Cystoseira canariensis

BotanicalSeaweedBest with a meal

What is it

Cystoseira canariensis is a brown alga native to the Canary Islands, marketed under brand names like Phenalgin in sports supplements. It is claimed to inhibit myostatin to enhance muscle growth.

Evidence for 1 use

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

Muscle growth (myostatin inhibition claim)

Mixed Evidence

Human studies have not confirmed claims of muscle growth or strength benefit from Cystoseira canariensis. Marketing claims significantly outpace the available evidence.

How it works

Marketing claims center on the idea that polysaccharides from Cystoseira canariensis bind and neutralize myostatin, a protein that normally limits muscle growth. This theory is based on early laboratory studies. Human clinical trials of Cystoseira canariensis as a myostatin inhibitor have not consistently shown muscle growth benefits. The original commercial claims have outpaced rigorous evidence in humans.

Dosage

Supplement products typically use 500-1500 mg of Cystoseira canariensis extract daily, often divided into doses around training.

When and how to take it

WHEN: Pre-workout or with meals for athletic use. HOW: With water and food.

1 commercial form

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

Cystoseira canariensis extract (Phenalgin)

Branded extract used in muscle-building supplements.

Large polysaccharides with uncertain oral absorption.

Safety

Generally tolerated. Common side effects are GI upset and iodine-related effects from the seaweed source. Long-term safety data are limited.

Who should be cautious

Caution with thyroid disorders, bleeding disorders, and pregnancy/breastfeeding. Verify product testing for heavy metals.

Interactions

Iodine content may interact with thyroid medications. Possible mild antiplatelet activity.

Frequently asked questions

Does Cystoseira canariensis really block myostatin?⌄

Early laboratory studies suggested possible binding, but human trials have not shown meaningful effects on muscle mass or strength. Evidence is weak.

References

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

Research on Cystoseira canariensis (PubMed search) — PubMed link

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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.