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Limited evidenceHeart & metabolic

Chlorella

Small, unimpressive lipid effects — around 7 mg/dL off LDL in trials of mixed quality — and nothing controlled supporting the detox, immunity, or energy claims it's mostly sold on. Treat it as a nutrient-dense green food, not a therapy.

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What the science says

  • Total and LDL cholesterol Limited evidence

    A dose-response meta-analysis of 10 RCTs in 539 adults found total cholesterol -7.47 mg/dL (95% CI -12.98 to -1.96) and LDL -7.71 mg/dL (95% CI -14.05 to -1.37), with no significant change in triglycerides or HDL. Only 4 of the 10 trials were at low risk of bias, and only 2 verified the content, purity, or contamination of the chlorella used. The LDL benefit appeared only up to about 1,500 mg/day and vanished at higher doses.

  • Broader cardiovascular risk factors Limited evidence

    An earlier meta-analysis of RCTs reported reductions in total cholesterol, LDL, and blood pressure with chlorella, but the pooled results were driven by small, short trials in a narrow set of populations. Effect sizes are within the range attributable to dietary co-interventions and unblinded design.

  • Heavy metal detoxification Limited evidence

    The detox claim rests on rodent studies of mercury and dioxin binding, plus one small human trial in an occupationally exposed group. There is no controlled human evidence that chlorella meaningfully increases excretion of mercury, lead, or other metals in ordinary users.

Dosage & safety

Studied dose1,500-8,000 mg/day, most commonly 5 g/day, for 4-16 weeks in trials. Notably, the dose-response analysis found the lipid benefit only at doses at or below 1,500 mg/day, so higher intakes are not supported.
SafetyGI upset, flatulence, and green stool are common. Chlorella is very high in vitamin K and interacts with warfarin. Case reports document chlorella-induced hypersensitivity pneumonitis and photodermatitis (photosensitivity from pheophorbide). Cell-wall-cracked products from unregulated sources have shown heavy-metal contamination — the same problem the supplement is supposed to solve. Some products add iodine; check labels if you have thyroid disease or an iodine-restricted diet.

How to take it

TimingTiming does not matter.
With food?Take it with food; flatulence and green stool are common in the first week.
Worth knowingCracked-cell-wall product is more digestible, but sourcing matters more - heavy-metal contamination has been found in exactly the products sold as detox aids.

Interactions

With medications

  • warfarin

    Chlorella is very high in vitamin K and directly opposes warfarin. avoid it, or keep your intake rigidly constant with INR monitoring

  • levothyroxine and antithyroid drugs

    Some chlorella products add iodine, which can destabilise thyroid treatment. check the label for iodine and tell your prescriber if it contains any

With other supplements

  • kelp, sea moss and other iodine-containing supplements

    Iodine loads add up and excess iodine can cause both hypo- and hyperthyroidism. do not stack iodine sources

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does chlorella lower cholesterol?

Only slightly, with limited evidence: a meta-analysis of 10 trials found chlorella lowered LDL by about 7.71 mg/dL, and the benefit appeared only up to about 1,500 mg/day. Only 4 of those trials were at low risk of bias.

Does chlorella detox heavy metals?

There is no controlled human evidence that chlorella meaningfully increases excretion of mercury, lead or other metals in ordinary users; the claim rests on rodent studies. Ironically, some chlorella products have themselves shown heavy-metal contamination.

Does chlorella interact with warfarin?

Yes: chlorella is very high in vitamin K and directly opposes warfarin. Avoid chlorella if you take warfarin, or keep your intake rigidly constant with INR monitoring.

What are the side effects of chlorella?

Chlorella commonly causes stomach upset, flatulence and green stool, and case reports describe hypersensitivity pneumonitis and photosensitivity. Some chlorella products add iodine, so check the label if you have thyroid disease or take thyroid medication.

Scientific references

Where to buy

Earth Circle Organics, 100% Organic Chlorella Tablets, 400 Tablets

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