Evigrade

Chlorella

Freshwater unicellular green alga (Chlorella vulgaris / pyrenoidosa), supplement, marketed for «mercury detox»

ATC code: A11JA-CHLORELLA

Brand names – supplements: Sun Chlorella A, NOW Chlorella, BioPure Yaeyama Chlorella, Doctor's Best ChlorellaSupplements are not tested in clinical trials and are not registered as medications.

Updated · Methodology

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

D

Superfoods and adaptogens (marketing category)

Not recommended

Chlorella is a freshwater microalga sold as a powder or tablets and marketed as a superfood and adaptogen, with promises of detox, more energy and immune support. There is no convincing evidence that the supplement delivers these effects in healthy people. It also shows no harm at usual doses, but there is little reason to expect the claimed benefits. For genuine support, sleep, a diet with vegetables and greens, and regular physical activity do far more.

F

Body detoxification and cleansing

Not recommended

Chlorella is actively marketed for «removing mercury from amalgam fillings», «lead detox» and «binding gut toxins». These claims do not withstand scrutiny. The Merritt systematic review (J Med Toxicol 2022) analysed available clinical data on chlorella as a heavy-metal chelator: there are no quality RCTs, epidemiologic studies are small and contradictory, and no data show that chlorella reduces blood or urine mercury in patients after amalgam removal. The American Dental Association and (2020) confirm that amalgam fillings are safe in adults and pregnant women outside risk groups, and no special detox is needed after them. The «heavy-metal removal» concept with chlorella is part of «biological dentistry» (IAOMT), not supported by evidence-based medicine. Real heavy-metal poisoning is treated with registered chelators – dimercaprol, DMSA, EDTA – under toxicology supervision. If chlorella was bought for «post-amalgam detox», discuss with a doctor; the risk of unnecessary intervention outweighs the benefit.

How to read tiers A–F
  • AStrong evidence – first or second line in international guidelines
  • BRecommended in selected cases
  • CStudy data contradict each other
  • DBenefit not proven, no documented harm
  • FDocumented harm, or risk without benefit

Mechanism of action

Chlorella is a unicellular freshwater green alga with a tough cell wall that must be cracked mechanically for bioavailability (cracked-cell wall). It contains chlorophyll (1.5–2%), Chlorella Growth Factor (CGF), protein, vitamin B12 analogues (biologically inactive in humans), carotenoids and minerals. Manufacturers claim that the dense cell wall binds heavy metals in the gut, but in vivo binding in humans is documented only for methylmercury from fish in small epidemiologic studies, not for mercury from amalgam fillings nor for lead, arsenic or cadmium. has not approved a single chlorella health claim. AESAN classifies it as a complemento alimenticio without therapeutic indication.

Safety

Contraindications

  • Autoimmune disease (rheumatoid arthritis, SLE, multiple sclerosis) – theoretical immune activation
  • Warfarin therapy (chlorella contains vitamin K and reduces anticoagulation)
  • Severe hepatic or renal impairment
  • Known algae allergy

Serious adverse effects

  • Severe allergic reactions in algae-sensitised users
  • Reduced warfarin efficacy with thrombosis risk

Common adverse effects

  • Gastrointestinal discomfort, nausea, flatulence in the first days
  • Green stool discolouration
  • Photodermatitis with prolonged use (chlorophyll increases photosensitivity)

Pregnancy: can you take Chlorella?

Chlorella safety in human pregnancy has not been studied in RCTs. Main risks are heavy-metal, arsenic and mycotoxin contamination when grown in uncontrolled open ponds. EFSA has set no safe dose for pregnant women. AEMPS and AESAN advise against supplements without therapeutic indication during pregnancy.

Breastfeeding: can you take Chlorella?

Lactation safety has not been studied in RCTs. Contaminants from low-quality chlorella can pass into human milk. Chlorella is not justified during lactation.

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

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Frequently asked

What is Chlorella used for?

Chlorella is evaluated for the following indications with varying evidence strength: Superfoods and adaptogens (marketing category) (evidence tier D), Body detoxification and cleansing (evidence tier F). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Chlorella?

Common side effects of Chlorella (≥ 1 in 100): Gastrointestinal discomfort, nausea, flatulence in the first days, Green stool discolouration, Photodermatitis with prolonged use (chlorophyll increases photosensitivity). See the Safety section for uncommon and serious reactions.

Is Chlorella safe during pregnancy?

Chlorella safety in human pregnancy has not been studied in RCTs. Main risks are heavy-metal, arsenic and mycotoxin contamination when grown in uncontrolled open ponds. EFSA has set no safe dose for pregnant women. AEMPS and AESAN advise against supplements without therapeutic indication during pregnancy.

Is Chlorella compatible with breastfeeding?

Lactation safety has not been studied in RCTs. Contaminants from low-quality chlorella can pass into human milk. Chlorella is not justified during lactation.

Who should not take Chlorella?

Chlorella is contraindicated in: Autoimmune disease (rheumatoid arthritis, SLE, multiple sclerosis) – theoretical immune activation; Warfarin therapy (chlorella contains vitamin K and reduces anticoagulation); Severe hepatic or renal impairment; Known algae allergy. Full list in the Safety section.

Other drugs in this group

Cholecalciferol, Choline (umbrella: bitartrate, phosphatidylcholine, lecithin), Cordyceps (Cordyceps sinensis, Cordyceps militaris), Cranberry (Vaccinium macrocarpon), Indole-3-carbinol (I3C), Omega-9 monounsaturated fatty acid (oleic acid), Royal jelly, Vitex agnus-castus (chasteberry, monk's pepper)