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

Mechanisms of Action

Fucoxanthin potentially has an anti-obesity effect by influencing 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

Health Benefits

1) Fucoxanthin May Help With Weight Loss

In a study (DB-RCT) 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 [2].

In mice on high-fat diets, fucoxanthin increased weight loss [3].

In diabetic, obese mice, fish oil increased the weight loss effect of fucoxanthin [4].

2) Fucoxanthin May Potentially 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 [5].

3) Fucoxanthin May Be Anti-Malarial

In multiple studies, fucoxanthin combated parasites that cause malaria [6, 7].

4) Fucoxanthin May Potentially Fight Aging

In mice treated with ultraviolet radiation, fucoxanthin applied to the skin blocked the premature aging of skin [8].

In skin cells, fucoxanthin protected against sunburn caused by ultraviolet radiation [9].

5) Fucoxanthin May Protect the Brain

In mice with traumatic brain injury, fucoxanthin reduced brain cell death [10].

Fucoxanthin reduced cognitive impairments in mice given brain damage to be similar to Alzheimer’s disease [11, 12].

6) Fucoxanthin May Reduce Inflammation

In two studies on mice and rats, fucoxanthin reduced inflammation related to insulin resistance and eye inflammation [13, 14].

This effect was also seen in cell studies [15].

7) Fucoxanthin 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 [3].

8) Fucoxanthin May Reduce Cholesterol and Triglycerides

In multiple studies of rats on a high-fat diet, fucoxanthin decreased total cholesterol and triglycerides [16, 17].

9) Fucoxanthin May Protect Against Oxidative Stress

In cells, fucoxanthin reduced damage caused by oxidative stress [18, 19].

In cells, fucoxanthin increased glutathione, an antioxidant, after its depletion from UVB radiation [20].

10) Fucoxanthin May Potentially Have Anti-Cancer Effects

In cells, fucoxanthin blocks cancer growth [21, 22, 23].

Intriguingly, it targets cancer cells while leaving other cells functioning normally [24, 25].

In cells, fucoxanthin improved the effectiveness of the chemotherapeutic drug cisplatin [26].

11) Fucoxanthin Combats 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 [27].

12) Fucoxanthin May Potentially Benefit the Heart

Fucoxanthin and other carotenoids may protect the heart because it reduces many of the risk factors related to heart disease, such as inflammation, cholesterol, obesity, and diabetes [28, 1].  

Side Effects

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 [29, 30].

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.

Drugs Interactions

Fucoxanthin inhibits the enzyme CYP3A4. CYP3A4 is responsible for the metabolism approximately 45–60% of prescribed drugs [31, 32, 33, 34, 35].

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 actual dose of the active form in the blood, which often causes unfavorable and long-lasting effects [36].

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 [37].

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

Natural Sources

Natural sources of fucoxanthin include [43, 44, 45]:

  • Seaweed
  • Microalgae
  • Brown algae
  • Kelp


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 [2].

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.

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About the Author

Caroline Lam - MS (MOLECULAR BIOLOGY) - Writer at Selfhacked

Caroline Lam, MS (Molecular Biology)


Caroline received her MS from California State University, Fullerton.

Caroline is passionate about getting rid of the barriers to scientific knowledge and spreading scientific knowledge to everyone. She is fascinated by the effect of the gut on the body and believes in trying different methods for healing, such as pre and probiotics, fixing nutritional deficiencies, and yoga and meditation to reduce stress.

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