According to a recent study, spirulina may help to reduce blood pressure. The researchers also identify the active compound that produces this benefit.

As the supplement movement shifts into top gear, researchers are examining a range of nutritional ingredients for their potential health benefits.

Among this ever-growing clan of so-called superfoods is spirulina.

Spirulina is the dried biomass of Spirulina platensis, a species of cyanobacteria, or blue-green algae as they are more commonly known.

Today, this ingredient is widely used as a supplement and added to certain foods, but it has a long history that stretches back to the Aztecs and ancient Africa. Historically, people harvested the bacteria from ponds and lakes and turned them into "cakes."

Because spirulina contains high levels of protein, iron, and other nutrients, it is of interest to researchers investigating food security, malnutrition, and even long-distance space travel.

Spirulina's health benefits

This nutrient-dense product has links with a range of health benefits. For instance, some research has shown it to have anti-inflammatory properties, help control levels of glucose and lipids in the blood, reduce the symptoms of allergic rhinitis, and even protect against some types of cancer.

Although many of these claims lack adequate evidence, research into spirulina's potential health benefits is ongoing. The most recent investigation is available in the journal Hypertension.

The authors, from a number of institutions across Italy, including the Vascular Physiopathology Laboratory of the I.R.C.C.S. Neuromed in Pozzilli, investigated its potential to counteract arterial hypertension.

Scientists have previously noted spirulina's positive influence over blood pressure. In the current study, the scientists wanted to drill down into the details and understand exactly how it interacts with blood vessels to produce this benefit.

First, they simulated the effects of digestion on spirulina, as first author Albino Carrizzo explains:

"[W]e reproduced what happens in the human gut after ingesting the substance. This way we have been able to isolate the peptides that would be absorbed by our body."

Then, the researchers tested the "digested" spirulina on arteries extracted from mice. As they expected, spirulina caused relaxation of the arteries; an effect mediated by nitric oxide (NO).

NO is known to play a vital role in maintaining healthy blood pressure, and for many individuals with hypertension, it is the NO mechanism that is at fault.

Identifying the active ingredient

Next, the team wanted to determine the active molecule in the digested spirulina that was responsible for this activity.

After using what the researchers refer to as a "complex multistep peptidomic approach," they identified one particular peptide that appeared to impart spirulina's antihypertensive prowess—SP6.

SP6 interacts with an important signaling pathway known as PI3K/AKT. This interaction leads to the release of NO and, consequently, a drop in blood pressure.

"We know that hypertensive patients often have a defect in the natural processes that, by the action of NO, regulate endothelium (the inner wall of blood vessels). The peptide we isolated in spirulina extract acts positively on this mechanism."

—Author, Prof. Carmine Vecchione

To further test SP6's antihypertensive powers, they administered it to mice. As theorized, they measured a drop in blood pressure.

Lastly, they investigated SP6 in an animal model of hypertension; once again, they found that it reduced hypertension significantly.

Because this is the first study to identify SP6 as a potential antihypertensive, much more research will be needed. However, the authors are excited by the prospects.

Prof. Vecchione believes that "SP6 could be a natural adjuvant to common pharmacological therapies in order to improve endothelial function and, consequently, combat hypertension."

According to the Centers for Disease Control and Prevention (CDC), hypertension affects almost one-third of adults in the US. Finding a cost-effective, safe, natural compound that helps reduce blood pressure could save money and, more importantly, improve and extend lives.