Spirulina and Blood Pressure

    Spirulina, a nutrient-dense blue-green microalgae, has been studied for its potential effects on body weight, blood pressure, cholesterol levels, and blood vessel health. Several human clinical trials have explored whether daily spirulina supplementation can support cardiovascular and metabolic health.

    In one randomized, double-blind, placebo-controlled study, 40 adults with high blood pressure—but no heart disease—were randomly assigned to receive either 2.0 grams of Hawaiian spirulina daily or a placebo for three months (1). Researchers measured body weight, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), and a stiffness index (SI), which reflects blood vessel flexibility. After three months, no meaningful changes were observed in the placebo group. In contrast, the spirulina group showed significant improvements. BMI decreased from 26.9 ± 3.1 to 25.0 ± 2.7 kg/m² (p = 0.0032), and body weight declined from 75.5 ± 11.8 kg to 70.5 ± 10.3 kg (p < 0.001). Systolic blood pressure decreased from 149 ± 7 mmHg to 143 ± 9 mmHg (p = 0.0023), a reduction of approximately 6 mmHg. Even modest reductions of this magnitude are considered clinically meaningful, as small decreases in systolic blood pressure are associated with lower cardiovascular risk. Arterial stiffness also improved, with SI decreasing from 7.2 ± 0.6 m/s to 6.9 ± 0.7 m/s (p < 0.001) (1).

    In addition to effects on weight and blood pressure, researchers have examined whether spirulina influences markers of vascular damage and oxidative stress. In a small pilot study involving 16 patients with systemic arterial hypertension who were already taking ACE inhibitors, participants were randomly assigned to take either 4.5 grams of Spirulina daily or a placebo for 12 weeks (2). Investigators measured markers of endothelial dysfunction and oxidative stress, including sVCAM-1, sE-selectin, endothelin-1, and several antioxidant enzymes. After 12 weeks, the spirulina group demonstrated significant improvements (p < 0.05). Systolic blood pressure decreased from 140.38 ± 9.04 to 126.50 ± 5.53 mmHg, while the placebo group remained largely unchanged (140.75 ± 7.03 to 140.00 ± 6.05 mmHg). Markers associated with blood vessel damage were reduced, and glutathione peroxidase activity increased, suggesting enhanced antioxidant defense (2).

    Spirulina has also been evaluated as a functional food ingredient. In a triple-blind randomized clinical trial, 48 patients with hypertension were assigned to consume either a salad dressing containing 2 g of spirulina platensis powder per day or a placebo dressing for 8 weeks; 41 participants completed the study (3). After two months, the spirulina group experienced significant reductions in systolic blood pressure from 144.72 ± 2.98 to 138.46 ± 2.98 mmHg (p = .02) and diastolic blood pressure from 96.60 ± 1.76 to 92.58 ± 2.21 mmHg (p = .03). Serum triglycerides decreased from 195.77 ± 16.74 to 175.13 ± 16.46 mg/dL (p = .01). The placebo group showed no meaningful changes. Although total antioxidant capacity and hs-CRP levels did not differ significantly, the reductions in blood pressure and triglycerides suggest potential cardiometabolic benefits when spirulina is incorporated into commonly consumed foods (3).

    In another study, 36 adults (16 men and 20 women, ages 18–65) consumed 4.5 grams of spirulina daily for 6 weeks without modifying their diet or lifestyle (4). Blood glucose and the liver enzyme AST did not change significantly. However, blood lipids improved. Triglycerides decreased from 233.7 ± 177.8 to 167.7 ± 100.7 mg/dL (p < 0.001), total cholesterol declined from 181.7 ± 37.5 to 163.5 ± 34.4 mg/dL (p < 0.001), and HDL cholesterol increased from 43.5 ± 14.4 to 50 ± 18.8 mg/dL (p < 0.01). LDL cholesterol was also significantly reduced. Blood pressure improved in both men and women. In men, systolic blood pressure decreased from 121 ± 9 to 111 ± 8 mmHg (p < 0.01), and diastolic blood pressure dropped from 85 ± 6.5 to 77 ± 9 mmHg (p < 0.01). In women, systolic blood pressure fell from 120 ± 9.5 to 109 ± 11 mmHg (p < 0.002), and diastolic blood pressure decreased from 85 ± 11 to 79 ± 7.5 mmHg (p < 0.03) (4). These findings suggest improvements in lipid metabolism and blood pressure regulation.

    Researchers have also examined silicon-enriched spirulina in older adults. In a study of 120 participants aged 60–75, individuals were randomly assigned to take 3.5 grams daily or a placebo for six months (5). When all participants were analyzed together, no major differences were detected. However, among those with systolic blood pressure between 130 and 150 mmHg and increased arterial stiffness, meaningful improvements were observed. In this subgroup, systolic blood pressure decreased by 8%, from 138.9 ± 1.9 to 127.6 ± 3.2 mmHg, and arterial stiffness decreased by 13.5%, with aPWV improving from 12.6 ± 0.3 to 10.9 ± 0.4 m/s. Participants with normal blood pressure and healthy arterial function did not experience measurable changes (5), suggesting that benefits may be more pronounced in individuals with early vascular changes.

    Overall, across multiple small clinical trials, daily spirulina supplementation in the range of 2.0–4.5 grams has been associated with improvements in systolic and diastolic blood pressure, triglycerides, LDL cholesterol, HDL cholesterol, and markers of blood vessel function—particularly in individuals with hypertension or elevated metabolic risk. While these findings are promising, most studies are relatively small and short-term, and larger, longer-duration trials are needed to confirm the long-term benefits and optimal use.

References:

1.     Miczke A, Szulińska M, Hansdorfer-Korzon R, Kręgielska-Narożna M, Suliburska J, Walkowiak J, Bogdański P. Effects of spirulina consumption on body weight, blood pressure, and endothelial function in overweight hypertensive Caucasians: a double-blind, placebo-controlled, randomized trial. Eur Rev Med Pharmacol Sci. 2016;20(1):150-6. PMID: 26813468.

2.     Martínez-Sámano J, Torres-Montes de Oca A, Luqueño-Bocardo OI, Torres-Durán PV, Juárez-Oropeza MA. Spirulina maxima Decreases Endothelial Damage and Oxidative Stress Indicators in Patients with Systemic Arterial Hypertension: Results from Exploratory Controlled Clinical Trial. Mar Drugs. 2018 Dec 8;16(12):496. doi: 10.3390/md16120496. PMID: 30544795; PMCID: PMC6315658.

3.     Ghaem Far Z, Babajafari S, Kojuri J, Mohammadi S, Nouri M, Rostamizadeh P, Rahmani MH, Azadian M, Ashrafi-Dehkordi E, Zareifard A, Golchin Vafa R, Mazloomi SM. Antihypertensive and antihyperlipemic of spirulina (Arthrospira platensis) sauce on patients with hypertension: A randomized triple-blind placebo-controlled clinical trial. Phytother Res. 2021 Nov;35(11):6181-6190. doi: 10.1002/ptr.7254. Epub 2021 Sep 20. PMID: 34542204.

4.    Torres-Duran PV, Ferreira-Hermosillo A, Juarez-Oropeza MA. Antihyperlipemic and antihypertensive effects of Spirulina maxima in an open sample of Mexican population: a preliminary report. Lipids Health Dis. 2007 Nov 26;6:33. doi: 10.1186/1476-511X-6-33. PMID: 18039384; PMCID: PMC2211748.

5.     Virsolvy A, Benmira AM, Allal S, Demattei C, Sutra T, Cristol JP, Jouy N, Richard S, Perez-Martin A. Benefits of Dietary Supplementation with Specific Silicon-Enriched Spirulina on Arterial Function in Healthy Elderly Individuals: A Randomized, Placebo-Controlled Trial. Nutrients. 2025 Feb 28;17(5):864. doi: 10.3390/nu17050864. PMID: 40077730; PMCID: PMC11901655.

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