Spirulina

We evaluated 156 human studies on Spirulina, including 76 randomised controlled trials and 29 meta-analyses or systematic reviews; the controlled studies include 6,760 participants in total. As of 8 October 2026.

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1. What Is Spirulina? Occurrence, Origin and Forms

Spirulina is the dried biomass of filamentous cyanobacteria of the genus Arthrospira, mainly Arthrospira platensis and Arthrospira maxima. It grows naturally in alkaline soda lakes and is today cultivated in open ponds and closed systems. Traditionally it is eaten as dried cakes; today it serves mainly as a dietary supplement and as a protein-rich food ingredient.

Natural occurrences are in alkaline, mineral-rich soda lakes in Africa, Asia and Central America; for commercial use it is grown in culture ponds or photobioreactors. It is used as a powder, tablet or food additive, and in studies mainly as the dried whole biomass.

Spirulina is obtained by cultivation in alkaline nutrient solutions, harvesting of the filaments and gentle drying into a dark green powder that is further processed into tablets or capsules. Studies examine mainly the dried whole biomass in powder, tablet or capsule form, as well as foods and beverages fortified with spirulina.

Forms and Preparations Studied

• Dried powder of the whole biomass
• Tablets and capsules
• Foods and beverages fortified with spirulina
• Fresh or frozen biomass
• Arthrospira platensis and Arthrospira maxima as different species

Not covered on this page:

• Chlorella and other green algae or microalgae such as Chlorella vulgaris
• Aphanizomenon flos-aquae and other wild-harvested cyanobacteria from lakes
• Phycocyanin isolated from spirulina as a single substance
• Products that mix several microalgae or additional active substances and are offered as blue-green algae

2. What Does Spirulina Do? Results by Area

How to read the table: counted are human studies whose results concern the area. “High” means at least one meta-analysis and two controlled studies showing improvement, or at least three controlled studies of which three quarters show improvement, with at least 300 participants in total. “Moderate” means at least two controlled studies showing improvement, as a majority, or one meta-analysis alongside controlled studies. “Low” means one controlled study showing improvement. Where an area has no controlled study, the strength of evidence is at most “low” (result “reviews only” or “observational data only”). Everything else is “unclear”. A study counts as showing improvement when at least half of its outcomes in this area improved. Reviews of combination products do not count as meta-analyses; results that only describe side effects or shares of users do not count as an effect. The same study is counted only once.

3. What the Studies Show in Detail

Spirulina, Body Weight and Body Composition: Human Studies

For body weight and body composition, meta-analyses are favorable, controlled individual studies mixed. Meta-analyses found lower body weight in adults 61819 and weight gain in malnourished children 4. Two randomized controlled trials found more weight loss with spirulina than with placebo, in multiple sclerosis 42 and with a low-calorie diet 62. A randomized crossover trial with Arthrospira maxima lowered body fat percentage even without training 103. Appetite decreased with spirulina compared with baseline 62; with strength training, hunger fell in all groups, most strongly with spirulina 54. Individual studies found no difference in weight 40, in anthropometric parameters 4668 or in body fat percentage 90. With mixtures containing chlorella and other algae 16, with structured training 13, with HIIT 69 or with turmeric 72, the effect cannot be attributed to spirulina alone. The robustness is high, but most studies are small and short.

Further studies in this area: 19 22 27 37 40 42 46 49 50 54 59 62 64 66 68 69 70 74 75 77 79 80 84 90 103 110 125 140 146 150

Spirulina and Blood Lipids: Human Studies

Meta-analyses found lower total and LDL cholesterol and triglyceride levels 56182628, also in type 2 diabetes 26 and in people with overweight 6; a meta-analysis on spirulina together with structured training also reports more favorable LDL and triglyceride levels as well as higher HDL cholesterol, although the result cannot be attributed to spirulina alone 13. In type 2 diabetes, triglycerides fell more than with placebo, and total and LDL cholesterol decreased 57; in people with HIV, blood lipids improved compared with baseline 39. In men with overweight, these improvements appeared mainly together with training 6070. A spirulina sauce lowered triglycerides and LDL cholesterol in type 2 diabetes, but not HDL cholesterol 75. In children with nephrotic syndrome, blood lipids fell with and without spirulina, numerically more with spirulina 112. No difference in blood lipids was found by a meta-analysis 8 as well as randomized controlled trials in healthy people and in women with overweight doing interval training 8292. The optimal amount, the significance of the species Arthrospira platensis compared with Arthrospira maxima and the question of whether the findings can be confirmed in healthy people without lipid metabolism disorders remain open.

Further studies in this area: 27 28 39 48 57 60 62 64 67 70 75 76 82 92 106 109 110 112 125 129 136 137 138 140 144 152 155

Spirulina, Blood Glucose and Metabolism: Human Studies

Meta-analyses found lower fasting glucose, also in type 2 diabetes 2628; randomized controlled studies confirmed this in type 2 diabetes, HIV infection and Alzheimer's dementia 385657. Insulin resistance and insulin levels also improved in a meta-analysis 18, a randomized controlled study 56 and a non-randomized study in obese men with and without interval training 110. Insulin sensitivity improved in several studies, including one with Arthrospira maxima and one with Arthrospira platensis compared with soy 566483. Sauces fortified with spirulina did not change fasting glucose, HbA1c and insulin in fatty liver and type 2 diabetes 6875. The robustness is high, since several meta-analyses and controlled studies are available, but many investigations are small, short and do not always distinguish between the Arthrospira species.

Further studies in this area: 56 57 59 64 68 69 75 82 83 97 99 110 117 125 127 136 137 139 140 144 151 152

Spirulina, Oxidative Stress and Antioxidants: Human Studies

Controlled trials found less lipid peroxidation, measured as malondialdehyde or TBARS 5568115; with local application in periodontal pockets in periodontitis, malondialdehyde fell only in saliva, not in blood 108. Total antioxidant capacity was also higher in several controlled trials 43495568. A meta-analysis confirmed lower malondialdehyde and a higher total antioxidant capacity 2. Inflammatory markers improved: a meta-analysis found lower levels of interleukin-6 and hs-CRP 18, randomized controlled trials in Alzheimer's dementia and overweight a lower hs-CRP 5662. Superoxide dismutase activity increased in older women with spirulina 48 and in COPD patients compared with baseline 109. In rugby players, F2α-isoprostanes increased after exhaustive exercise only with placebo; the study does not report a direct group comparison 95. In people with hypertension, glutathione peroxidase and oxidized glutathione increased with Arthrospira maxima powder compared with baseline 96. A randomized controlled trial with Arthrospira platensis salad dressing in hypertension, by contrast, found no difference in total antioxidant capacity and in hs-CRP 67. The evidence is overall high, but many studies include small groups and short durations, and the influence on clinical endpoints remains open.

Further studies in this area: 56 62 64 67 68 75 76 95 96 108 109 115 117 136 137 139 140 143 146 149 151 152 155

Spirulina and Physical Performance: Human Studies

A randomized crossover study with Arthrospira maxima in overweight men found a higher maximum oxygen uptake, with and without a training programme 61103104; another during arm crank exercise found a higher oxygen uptake until exhaustion 98. Time to exhaustion was prolonged in this study 103104 and in a placebo-controlled crossover study with runners 115. In the study with Arthrospira maxima, lactate accumulation also began later 103104; two further studies found more haemoglobin than with placebo 9498. By contrast, a randomized controlled study in rugby players found only a small, not confirmed advantage in jumping and sprinting and no difference in strength 90. Spirulina Nigrita® did not change strength and muscle soreness after exercise 116. In cyclists, a randomized controlled study found no difference in maximum performance, heart rate, oxygen uptake and time to exhaustion 94. A systematic review on spirulina as Arthrospira platensis reports a better oxygen uptake and exercise tolerance at submaximal exercise, but no difference in physical performance in strength athletes 25. A meta-analysis on spirulina, chlorella, brown algae polysaccharides and astaxanthin found a longer time to exhaustion and a trend towards higher VO2max 7; another on spirulina with structured training found a higher VO2max 13. In these mixtures, the share of spirulina alone cannot be attributed 713.

Further studies in this area: 90 91 94 98 103 105 115 116 138 143 146 153

Spirulina and Blood Pressure: Human Studies

Several meta-analyses found a lower diastolic blood pressure with spirulina, especially in high blood pressure and overweight 6810151828. Systolic blood pressure also fell in meta-analyses 101518; three small studies found a reduction only within the spirulina group, without a group comparison 677996. A systematic review reports an improvement in hypertension in metabolic syndrome 22; another considers an effect in postmenopausal women possible and calls for clinical trials on this 27. Endothelial function improved in overweight people with hypertension with Arthrospira maxima powder compared with baseline 79. These positive findings are contrasted by four randomized controlled trials in which blood pressure did not differ 46506882: one investigated Arthrospira platensis capsules in ulcerative colitis 46, one softgel capsules in depression 50, one a sauce fortified with Arthrospira platensis in non-alcoholic fatty liver disease 68 and one spirulina powder in healthy adults without hypercholesterolemia 82. A yogurt-like dessert fortified with Arthrospira platensis did not lower blood pressure in people with overweight and did not improve vascular values 52. The evidence is moderate: the meta-analyses are favorable, the controlled individual studies mostly without a confirmed difference; which amount and preparation works remains open.

Further studies in this area: 46 50 52 67 68 79 82 96 97 125 137 138 139 140 144 152

Spirulina and Allergic Conditions (e.g., Allergic Rhinitis): Human Studies

A systematic review found less runny nose, blocked nose and itching in allergic rhinitis; the authors rate the evidence as very low because of only two studies 11. The robustness is moderate: the findings are based mainly on review articles; larger randomized studies stating species, form and amount are still pending.

Spirulina: Further Outcomes in Studies

Investigated were predominantly Arthrospira platensis, in the form of powder, capsules and tablets as well as fortified foods; mixtures with other microalgae or additives cannot be attributed to spirulina alone. The transferability to other spirulina species and forms as well as long-term effects remain open, since many studies were small and of short duration.

Further studies in this area: 24 25 29 30 31 32 33 34 35 36 37 38 40 41 42 43 44 45 46 47 48 49 50 51 53 55 56 58 59 63 65 68 69 70 71 73 75 77 78 80 81 84 85 86 87 88 89 91 92 93 94 95 99 100 101 102 105 106 107 108 111 113 114 115 116 119 120 121 123 124 126 128 129 130 131 132 134 136 137 138 139 140 141 142 143 145 146 147 148 149 150 152 154 155

4. How Is Spirulina Dosed? Preparation, Dose and Duration in Studies

The studies predominantly used dried powder of the whole biomass, tablets, capsules as well as foods and drinks enriched with spirulina. Mainly Arthrospira platensis and Arthrospira maxima were studied; the table shows the amounts tested. Individual studies tested mixtures, for example with chlorella, other algae, turmeric or together with training, so the contribution of spirulina cannot be attributed on its own there.

5. Is Spirulina Safe? Side Effects in Studies

Tolerability is predominantly described as good in the studies; in some cases no side effects were observed 36. Individual studies reported a slight increase in creatinine 4049; a skin gel with spirulina extract caused only very few local side effects 113. Review articles describe rare hypersensitivity reactions to spirulina up to anaphylaxis 133135.

6. What Remains Open: Limits of the Evidence

• Many studies are small and of short duration, which limits the transferability of the results.
• The optimal amount and form of preparation is open; the studies used different forms and amounts.
• The difference between Arthrospira platensis and Arthrospira maxima is hardly studied.
• Many studies provide no information on manufacturer funding, which leaves the risk of conflicts of interest open.
• Whether the findings can be transferred to healthy people without metabolic disorders is largely unclear.

7. Bottom Line: What Is Established About Spirulina

Spirulina is the dried biomass of filamentous cyanobacteria of the genus Arthrospira, predominantly Arthrospira platensis and Arthrospira maxima, and is used as a dietary supplement or fortified food. For blood glucose and oxidative stress, controlled trials predominantly show improvements; for body weight, blood lipids and physical performance, meta-analyses are mostly favorable, while the individual studies are inconsistent.

For allergic rhinitis, the evidence is moderate, and the study situation there is less clear. For blood pressure and other endpoints, there are both positive and negative findings. Many studies are small, short and do not always distinguish between the species or forms. The optimal amount, long-term effects and the influence of combination products remain open.