An analysis of 29 randomized controlled trials involving 1,583 participants found that eating whole algae was associated with modest reductions in systolic and diastolic blood pressure, with stronger results among people who began with elevated readings and among those consuming spirulina.
By yourNEWS Media Newsroom
Eating whole edible algae such as spirulina, nori and kelp may modestly reduce blood pressure, according to a pooled analysis of 29 randomized controlled trials that examined the effects of algae consumption in 1,583 participants.
Researchers based in the United Kingdom and Spain combined the trial data in an analysis published in the Journal of Human Nutrition and Dietetics in July 2025, according to a report from NaturalHealth365. Across the studies, systolic blood pressure — the upper number in a blood pressure reading — declined by an average of about 2 points, while diastolic pressure fell by nearly 2 points.
The reductions were greater among participants who already had elevated blood pressure when the trials began, the report stated. Spirulina produced the largest reductions among the algae examined, while duration and daily intake also appeared to influence the results.
Algae have been consumed as both food and traditional remedies for centuries. Lisette Kreischer and Marcel Schuttelaar wrote in “Ocean Greens” that algae have been used medicinally in China and Japan for hundreds of years. Previous reporting has also associated seaweed consumption with lower blood pressure.
Unlike research centered on isolated compounds derived from algae, the trials included in the analysis primarily examined algae consumed as whole foods or powders. Researchers compared changes in blood pressure among adults consuming the algae with those in control groups that did not.
The individual trials varied in the type of algae provided and the amount participants consumed. Among the foods evaluated were nori, kelp and spirulina, representing a broader category of edible algae that includes multiple nutritional profiles.
Seaweeds are commonly grouped according to characteristics such as pigmentation and structure, with green, brown and red algae among the major categories, according to NaturalNews.com.
Their nutritional composition varies considerably by species. Kelp provides iodine, potassium and sodium, according to Adriane Fugh-Berman in “The 5-minute herb and dietary supplement consult.” Susannah Blake wrote in “Natural superfoods” that whole edible seaweed can also provide calcium, vitamin C, iodine and antioxidants.
Those nutrients and other naturally occurring compounds are among several possible explanations researchers have considered for algae’s observed relationship with blood pressure.
The overall reductions across the 29 trials were modest, but the results differed substantially depending on the algae consumed. Participants receiving spirulina experienced a decline of more than 5 points in systolic pressure and nearly 4 points in diastolic pressure, according to the report.
The report described the magnitude of the spirulina findings as comparable to the effects of some blood pressure medications in mild cases. Previous research has separately associated spirulina consumption with lower blood pressure, according to NaturalNews.com.
Researchers also identified a pattern involving the amount consumed and how long participants continued taking it. The clearest results occurred in studies in which participants consumed more than 3 grams of algae per day for at least 12 weeks.
Whole algae also consistently performed better than algae extracts in the trials, according to the report. That difference led researchers to suggest that the observed effects may depend on multiple substances naturally present together in the food rather than a single extracted ingredient.
Several potential mechanisms could be involved.
Edible algae contain compounds including potassium, peptides, antioxidant pigments and naturally occurring nitrates. Nori and kelp, for example, contain nitrates similar to those present in leafy green vegetables.
Dietary nitrate can be converted in the body into nitric oxide, which helps blood vessels relax and widen and may consequently lower blood pressure. A NaturalNews.com analysis described that pathway as one reason nitrate-rich leafy greens may support healthier blood pressure. Separate reporting has linked spinach with lower blood pressure through several nutritional mechanisms.
Spirulina contains phycocyanin, the blue pigment responsible for much of its distinctive color. The NaturalHealth365 report said phycocyanin may contribute to relaxation of the blood vessels.
Chlorophyll, another naturally occurring pigment, is found in green foods including spirulina, chlorella and kelp and has also been discussed in natural health literature.
Rather than attributing the results to any single nutrient, the authors hypothesized that several components of whole algae may work together. Their proposed mechanisms include promoting relaxation of blood vessels while also supporting the kidneys as they regulate sodium.
The relationship between sodium and potassium is closely tied to blood pressure regulation. J Housley wrote in “The Encyclopedia of Nutrition and Good Health” that the hormone aldosterone directs the kidneys to conserve sodium while releasing potassium.
The finding that whole algae appeared more effective than isolated extracts is consistent with the possibility that interactions among minerals, pigments, peptides, nitrates and other constituents may be relevant to the observed blood pressure changes.
The report also described simple ways to incorporate edible algae into meals without substantially changing a person’s diet.
Spirulina powder can be added to smoothies, while dried nori sheets can be eaten on their own or crumbled over foods such as salads and rice. Smoothies can also be customized with other nutrient-dense ingredients according to an individual’s nutritional and fitness goals, NaturalNews.com has reported.
Another approach described in the report was combining algae with other nitrate-containing vegetables, including beets, spinach and arugula. Such combinations would introduce several foods associated with pathways that support blood flow rather than relying exclusively on one dietary ingredient.
For people interested in determining whether a dietary change corresponds with changes in their own blood pressure, the report recommended taking home measurements at approximately the same time each day and tracking them for 12 weeks. That period reflects the duration associated with some of the clearest findings in the trials.
The results do not mean edible algae should be treated as a substitute for prescribed hypertension medication. Individuals already taking blood pressure drugs were advised to consult a clinician before making dietary changes that could affect their treatment or blood pressure readings.
The findings also fit within a larger body of research examining dietary patterns rather than individual foods. The Dietary Approaches to Stop Hypertension, or DASH, diet, which emphasizes whole foods, has repeatedly been shown to reduce blood pressure.
Taken together, the 29 trials found an association between whole edible algae consumption and reductions in both systolic and diastolic pressure. The effects were most pronounced among participants who began with elevated blood pressure, in the spirulina subgroup and in studies using more than 3 grams of algae daily for at least 12 weeks.
The stronger results for whole algae compared with extracts also led researchers to focus on the possibility that several naturally occurring constituents work together, rather than identifying a single compound as responsible for the effect. The report recommended viewing algae as one component of a broader whole-food dietary pattern while continuing appropriate medical treatment and monitoring blood pressure over time.
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