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Chlorella: What It Is, What the Research Shows and Side Effects
Chlorella is a single-celled green alga sold as tablets and powder. Small trials suggest modest effects on cholesterol and blood pressure; it can upset the stomach and weaken warfarin.
Last updated 3 November 2026
Chlorella: the short answer
Chlorella is a single-celled freshwater green alga sold as tablets and powder, about half protein and rich in chlorophyll, iron and vitamin K. In a 2018 analysis of 19 small trials with 797 people, it lowered total cholesterol by about 9 mg/dL and slightly lowered blood pressure and fasting blood sugar, mostly in people with high cholesterol or blood pressure, but a 2025 analysis found no clear effect on blood pressure or blood fats. There is no good evidence that it removes heavy metals or other toxins in people. It often causes stomach upset and green stools at first, can make the skin sensitive to sunlight, and its vitamin K can weaken warfarin.
| What it is | A single-celled freshwater green alga (Chlorella vulgaris or C. pyrenoidosa), sold as tablets and powder; about half protein, with chlorophyll, iron and vitamin K. |
|---|---|
| Research | A 2018 analysis of 19 small trials (797 people) found total cholesterol about 9 mg/dL lower and small falls in blood pressure; a 2025 analysis found no clear effect. |
| Detox claims | Based mainly on animal and laboratory studies; no good evidence that it removes heavy metals in people. |
| Dose | No established dose; trials mostly used a few grams a day. |
| Safety | Stomach upset and green stools at first; sun sensitivity; allergic reactions; vitamin K can weaken warfarin; may contain iodine. |
| In products we review | JointVive, NeuroPrime, Pineal Guardian X |
Sources: Effect of Chlorella supplementation on cardiovascular risk factors: meta-analysis of randomized controlled trials (Clin Nutr 2018) · Chlorella and spirulina as adjuvants of cardiovascular risk factor control: systematic review and meta-analysis (Nutrients 2025) · Chlorella: uses, side effects and interactions (RxList)
Benefits of Chlorella
What is chlorella?
Chlorella is a single-celled green alga that grows in fresh water. Supplements, usually Chlorella vulgaris or Chlorella pyrenoidosa, are grown in tanks, dried and sold as tablets or powder, often labelled “broken cell wall” because the alga’s tough outer wall is cracked to make it easier to digest. Dried chlorella is about half protein and contains chlorophyll, which makes it deep green, along with iron, carotenoids and vitamin K.
Why people take it
Chlorella is sold as a “superfood” and for detox, especially to remove heavy metals, and also for cholesterol, blood pressure, blood sugar, immunity and energy. It is often sold together with spirulina, another algae powder.
Top Rated Supplements with Chlorella
Products we review that list Chlorella as an ingredient. Not every product discloses how much of each ingredient a serving contains, so check each review before assuming it matches the amounts used in studies.
JointVive is a liquid supplement from Nutraville sold for joint comfort, flexibility and mobility, taken as “one drop per day” from a 60 ml dropper bottle. It names nine ingredients: pine bark extract, tamarind, chlorella, ginkgo biloba, spirulina, lion’s mane mushroom, bacopa, moringa and neem, with no amounts. This review covers what is known about each, why only two of them have any joint research, the real prices and how the 365-day refund works.
NeuroPrime is a liquid memory supplement in a 60 mL dropper bottle, with bacopa, lion’s mane, ginkgo, pine bark and five other ingredients. This review covers what is in it, why the dose is unclear, which ingredients have trials, the references we checked, and how its 365-day guarantee compares with its return policy.
Pineal Guardian X is a liquid memory supplement sold through ClickBank on a story that fluoride hardens the pineal gland and causes memory loss. Its nine ingredients are the same as NeuroPrime’s, from the same company. This review checks the claims, the prices and the refund rules.
Scientific Analysis of Chlorella
What the research shows
- Cholesterol and blood pressure: a 2018 analysis of 19 small trials with 797 people found that chlorella lowered total cholesterol by about 9 mg/dL and slightly lowered LDL cholesterol, blood pressure and fasting blood sugar, mainly in people with high cholesterol or high blood pressure, and more with over 4 g a day taken for at least 8 weeks. A 2025 analysis found no clear effect on blood pressure or blood fats, so the evidence is weak and mixed.
- Detox and heavy metals: claims that chlorella removes mercury, lead or other “toxins” come mainly from animal and laboratory studies; there is no good evidence that it does this in people.
- Immunity: small trials found changes in immune markers in blood tests, which do not show that people get ill less often.
Chlorella vs spirulina
Chlorella is a true green alga with a tough cell wall that has to be broken before it can be digested; spirulina is a blue-green cyanobacterium with a soft wall. Both are protein-rich powders, and spirulina has modest evidence for cholesterol and blood pressure. Neither replaces vegetables or medicine.
Vitamin B12 in chlorella
Some chlorella products contain vitamin B12, but the amount varies widely between products, and algae can also contain inactive forms that do not count. Vegans should not rely on chlorella for B12 and should use fortified foods or a vitamin B12 supplement instead.
Side effects and safety
- Stomach: diarrhoea, nausea, gas, stomach cramps and green stools are common in the first weeks.
- Warfarin: chlorella contains vitamin K, which works against warfarin, and the amount varies between products; a case report describes warfarin no longer working properly after a patient started chlorella. Ask your doctor first and have your blood checked.
- Sunlight and allergy: it can make the skin more sensitive to sunlight, and allergic reactions, including asthma, have been reported.
- Iodine: chlorella can contain iodine, which matters for people with thyroid disease.
- Immune system: it may stimulate the immune system, so people taking medicines that suppress it, such as after a transplant, should avoid it unless their doctor agrees.
- Purity and long-term use: algae supplements, mainly blue-green algae harvested from lakes, have been found contaminated with liver toxins (microcystins) and heavy metals, so choose a product tested by an independent lab. There is little safety data for pregnancy, breastfeeding or use beyond two months.
Products we review that contain it
JointVive includes chlorella with spirulina for joints, although neither has been studied for joint pain. NeuroPrime and Pineal Guardian X, which share the same nine ingredients, include it for memory; there are no memory trials of chlorella in people. None of the three labels gives the amount. Anyone taking warfarin should check with their doctor before using any of them.
Frequently Asked Questions
A single-celled freshwater green alga, dried and sold as tablets and powder. It is about half protein and contains chlorophyll, iron and vitamin K.
Small trials suggest it may lower cholesterol and blood pressure slightly in people with high levels, but a 2025 analysis found no clear effect, so the evidence is weak. Claims for detox, immunity and energy are not backed by good human trials.
There is no good evidence that it does in people. The claims come mainly from animal and laboratory studies.
Chlorella is a green alga with a tough cell wall that has to be broken before it can be digested; spirulina is a blue-green cyanobacterium with a soft wall. Both are protein-rich powders with limited evidence for cholesterol and blood pressure.
Diarrhoea, nausea, gas, cramps and green stools are common at first. It can also make the skin sensitive to sunlight, cause allergic reactions and, because of its vitamin K, weaken warfarin.
Only with your doctor’s agreement and blood checks: chlorella contains vitamin K, which works against warfarin, and the amount varies between products.
Some products do, but the amount varies and algae can contain inactive forms, so vegans should use fortified foods or a vitamin B12 supplement instead.
There is no established dose. Trials have mostly used a few grams a day, and in the 2018 analysis the effects were larger with more than 4 g a day for at least 8 weeks.
Among the products we review, JointVive, NeuroPrime and Pineal Guardian X. None of the three labels gives the amount.
⚖️ Conclusion
Chlorella is a nutritious algae powder, but the case for taking it is weak: small trials found modest falls in cholesterol and blood pressure that a 2025 analysis could not confirm, and the detox claims rest on animal studies. It commonly upsets the stomach at first, and anyone taking warfarin or immune-suppressing medicines, or with thyroid disease, should check with a doctor first. In the products we review, chlorella is one of many ingredients with no amount stated, so it is unlikely to make a difference.