Does Spirulina Help Cholesterol, Blood Pressure or Weight?

Spirulina may help a little with weight, and may modestly lower blood pressure and LDL cholesterol. The trials are small and results conflict.

Published October 2026

Short answer

Spirulina may help a little with weight. The evidence for blood pressure and cholesterol is early, and the results conflict. Evidence grade C (Limited). Several meta-analyses of small trials; downgraded for inconsistency and, for blood pressure and cholesterol, for surrogate markers.

Key takeaways

Pooled trials show spirulina lowers body weight by roughly 0.8 to 1.9 kg more than placebo, though the trials are small and vary widely [1][2][3].
Blood pressure fell by a few mmHg in pooled trials, but a 2026 trial of 64 adults found no change [4][5].
LDL cholesterol results conflict: some meta-analyses report lower LDL, while a 2025 review of 9 trials found no significant change in lipids [4][6].
Some blue-green algae products are contaminated with liver-damaging microcystins, but spirulina-only products tested in one study were free of them [7].
No trial we read tested interactions with most medicines; a 2-week study in 24 adults found no change in clotting markers [8].

The short version

Spirulina may help a little with weight, and it may modestly lower blood pressure and “bad” LDL cholesterol. The clearest result is for weight: pooled trials show a loss of roughly 0.8 to 1.9 kg more than placebo [1][2][3]. The blood pressure and cholesterol results are weaker, and some trials and one 2025 review found no effect [6][5].

What the spirulina studies show

Weight. In a network analysis of 111 trials of 18 supplements, spirulina lowered body weight by 1.77 kg compared with placebo [3]. A separate meta-analysis found 1.85 kg less weight than controls, but the trials differed widely [2]. In a 12-week trial of 52 adults with overweight or obesity, 38 of whom finished, spirulina with a calorie-restricted diet led to more weight loss than placebo with the same diet [9]. Not every trial agreed. In a 12-day study of 40 wrestlers losing weight, body mass fell by about 3 kg in both groups, and only body fat fell further with spirulina [10].

Blood pressure. Three meta-analyses of trials found systolic pressure about 4 to 5 mmHg lower and diastolic pressure about 3 to 7 mmHg lower with spirulina [11][12][4]. A 2025 review of 29 trials of edible algae found spirulina the most effective of the algae tested [13]. Single trials were less consistent. In 41 adults with high blood pressure who finished an 8-week trial, a spirulina salad dressing lowered systolic and diastolic readings compared with a placebo dressing [14]. In 64 overweight adults who ate a spirulina-enriched dessert for 8 weeks, blood pressure did not change [5]. A 6-month trial of 120 healthy older adults found no overall difference; the 8% drop appeared only in a subgroup with high-normal blood pressure and stiff arteries [15].

Cholesterol. Results on LDL cholesterol are mixed. A 2016 meta-analysis of 7 trials reported LDL about 41 mg/dL lower with spirulina [16]. A 2019 meta-analysis of people with metabolic syndrome found about 19 mg/dL lower [17]. A 2023 meta-analysis of 20 trials (1,076 people) reported lower LDL and triglycerides [18]. A 2025 review of 35 trials found about 8 mg/dL lower and rated its LDL evidence as low quality [4]. A 2025 review of 9 spirulina trials found no significant change in lipids [6]. In a 12-week trial of obese adults, total cholesterol fell with 1 g a day of spirulina, while LDL did not change [19].

The nuances

Who it may apply to. The most consistent results come from people with overweight, obesity or high blood pressure [12][20]. A 2025 review of overweight and obese adults found that spirulina alone reduced body weight and several lipid measures, but its overall effect on body composition and blood sugar looked limited. Adding exercise improved some lipid results in the same review [20].

Doses and forms. Doses in the trials cited here ranged from 1 g to 4.5 g a day, lasting from 12 days to 6 months [19][21][15][10]. A 2025 review suggested that more than 3 g a day for at least 12 weeks gave the clearest blood pressure effect [13]. Some trials tested forms other than plain powder, such as a dressing, a dessert or a silicon-enriched product, so their results may not carry over [14][5][15].

Safety. A 3-month trial in 60 adults with type 2 diabetes on metformin reported no adverse events [22]. A 2-week study of a high-dose extract (2.3 g a day of a phycocyanin extract, in 24 people) found no change in clotting or platelet markers [8]. Some blue-green algae products contain microcystins, which damage the liver. In an Italian study of 17 brands, spirulina-only products were free of them, while products containing Aphanizomenon were contaminated [7]. Microcystin levels in data from 95 French spirulina producers stayed within the safe regulatory level [23]. We found no upper safe limit and no studies of pregnancy, breastfeeding or kidney disease.

Conflicts of interest. One 2025 review had two authors employed by the company Sea4Us [6]. A 2025 trial of a silicon-enriched spirulina had an author employed by the company that supplied the product [15].

What this means for you

Spirulina is not a treatment for high blood pressure, high cholesterol or obesity. If you are thinking about it for any of these, talk with a doctor first, especially if you take blood pressure or cholesterol medicines, diabetes medicines or blood thinners. Choose products that are tested for contamination, since some blue-green algae products have been found to contain microcystins [7][23].

Go deeper

Spirulina — Spirulina may help a little with body weight, with roughly 0.8 to 1.9 kg more loss than placebo in pooled trials.