What the science actually says.

Daily spirulina supplementation significantly increased haemoglobin, serum ferritin, and transferrin saturation compared to controls. The spirulina group saw haemoglobin rise by 1.2 g/dL versus 0.3 g/dL in the control group.

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Spirulina supplementation increased mean corpuscular haemoglobin concentration and improved immune variables including NK cell cytotoxic activity. The most significant improvements were seen in participants who were mildest deficient at baseline.

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Even at the low dose of 1 g/day, spirulina supplementation significantly improved haemoglobin, serum iron, and serum ferritin in anaemic adolescent girls. The improvement was statistically comparable to an iron tablet group at the same total elemental iron dose.

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Spirulina supplementation reduced total cholesterol by 10%, LDL by 15%, and triglycerides by 16% compared to baseline, while modestly raising HDL. Systolic blood pressure fell an average of 6 mmHg in the spirulina group.

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In patients with type 2 diabetes, 2 g/day spirulina significantly reduced fasting blood glucose, HbA1c, total cholesterol, LDL, VLDL, and triglycerides. HDL increased modestly.

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Spirulina supplementation significantly reduced body weight, BMI, waist circumference, and serum triglycerides. C-reactive protein (CRP), a marker of systemic inflammation, fell significantly in the spirulina group.

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Spirulina at 1.5 g/day significantly reduced liver enzymes (ALT, AST), total cholesterol, LDL, triglycerides, and oxidative stress markers in NAFLD patients. Ultrasound assessment showed a reduction in fatty infiltration grade in the spirulina group.

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Systematic review of clinical trials concluded that spirulina consistently reduces total cholesterol, LDL, and triglycerides across diverse populations, and raises HDL. Anti-inflammatory and antioxidant properties are well-evidenced. Authors grade the cardiovascular evidence as the strongest among spirulina's claimed benefits.

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Spirulina supplementation significantly reduced total cholesterol, LDL, and triglycerides while improving antioxidant enzyme activity (superoxide dismutase, glutathione peroxidase) in elderly adults. HDL increased modestly.

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Systematic review covering 2010–2020 found consistent evidence for spirulina's effects on lipid profiles, blood glucose, and oxidative stress markers across RCTs. Emerging evidence for gut microbiome modulation — spirulina appears to increase Lactobacillus and Bifidobacterium populations in preliminary studies.

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Meta-analysis found statistically significant reductions in malondialdehyde (oxidative stress marker) and CRP (inflammation marker), alongside significant improvements in total cholesterol, LDL, HDL, and systolic blood pressure compared to placebo.

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Spirulina supplementation produced a statistically significant reduction in body weight (mean −0.9 kg), BMI, and waist circumference compared to placebo. Effects were stronger in studies using higher doses (≥ 4 g/day) and longer duration (≥ 12 weeks).

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Systematic review of spirulina human clinical trials across multiple health outcomes. Consistent evidence for lipid improvements and modest glycaemic effects. Emerging evidence for immune modulation (NK cell activity, anti-allergy) and antioxidant biomarker reduction. No serious adverse events reported across the reviewed trials.

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In patients with type 2 diabetes, 2 g/day spirulina significantly reduced fasting blood glucose, HbA1c, total cholesterol, LDL, VLDL, and triglycerides. HDL increased modestly.

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Spirulina added to standard anti-diabetic therapy significantly reduced fasting blood glucose and postprandial blood glucose. HbA1c fell by 1% over 12 weeks — a clinically significant reduction.

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Systematic review covering 2010–2020 found consistent evidence for spirulina's effects on lipid profiles, blood glucose, and oxidative stress markers across RCTs. Emerging evidence for gut microbiome modulation — spirulina appears to increase Lactobacillus and Bifidobacterium populations in preliminary studies.

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Spirulina supplementation produced a statistically significant reduction in body weight (mean −0.9 kg), BMI, and waist circumference compared to placebo. Effects were stronger in studies using higher doses (≥ 4 g/day) and longer duration (≥ 12 weeks).

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Pooled analysis found spirulina supplementation produced a statistically significant reduction in fasting blood glucose (mean −0.85 mmol/L, p<0.001) across 7 RCTs. No significant effect was found on HbA1c or fasting insulin. Effect was stronger in studies with higher baseline blood glucose.

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Spirulina at 2 g/day significantly reduced fasting blood glucose (by approximately 1.6 mmol/L) and HbA1c in type 2 diabetic patients. Lipid parameters also improved. The effect was seen at a relatively low dose.

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Systematic review of spirulina human clinical trials across multiple health outcomes. Consistent evidence for lipid improvements and modest glycaemic effects. Emerging evidence for immune modulation (NK cell activity, anti-allergy) and antioxidant biomarker reduction. No serious adverse events reported across the reviewed trials.

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Spirulina supplementation reduced total cholesterol by 10%, LDL by 15%, and triglycerides by 16% compared to baseline, while modestly raising HDL. Systolic blood pressure fell an average of 6 mmHg in the spirulina group.

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Meta-analysis of 7 RCTs found spirulina supplementation significantly reduced systolic blood pressure (mean reduction −4.6 mmHg) and diastolic blood pressure (mean reduction −3.0 mmHg) compared to control. Effect was stronger in participants with elevated baseline blood pressure.

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Systematic review of clinical trials concluded that spirulina consistently reduces total cholesterol, LDL, and triglycerides across diverse populations, and raises HDL. Anti-inflammatory and antioxidant properties are well-evidenced. Authors grade the cardiovascular evidence as the strongest among spirulina's claimed benefits.

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Meta-analysis found statistically significant reductions in malondialdehyde (oxidative stress marker) and CRP (inflammation marker), alongside significant improvements in total cholesterol, LDL, HDL, and systolic blood pressure compared to placebo.

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Spirulina at 4.5 g/day significantly reduced systolic blood pressure by approximately 8 mmHg and diastolic by approximately 6 mmHg in stage 1 hypertensive adults. Reductions in lipid peroxidation markers were also observed.

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Spirulina supplementation increased time to fatigue by 30% during a maximum intensity treadmill run (from 2.05 to 2.67 min), and significantly reduced exercise-induced lipid peroxidation and muscle damage markers compared to placebo.

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Spirulina supplementation led to modest improvements in maximal oxygen uptake (VO2max) and peak power output during graded exercise testing. Fatigue onset was delayed compared to placebo.

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Spirulina plus aerobic exercise produced significantly greater reductions in body fat percentage and BMI than exercise alone. Spirulina alone (no exercise) showed non-significant improvements. The spirulina-plus-exercise group also showed better VO₂max improvements than exercise only.

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Spirulina significantly reduced nasal discharge, sneezing, nasal congestion, and itching scores versus placebo. The IgE levels were reduced in the spirulina group, suggesting a modulation of the allergic immune response rather than simple symptom suppression.

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Spirulina supplementation significantly reduced body weight, BMI, waist circumference, and serum triglycerides. C-reactive protein (CRP), a marker of systemic inflammation, fell significantly in the spirulina group.

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Phycocyanin (PC), spirulina's primary pigment, demonstrated potent free-radical scavenging, anti-inflammatory (COX-2 inhibition), and neuroprotective properties across multiple in-vitro and animal models. PC selectively scavenges hydroxyl radicals and peroxyl radicals.

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Systematic review of clinical trials concluded that spirulina consistently reduces total cholesterol, LDL, and triglycerides across diverse populations, and raises HDL. Anti-inflammatory and antioxidant properties are well-evidenced. Authors grade the cardiovascular evidence as the strongest among spirulina's claimed benefits.

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Systematic review covering 2010–2020 found consistent evidence for spirulina's effects on lipid profiles, blood glucose, and oxidative stress markers across RCTs. Emerging evidence for gut microbiome modulation — spirulina appears to increase Lactobacillus and Bifidobacterium populations in preliminary studies.

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Meta-analysis found statistically significant reductions in malondialdehyde (oxidative stress marker) and CRP (inflammation marker), alongside significant improvements in total cholesterol, LDL, HDL, and systolic blood pressure compared to placebo.

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Spirulina supplementation significantly inhibited IL-4 production compared to placebo — IL-4 is a cytokine central to the Th2 immune response that drives allergic inflammation. The intervention appeared to shift immune function away from Th2 dominance without suppressing overall immune activity.

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C-phycocyanin demonstrated direct free-radical scavenging activity (particularly against peroxyl and hydroxyl radicals), inhibited COX-2 and 5-LOX enzyme activity, and showed neuroprotective activity in oxidative stress models. Phycocyanin activity was dose-dependent and distinct from vitamin E.

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Comprehensive review of contaminant data from commercial spirulina and chlorella products found that heavy metals (lead, arsenic, cadmium), microcystins, and microbial contaminants are the primary safety concerns. Open-pond cultivation in areas with agricultural runoff carries higher contamination risk. Third-party testing on each production batch is the only reliable mitigation.

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Spirulina extract inhibited the genotoxic effects of aflatoxin B1 and arsenic in human cell cultures. The effect was attributed to spirulina's antioxidant and anti-mutagenic properties rather than direct metal chelation.

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Spirulina contains significant levels of phenylalanine — approximately 2.5–3.0 g per 100 g dry weight. This is relevant for people with phenylketonuria (PKU), for whom dietary phenylalanine must be strictly controlled. The study confirmed that spirulina supplementation is contraindicated in PKU at any meaningful dose.

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Case series and review found that prolonged high-dose spirulina supplementation (> 10 g/day for > 6 months) was associated with thyroid abnormalities in some individuals, potentially linked to spirulina's iodine content and immune-modulating properties. No such association was observed at typical consumer doses.

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