Research review
Does chlorella help with heart disease, or cause heart palpitations?
No human trial has tested chlorella against a heart disease diagnosis, heart attack or stroke — the human research measures risk-factor markers like blood pressure and cholesterol instead, with mixed results. We found no case report or trial linking chlorella to heart palpitations either.
The evidence doesn't support chlorella as a treatment for heart disease — no human trial has tested it against a heart attack, stroke, or a heart disease diagnosis. Human research instead measures risk-factor markers, mainly blood pressure and cholesterol, with mixed results. We also found no case report linking chlorella to heart palpitations or a racing heart.
What the evidence doesn't support
It doesn't support chlorella as a way to prevent, treat or reduce the risk of heart disease as a diagnosed condition — no trial we found measured a heart disease outcome (a heart attack, stroke, or a cardiologist's diagnosis) at all, in chlorella users or anyone else. The human research instead measures indirect risk markers, and even those results disagree across studies, covered fully in does chlorella help with blood pressure? and does chlorella help with cholesterol?. It also doesn't support the idea that chlorella causes heart palpitations, an irregular heartbeat, or a racing heart — we found no case report or trial describing that effect, in either direction.
What the trials found
No human trial has measured chlorella against heart disease, a heart attack or a stroke directly. What exists instead are risk-factor studies: a 2025 meta-analysis of 12 chlorella trials found no significant effect on blood pressure or lipids, while an older 2018 meta-analysis of 19 trials found modest reductions in total cholesterol, LDL cholesterol and blood pressure, concentrated in trials using more than 4 grams a day for 8 or more weeks. Neither of those measured a heart disease diagnosis or event — they measured lab values used as risk markers, which is a different, indirect kind of evidence.
Animal research goes a step further mechanistically but is still animal research, not human evidence. A study feeding rats and hamsters a high-fat diet, with or without chlorella added, found the animals given chlorella had lower triglycerides, total cholesterol and LDL cholesterol than high-fat-diet animals without it, and the paper's authors discussed this in terms of reduced coronary heart disease risk based on the cholesterol ratio. That's a real finding, in rats and hamsters, using a lab diet model — it has not been tested in people, and no human trial has confirmed the same effect translates to an actual reduction in heart disease risk.
On heart rate specifically: a small crossover trial in 14 trained male cyclists found chlorella (6 g/day for 21 days) was associated with a lower average heart rate during submaximal endurance exercise compared with placebo, alongside lower lactate and higher sprint power. That's a heart-rate finding, but a narrow, exercise-specific one, in trained athletes during a workout — it isn't evidence about resting heart rate, palpitations, or heart health in daily life.
Questions people ask
Does chlorella help with heart disease?
No human trial has tested chlorella against heart disease itself. The related human research measures blood pressure and cholesterol as risk markers, with mixed results — see the dedicated reviews linked above.
Can chlorella cause heart palpitations?
We found no case report or trial linking chlorella to heart palpitations, an irregular heartbeat, or a racing heart. If you're experiencing palpitations while taking chlorella or anything else, that's a symptom to bring to a doctor rather than something to self-diagnose from an ingredient list.
Does chlorella affect heart rate?
Two small trials in athletic populations found a lower heart rate during exercise at 6 grams a day — an exercise-specific finding in trained or healthy young adults, not evidence about resting heart rate generally.
When to talk to a doctor
Heart disease is diagnosed and managed by a doctor, often with monitoring, lifestyle changes and medication, and heart palpitations always deserve a medical evaluation rather than a guess about which supplement might be responsible. Chlorella is not a treatment for heart disease, and nothing in the research above supports using it as a substitute for cardiac care. If you have a diagnosed heart condition or take heart medication, ask a doctor before adding chlorella.
Sources
- The Role of Chlorella and Spirulina as Adjuvants of Cardiovascular Risk Factor Control: A Systematic Review and Meta-Analysis of Randomised Controlled Trials The most recent, largest meta-analysis of chlorella trials found no significant effect on blood pressure or lipid levels, in contrast to spirulina, which showed a small effect on diastolic blood pressure in the same review.
- Effect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trials A 2018 meta-analysis of 19 trials found lower total cholesterol, LDL, blood pressure and fasting glucose with chlorella than with placebo, concentrated in trials using more than 4 g/day for 8 or more weeks in unhealthy or hypertensive populations; triglycerides, HDL and BMI did not change significantly.
- Preventing dyslipidemia by Chlorella pyrenoidosa in rats and hamsters after chronic high fat diet treatment In rats and hamsters fed a high-fat diet, adding chlorella to the diet lowered triglycerides, total and LDL cholesterol compared with high-fat diet alone — an animal dyslipidemia study, not a human trial or a direct measure of heart disease.
- The Efficacy of Chlorella Supplementation on Multiple Indices of Cycling Performance A 21-day, 6 g/day chlorella trial in 14 trained male cyclists found lower lactate and heart rate during submaximal endurance testing and higher power during sprint testing, with no change in a longer time trial or lactate threshold.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.