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Chlorella Extract

Also known as: Chlorella, green algae, freshwater microalgae, Chlorella vulgaris

Overview

Chlorella extract is derived from *Chlorella vulgaris*, a unicellular green microalgae found in freshwater environments. It is cultivated globally for dietary supplementation and functional food applications. Chlorella is primarily used as a dietary supplement for its potential effects on liver health, lipid metabolism, and antioxidant activity. It is rich in protein, chlorophyll, vitamins, minerals, and various bioactive compounds. A key characteristic is its rigid cellulose cell wall, which necessitates mechanical processing (e.g., cracking) to enhance human bioavailability and absorption. Research on Chlorella is of moderate maturity, with several randomized controlled trials (RCTs) and systematic reviews available, particularly concerning liver and lipid biomarkers. While evidence is mixed, it is improving, with some high-quality meta-analyses. However, many studies have small sample sizes and heterogeneity in dosing and outcomes, indicating a need for more large-scale, long-term RCTs.

Benefits

Chlorella extract has demonstrated several evidence-based benefits, primarily in specific populations. A meta-analysis of 7 RCTs indicated that *C. vulgaris* supplementation significantly reduced serum aspartate aminotransferase (AST) levels (WMD −9.15 U/L; 95% CI −16.09, −2.21), with a more pronounced effect observed in non-alcoholic fatty liver disease (NAFLD) patients (WMD −16.42 U/L; 95% CI −29.75, −3.09). While no significant overall effect was found for alanine aminotransferase (ALT) or alkaline phosphatase (ALP), a subgroup analysis showed a modest ALT reduction. For lipid profiles, a systematic review and dose-response meta-analysis reported modest but significant reductions in total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in adults, though no effect on triglycerides (TG) or high-density lipoprotein cholesterol (HDL-C) was noted. Preclinical and some human studies also suggest increased antioxidant enzyme activity, but high-quality human RCT data are limited for this effect. The clinical significance of these modest effect sizes, particularly for lipid outcomes, remains uncertain and may not warrant routine supplementation in healthy individuals. Benefits are most notable for NAFLD patients and adults with dyslipidemia, with effects typically observed after 4–12 weeks of supplementation.

How it works

Chlorella's proposed mechanisms of action involve several biological pathways. For liver protection, it is thought to reduce oxidative stress, modulate inflammatory pathways, and enhance hepatic detoxification enzymes. Its lipid-modulating effects may stem from inhibiting cholesterol absorption, influencing lipid metabolism enzymes, and providing antioxidant benefits. The observed antioxidant activity is linked to increases in endogenous antioxidant enzymes like catalase and superoxide dismutase. Chlorella primarily interacts with the liver and cardiovascular system through these metabolic and antioxidant pathways. While exact molecular targets are not fully elucidated, potential targets include hepatic enzymes (AST, ALT) and regulators of lipid metabolism. Bioavailability is a critical factor, as the rigid cellulose cell wall of Chlorella limits absorption; therefore, mechanical processing (e.g., cracking) is essential for adequate absorption, as whole-cell products are poorly absorbed.

Side effects

Chlorella is generally well tolerated in the short term, but comprehensive long-term safety data are currently lacking. The most common side effects, occurring in over 5% of users, are gastrointestinal symptoms such as nausea, vomiting, and abdominal pain, which may be more prevalent with poorly processed products. Uncommon side effects (1–5%) include allergic reactions like rash and respiratory symptoms, particularly in sensitive individuals. While very rare, severe allergic reactions, including anaphylaxis, are possible. There are no well-documented drug interactions, but theoretical risks exist for additive effects with anticoagulants or antihypertensives, though clinical evidence is insufficient to confirm these. Chlorella is contraindicated in individuals with known allergies to algae or seafood, and caution is advised for those with iodine sensitivity. Safety in special populations such as pregnant or lactating women and children has not been established, and allergic potential may be higher in children.

Dosage

The minimum effective dose for Chlorella is not well established, but most randomized controlled trials (RCTs) have utilized doses ranging from 1.5 to 6 grams per day. The optimal dosage range is generally considered to be 2–5 grams per day, typically divided into two doses. While higher doses, up to 10 grams per day, have been used in some studies, they have not consistently demonstrated clear additional benefits. There is no established maximum safe dose; however, doses up to 10 grams per day appear safe in short-term studies, but long-term safety at these levels remains unknown. Chlorella may be taken with meals to help mitigate potential gastrointestinal side effects. For optimal absorption, it is crucial to prefer cracked or broken cell wall products, as mechanical processing is essential to overcome the rigid cellulose cell wall and improve bioavailability. Whole-cell products are poorly absorbed. No specific cofactors are identified as required for Chlorella's efficacy, though synergistic effects with other antioxidants are theoretically possible but unproven.

FAQs

Is chlorella effective for liver health?

Evidence suggests a modest reduction in AST levels, particularly in NAFLD patients, but effects on ALT and ALP are inconsistent. The clinical relevance for general liver health is still uncertain.

Does chlorella lower cholesterol?

Modest reductions in total cholesterol and LDL-C have been reported, but it does not affect triglycerides or HDL-C. The effect size is small and may not be clinically meaningful for most individuals.

Is chlorella safe?

Generally safe for most adults in the short term, but gastrointestinal issues and allergic reactions can occur. Long-term safety data are not yet established.

How should chlorella be taken?

Prefer cracked-cell products, typically 2–5 grams per day, taken with meals. Start with a lower dose to assess tolerance and gradually increase.

Are there any drug interactions?

No strong evidence of drug interactions, but theoretical risks exist with anticoagulants and antihypertensives. Consult a healthcare professional if taking these medications.

Can children or pregnant women take chlorella?

Safety has not been established in these populations. It is best to avoid use unless under direct medical supervision.

Research Sources

https://pmc.ncbi.nlm.nih.gov/articles/PMC7850816/ – This systematic review and meta-analysis of 7 RCTs found that Chlorella vulgaris supplementation significantly reduced AST levels, especially in NAFLD patients. While a subgroup showed modest ALT reduction, no overall effect on ALT or ALP was observed, highlighting heterogeneity and the need for more research.
https://pubmed.ncbi.nlm.nih.gov/35331862/ – This systematic review and dose-response meta-analysis of RCTs in adults reported that Chlorella vulgaris supplementation led to modest but significant reductions in total cholesterol and LDL-C. However, it did not affect triglycerides or HDL-C, and the clinical significance of these modest effects remains uncertain.
https://examine.com/supplements/chlorella/ – This source provides a comprehensive overview of Chlorella, detailing its general safety profile, common side effects like gastrointestinal issues and allergic reactions, and the importance of cracked cell wall products for bioavailability. It also notes the lack of long-term safety data and specific population considerations.
https://www.mdpi.com/2072-6643/17/6/943 – This review discusses the antioxidant properties of Chlorella, noting that preclinical and some human studies suggest an increase in antioxidant enzyme activity. However, it emphasizes the limited high-quality human RCT data to fully support these claims, indicating an area for further research.