a brain-trust of top scientists who will improve the level of accuracy of health content on the web. He's also founded SelfDecode and LabTestAnalyzer, popular genetic and lab software tools to improve health.

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