In the endurance sport community, spirulina has become a trendy addition to the postworkout smoothie for its antioxidant and anti-inflammatory properties. Blue green algae, or “spirulina,” was a common item within the health food industry long before it became a “superfood” for its purported health and nutrition benefits.

Here, we’ll dive into to what spirulina is and whether there’s enough evidence to back up the claims behind algae supplements for cyclists.

What are the nutritional benefits of spirulina?

Spirulina is a cyanobacteria derived from blue green algae and then dried to be used in pill or powder form. (Sometimes spirulina is combined with a plant-based protein powder in small amounts).

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Spirulina supplements claim to be rich in protein and micronutrients—such as potassium, calcium, magnesium, and iron—and boast antioxidant and anti-inflammatory properties, but you would need to take a lot more than the amount being used in research to reap the nutrient benefits.

For reference, 1 tablespoon (or 7 grams) of spirulina is about the amount used in most studies. This small amount of spirulina contains the following:

  • 20 calories
  • 1.7 g carbs
  • 4 g protein
  • 95 mg potassium
  • 74 mg sodium
  • 8.5 mg calcium
  • 14 mg magnesium
  • 2 mg iron

Perhaps overlooked, spirulina is also high in vitamin K and beta carotene.

As with all supplements Tom Gurney, Ph.D., a sport science researcher at Kingston University in London suggests “checking the ingredient label and whether the supplement is independently batch tested for purity and quality.”

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Why is spirulina good for you in general?

The anti-inflammatory properties are primarily associated with phycocyanobilin, the blue-green pigment found in spirulina, which containing antioxidant properties. This rich antioxidant may help decrease inflammation in your body and help with exercise recovery. However, the use of high antioxidant or anti-inflammatory products during the base phase of training use is questionable as it may interfere with training adaptations, according to sports dietitian Namrita Kumar, Ph.D., R.D.N. That’s because, during the base phase of training, the inflammatory response is important for training adaptations to occur. Thus, the use of high antioxidant products may be better utilized during the racing season for rapid recovery purposes.

Can spirulina help with cycling performance specifically?

While initial studies have examined health benefits of spirulina—for instance, reductions in risk for factors for heart disease and improved immunity—more recent work has examined the potential benefits for exercise performance.

A recent study published in the journal Applied Physiology Nutrition and Metabolism examined spirulina supplementation (6 grams per day) for 21 days on various cycling intensities. The study authors found a significantly lower heart rate and blood lactate levels during low intensity cycling sessions after supplementation with spirulina.

“Increases in hemoglobin and improvements in power output were also observed after supplementation with spirulina,” says Gurney, who was the lead author of the study.

While these results seem promising, Gurney cautions it’s important to remember that this area is still very new and in its early stages. However, there may be a potential reason for these observed improvements.

“Although speculative, the high iron content and bioavailability [a measure of how much a substance is able to access your body’s circulation and reach the target area] of spirulina may explain the increases in hemoglobin found in these studies,” he says.

It’s no doubt that hemoglobin—the protein that transports oxygen from the lungs to the muscles during exercise—is important for endurance performance.

“If there are significant changes to hematological markers, such as hemoglobin, supplementation should be advised under supervision by an R.D.N. or physician to ensure safety and avoidance of any interactions or contraindications [situations where a drug or procedure should not be used because it may be harmful to the person],” says Kumar.

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Is there an optimal dosage that provides benefits?

The majority of the studies examining athletic performance have used 6 grams of spirulina per day, and studies examining health benefits have ranged from 2 to 8 grams per day. More research is needed to determine the optimal dosage, how long the supplement should be taken, and timing of delivery of spirulina.

“The trend at the moment seems to suggest that a loading period—rather than taking it quickly before exercise—is required before any benefits are seen,” Gurney says. “However, our previous work demonstrated that loading with 6 grams per day of spirulina for one week was beneficial for arm cranking [in the study]—or upper-body exercise [in general]—while the more recent study used a loading protocol of 6 grams per day of spirulina for three weeks.”

The bottom line

Before you buy into the hype, more research is needed to determine how and whether spirulina improves exercise performance in cyclists.

“While it’s tempting to rely on ‘superfoods’ like spirulina for performance benefits, we don’t really have enough information yet to recommend supplementation,” says Kumar.

However, if you are set on giving spirulina a try in your smoothie bowl, be sure to choose a product that is third-party tested.