8 Health Benefits of Spirulina—And When You Should Avoid It

Spirulina is a nutrient-packed blue-green algae typically found in powdered form. This superfood is full of health benefits and is often used in a variety of green dishes, from smoothie bowls to guacamole and even pesto. Known for its protein-rich content, spirulina offers vital nutrients and properties we need from our food. Here's everything you need to know about this superfood and how to easily add it to your diet.

What Is Spirulina, and Where Does It Come From?

Spirulina, scientifically known as Arthrospira, is a type of algae that has been used as a food source and for medicinal purposes for centuries. For instance, the Aztecs in Mexico utilized spirulina both for nourishment and to treat various health conditions. Today, spirulina continues to be used in similar ways, even serving as a dietary supplement for astronauts on NASA missions.

The demand for spirulina is rapidly increasing as people around the world seek out this nutrient-rich freshwater plant. Research from KBV Research estimates the global spirulina market will reach $651 million by 2025. While spirulina naturally grows in alkaline lakes, companies are now cultivating these algae in controlled environments, such as large tubes, to meet the growing demand. Spirulina has a distinctive, earthy flavor reminiscent of seaweed.

Spirulina's Nutritional Benefits

Emmie Satrazemis, RD, advocates for the inclusion of spirulina in a balanced diet. She emphasizes that this plant-based food is nutrient-dense. Below are several health benefits of spirulina that make it a standout superfood.

1. Spirulina is an excellent source of plant-based protein.

Satrazemis describes spirulina as a food that is "protein-dense and low-calorie." A single tablespoon of spirulina contains just 25 calories, 0.5 grams of fat, 1 gram of carbohydrates, and 4 grams of protein, making it a highly protein-packed food.

2. Spirulina is a rich source of essential vitamins and minerals.

"It contains significant amounts of calcium, niacin, potassium, magnesium, B vitamins, and iron," Satrazemis notes. Spirulina is especially rich in vitamin B12, which plays an important role in DNA formation and supports the health of blood and nerve cells. Additionally, it is an excellent source of iron, offering about 2 grams per tablespoon.

3. Spirulina is packed with plant compounds that promote eye health.

"Spirulina is also a significant source of phytonutrients—plant-based compounds (specifically plant pigments) believed to have protective health properties," Satrazemis explains. More specifically, spirulina is rich in carotenoids, a group of phytonutrients that benefit both eye and immune health. According to a 2020 research review, carotenoids like lutein and zeaxanthin, which are found in the retina, may reduce the risk of macular degeneration.

4. Spirulina provides essential fatty acids.

Although spirulina is generally low in fat, it serves as a plant-based source of omega-3 and omega-6 fatty acids, including gamma linoleic and oleic acid. Research shows that omega-3 fatty acids may help combat depression and anxiety, protect the brain from cognitive decline due to aging, and support brain health during pregnancy and early development. In addition to benefiting the brain, omega-3 fatty acids may also improve heart disease risk factors, reduce inflammation, and enhance bone and joint health.

5. Spirulina is rich in antioxidant plant compounds that combat inflammation.

Spirulina contains a high concentration of bioactive plant compounds, such as polyphenols and plant pigments, which offer significant antioxidant and anti-inflammatory benefits. These compounds help protect the body’s cells from damage caused by free radicals and oxidative stress, factors that can contribute to inflammation and various diseases.

6. Spirulina may help foster the growth of beneficial gut bacteria.

Earlier in vitro research and animal studies suggest that this aquatic plant may play a role in supporting gut health by promoting the growth of probiotics (beneficial gut bacteria).

7. Spirulina could alleviate symptoms linked to chronic disease.

Although some studies have been limited to animal models, spirulina has shown potential in reducing the size of cancerous tumors, thereby lowering the risk of symptoms associated with chronic diseases.

8. Spirulina can help lower blood pressure and improve hypertension.

Research indicates that consuming 1-8 grams of spirulina daily can lead to a reduction in both systolic and diastolic blood pressure, thereby improving hypertension. It is believed that spirulina boosts nitric oxide production, which aids in dilating and relaxing blood vessels.

Spirulina: Potential Side Effects, Safety Concerns, and When to Avoid It

"Spirulina acts as a blood thinner, so if you suffer from any clotting disorders, it's crucial to consult your healthcare provider before incorporating spirulina into your diet," warns Christina Manian, RDN.

Manian also mentions that spirulina contains a high amount of phenylalanine, an amino acid that should be avoided by individuals with phenylketonuria (PKU), a rare genetic disorder where the body cannot break down phenylalanine.

"Like other algae, spirulina is highly sensitive to its growing environment," explains Manian. "While this allows it to absorb beneficial nutrients, it also means it can take in harmful substances like heavy metals and toxins from the environment."

Due to its ability to absorb heavy metals and toxins, spirulina may not be the best choice for pregnant individuals. "Pregnant women should be extra cautious when selecting a spirulina source, and I recommend speaking with a healthcare provider before making any purchases," advises Manian.

To avoid harmful additives, the best approach is to select a spirulina supplement from a brand that has undergone third-party testing for purity standards, especially since these products are not regulated or tested by the U.S. Food and Drug Administration.

Where to Purchase Spirulina and How to Store It

Spirulina is offered in various forms, such as capsules, powders, and is even incorporated into other foods like bars, smoothies, or sprinkled on top of popcorn. It’s available year-round in grocery stores worldwide.

To preserve its quality, spirulina tablets and powder should be stored in the refrigerator. While it doesn't exactly spoil, its nutritional benefits diminish over time, so it's ideal to consume it within a few months after opening.

Creative Ways to Add More Spirulina to Your Diet

As you might expect, spirulina can be added to nearly any dish to boost its nutritional value. Here are a few of our favorite ways to enjoy it.

• Mix it into your favorite smoothie recipe.
• Enhance chia pudding by adding spirulina for an even more nutritious sweet treat. It helps balance out any excess sugar and turns an easy dessert into your go-to snack. Just sprinkle it in with the chia seeds!
• Add a pinch of spirulina to these chickpea "cookie dough" bites for a touch of earthy flavor to complement the chickpeas.
• Sprinkle spirulina over a salad or blend it into your salad dressing.

Frequently Asked Questions

• How much spirulina should you consume per day?

  "There’s no official recommendation for how much spirulina you should consume per day. However, a generally accepted dose from the research we have thus far is somewhere between 1 and 3 grams, and up to 10 grams per day,” Manian says. “A great rule of thumb is to enjoy a tablespoon of spirulina in a smoothie a few times per week.”

• What does spirulina taste like?

  According to Manian, spirulina has a unique flavor best described as a mix of "seawater, lake water, and sulfur with a hint of earthiness. I personally don’t love the flavor, which is why I add it to smoothies," she says, "you can barely tell it’s there!"

• Should you take spirulina in the morning or at night?

  "While there’s no caffeine in spirulina, the protein and B vitamins in particular may [energize you], which [makes it] a great way to start the day, but could potentially interfere with a good night’s sleep," Manian says. "However, spirulina may not have that effect on some people, so I recommend experimenting and seeing what works best for you."

• Is spirulina safe during pregnancy?

  "Because of the potential for spirulina to absorb heavy metals and environmental toxins, I would recommend pregnant women speak with their healthcare provider and be especially diligent researching the source of spirulina they’d like to purchase," Manian says.