Review · Molecules (Basel, Switzerland) · 2026Conflicts declared

Chlorella and spirulina: what the evidence shows

Rzeski W, Rzeska W · Free full text

In people, spirulina supplements were linked to small improvements in cholesterol, blood sugar and inflammation, while chlorella was linked to lower blood pressure and better antioxidant levels.

Most of the detailed mechanism work was done in animals and cells.

What they found

Studies in people

Cholesterol and lipids

In people, spirulina supplements reduced total cholesterol by about 10 to 20 mg/dL, LDL cholesterol by about 8 to 15 mg/dL, and triglycerides by about 15 to 30 mg/dL. These effects were seen across different groups, including people with dyslipidemia and metabolic syndrome.

Blood sugar and insulin

Human trials found improvements in fasting blood glucose and insulin resistance in people with type 2 diabetes or metabolic syndrome, especially at doses of 2 g/day or more for at least 8 to 12 weeks. The effects were moderate.

Inflammation and CRP

Spirulina supplementation lowered C-reactive protein (CRP) in people with metabolic syndrome, obesity or type 2 diabetes. Effects on other inflammatory markers like IL-6 and TNF-alpha were mixed.

Blood pressure

Chlorella supplementation lowered systolic blood pressure in people with prehypertension. Spirulina also showed some blood pressure effects, but the evidence was stronger for chlorella.

Antioxidants in people

Both chlorella and spirulina improved markers of oxidative stress in human trials, such as lower malondialdehyde (MDA) and higher total antioxidant capacity. Doses ranged from 1 to 8 g/day and lasted 4 to 24 weeks.

Immune effects in people

In healthy volunteers, an 8-week trial of chlorella (5 g/day) increased natural killer cell activity and levels of IFN-gamma and IL-1 beta. A spirulina extract also boosted natural killer cell activity in people.

Animal and lab studies

Mechanisms in animals and cells

Lab and animal studies suggest these microalgae activate Nrf2 antioxidant pathways, block NF-kB inflammation, and turn on AMPK energy-sensing pathways. These effects have not been confirmed in people.

Gut bacteria and detox

Animal studies show chlorella can change gut bacteria, increase short-chain fatty acid production, and bind heavy metals. Human data on these effects are limited.

What the authors conclude

“Overall, chlorella and spirulina emerge as complementary multi-pathway biological response modulators with potential applications in preventive and integrative medicine.”

Rzeski W, Rzeska W, 2026

Also in their conclusions

They say chlorella and spirulina act as complementary multi-pathway biological response modulators with potential in preventive medicine.
They note that heterogeneity in study design and product standardization limits definitive conclusions.
They call for more research, including trials that directly compare spirulina alone, chlorella alone, and the two combined.

How it was done

The authors say the field is fragmented, with many studies looking at single outcomes and not connecting molecular mechanisms to clinical results. They wanted to bring together what is known about how these microalgae work in the body.

They reviewed published studies on chlorella and spirulina, including lab and animal experiments and human trials. Human trials used doses of 1 to 10 g/day and lasted from 4 to 24 weeks.

What it can’t tell you

Most of the detailed mechanism studies were done in animals or cells, so they cannot show what happens in people.
The human trials used different doses, durations and product types, which makes it hard to compare results across studies.
There are no long-term human studies looking at aging outcomes like frailty or cognitive decline.

Who paid

Conflicts: The authors declare no conflicts of interest.
Authors work at: Maria Curie-Skłodowska University, Poland; Lublin Medical University, Poland

The paper

Title: Chlorella and Arthrospira (Spirulina) as Multi-Pathway Biological Response Modulators: Molecular Mechanisms, Signaling Pathways and Clinical Evidence
Type: ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
Evidence: Studies in people · animals · lab
Summarised from: Full text
Licence: CC BY. Words in quotation marks are the authors’; the rest is our summary.
Cite: Rzeski W, Rzeska W (2026). Chlorella and Arthrospira (Spirulina) as Multi-Pathway Biological Response Modulators: Molecular Mechanisms, Signaling Pathways and Clinical Evidence. Molecules (Basel, Switzerland). doi:10.3390/molecules31101595Free full text PubMed 42197149 DOI

Summary written 29 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error