How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Chlorella
Chlorella: slightly lower total and LDL cholesterol, and blood pressure, in several meta-analyses whose certainty is judged to be very low. Nothing in type 2 diabetics, and sports effects drawn from small trials.
Benefits
- Cholesterol: across 19 trials (797 people), total cholesterol drops by 9.09 mg/dl and LDL by 8.32 mg/dl, especially beyond 8 weeks and 4 g per day.
- Most recent meta-analysis: across 24 studies, LDL drops by 6.20 mg/dl, total cholesterol by 8.03 mg/dl, and weight by 1.28 kg, with a slightly lower high-sensitivity CRP.
- Blood pressure: across 19 trials, systolic drops by 4.51 mmHg and diastolic by 1.64 mmHg, especially in hypertensive individuals.
- Dietary cholesterol excess: with three eggs per day for 4 weeks, LDL rose by 1.7% with chlorella (5 g per day) vs. 14.3% with placebo, in 34 adults.
- Liver: across 7 trials, AST (a liver enzyme) drops by 9.15 U/L, and more so in individuals with non-alcoholic fatty liver disease.
- Cycling: in 14 trained cyclists, 6 g per day for 21 days lowered lactate and heart rate during moderate exertion, and raised average sprint power from 9.0 to 9.5 W/kg.
- Defenses: in 26 athletes, 6 g per day increased salivary IgA (83 vs. 54 µg/min with placebo after 4 weeks); in 51 adults, 5 g per day for 8 weeks increased NK cell activity.
- Vitamin B12-deficient vegetarians: in 17 people, 9 g per day for 60 days reduced methylmalonic acid, the marker of deficiency, by about 34%.
Precautions
Tolerance: in 124 adults aged 50 and over, side effects were comparable to placebo, except for fatigue, which was more frequent at 200 mg per day (44% vs. 19%). Over 12 weeks, no side effects or biological abnormalities in 80 people taking GABA-enriched chlorella. Limitations: certainty: the 2026 meta-analysis on 24 studies rates the evidence as low for BMI and very low for the rest. Conflicting results: a 2025 meta-analysis (12 studies on chlorella) finds no clear effect on blood pressure or blood lipids. Triglycerides and HDL: no significant change, neither across 19 trials nor 10 trials. Type 2 diabetes: 1.5 g per day for 8 weeks changed nothing regarding blood sugar, lipids, or weight in 84 patients. Liver: the 7 trials on hepatic steatosis all come from Iran, with very low certainty; another meta-analysis sees neither ALT nor alkaline phosphatase decrease. Vaccine: in 124 adults aged 50 and over, no better response to the flu vaccine, except in the 50 to 55 age subgroup. Sport: nothing on VO2max, the 16.1 km time trial, or the lactate threshold; the two trials involve 14 and 20 people. Bowel transit: in 40 constipated people, no more bowel movements or blood folate than with the placebo. Vitamin B12: the trial in vegetarians was open-label, on 17 people, without a placebo.
Recommended dosage
5 or 6 g per day in most trials; the drop in cholesterol and blood pressure mainly stands out above 4 g per day and 8 weeks.
How to take it
- Dose: 5 or 6 g per day in most trials; at 1.5 g per day for 8 weeks, nothing changed in 84 type 2 diabetics.
- Duration: across 19 trials, the drop in cholesterol and blood pressure mainly stands out from 8 weeks onwards and above 4 g per day.
- Analyses diverge: another meta-analysis (10 trials) only sees the drop in LDL at doses up to 1500 mg per day, not beyond.
- Sport: in 20 young adults, 2 days at 6 g per day were enough to lower exertion lactate, without changing VO2max.
- Species: trials use Chlorella vulgaris or Chlorella pyrenoidosa; the 2009 blood pressure trial used GABA-enriched chlorella.
- Vitamin B12: the trial in vegetarians provided 9 g per day for 60 days.
Did you know?
Three eggs a day for four weeks raised LDL cholesterol by 14.3% with a placebo, but by only 1.7% with 5 g of chlorella a day.
What the studies say
This systematic review and meta-analysis of 24 studies explored the benefits of Chlorella on various health biomarkers in the general population. Chlorella supplementation was associated with significant reductions in body fat mass, BMI, weight, total and LDL cholesterol, triglycerides, as well as other metabolic and inflammatory markers. However, the authors emphasize that the overall certainty of the evidence is very low.
Mardani H, Karimi MA, Sharifi M, Ghazvineh D, Yari Z, Jafari A. — Nutrition & diabetes (2026) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more