What Is Spirulina and Why Is It So Good for You? (2025)

Spirulina, a type of algae, has been lauded for centuries for its high nutritional value, being called, among other things, one of the “most nutrient-dense foods.” Believed to have first been used in ancient Aztec civilizations, spirulina hasmore recentlybeen used as a dietary supplement for NASA astronauts on space missions.

What is spirulina?

Spirulina comes from a blue-green algae plant found in oceans and salty lakes. It’s typically sold as a powder, capsule or tablet supplement. Spirulina is rich with good-for-you nutrients, like:

• Iron
• Beta-carotene
• Thiamine (vitamin B1)
• Riboflavin (vitamin B2)
• Niacin (vitamin B3)
• Copper
• Magnesium

One tablespoon of spirulina includes:

• 20 calories
• 1 gram of fat
• 2 grams of carbs
• 4 grams of protein

“Spirulina is considered one of the oldest plants on Earth,” says registered dietitian Beth Czerwony, RD, LD. “It’s been used by people for a very long time and has been shown to have some very exciting health benefits.”

You may have also heard of blue spirulina. Blue spirulina benefits are the same as spirulina but include a higher concentration of phycocyanin, an antioxidant that gives the algae its bright hue.

Spirulina benefits

There is agrowing body of researchsupporting spirulina’s positive effects on people. Even more benefits have been shown in lab studies that may translate to humans. Czerwony says the evidence so far points to several reasons to be excited about spirulina’s health benefits.

1. It’s a powerful antioxidant

People are always raving about theantioxidanteffects ofblueberries, avocados, salmon and more. You can add spirulina to that list.

“Antioxidants have this wonderful ability to go in and beat up onfree radicals, which are essentially poisons that we come into contact within our everyday lives,” Czerwony explains. “Antioxidants reduceinflammationin our bodies, which can decrease the chances of a whole host of diseases.”

Spirulina’s antioxidative properties are among the reasons it’s used by astronauts. (Interestingly, inflammation has beenshownto be a major health risk of space life.)

2. It’s good for your heart

Spirulina’s anti-inflammatory properties have been shown to have some impressive benefits for your heart. A meta-analysis shows that spirulina may improve blood cholesterolandtriglycerides.

“When we think about anti-inflammatory foods, we’re always thinking about heart health because we know that inflammation can lead to plaque formation andhardening of the arteries,” Czerwony says. “So, if you already havehigh cholesterol, there’s some promise that spirulina is going to help. It could also potentially be used proactively if you’re at risk for heart disease.”

Additional research shows that spirulina may also help reduce and prevent high blood pressure.

3. It may help relieve your seasonal allergies

If you’re allergic to pollen, ragweed, animals and more,researchhas shown that regular use of spirulina may help relieve your runny nose.

“This is a really interesting finding becauseseasonal allergiesare quite common, and some people don’t tolerate allergy medications well or would just prefer a more holistic option to control their symptoms,” Czerwony notes.

4. It may improve your dental health

Spirulina is antimicrobial and antibacterial (meaning it can kill off — or at least stop the growth of — bacteria and other invaders).

One studyput its germ-killing power to the test with spirulina-laced mouthwash. Results showed people who swished with spirulina showed “significant reduction indental plaqueandgingivitis(gum disease).”

5. It may improve your workouts

There’s also research around how spirulina — and its ability to reduce oxidative stress — may play a role in improving muscle strength and endurance. Another study shows that the algae may improve oxygen uptake (also known as VO2).

“Human studies have shown improvement in immunity and brain health by increasing the production of antibodies that can help ward off infection and chronic diseases,” says Czerwony.

6. It may aid in weight loss

A meta-analysis of four studies shows that spirulina may aid in weight loss and reduce body mass index (BMI).

“The human studies were in conjunction with a reduced calorie intake and exercise, so it may be that spirulina has appetite suppressing abilities or it was the diet/exercise independently causing the weight loss,” explains Czerwony. “The studies are relatively small, so results should be cautiously reviewed and would warrant the need for a larger sample size.”

Spirulina side effects and risks

The U.S. Food and Drug Administration (FDA) doesn’t approve (regulate) supplements. But it does regard spirulina as “generally recognized as safe.”

If you’re looking to add spirulina to your life, you’ll want to go easy on it. It’s recommended to take no more than 8 grams of spirulina per day — that’s a little more than two teaspoons. You may experience some mild side effects like:

• Headaches
• Bloating
• Gas
• Diarrhea

But for all its promising effects, spirulina may not be a good choice for everyone, Czerwony cautions. You should talk with a healthcare provider, like your general practitioner or a nutritionist, before taking spirulina.

That’s because there are some people who should avoid spirulina or at least be wary of it. That includes people who:

• Are pregnant or breastfeeding
• Have a compromised immune system
• Have diabetes
• Have ablood disorder
• Are allergic toshellfishor other seafood
• Have an intolerance to iodine
• Are living withphenylketonuria (PKU)— a rare genetic condition where you have a buildup of the amino acid phenylalanine

Uses of spirulina

Spirulina powdercan be added to your favoritesmoothie, or you can try sprinkling it in yourguacamole, hummus or pesto. The FDA also approvesthe use of spirulina as a colorant and to be used in foods like cereals and beverage mixes.

But some people are put off by the taste of spirulina, even in small amounts. Remember, it’s a sea plant, so the taste can be described as earthy or fishy, which may not be for everyone.

If the taste of spirulina isn’t your jam, Czerwony suggests talking with a healthcare provider about over-the-counter spirulina supplements instead.

“Whole foods are always the preferred source of nutrients,” she adds. “But if you can’t tolerate the taste of it, the capsule form is a good alternative.”

Bottom line?

When you consider the potential benefits of spirulina, you can see why many consider it a “superfood.”

While the research is promising, Czerwony stresses that more human studies are needed to confirm spirulina’s advantages. Lab studies have also considered how spirulina may:

• Improve eye health
• Improve immune health
• Improve gut health
• Support brain health
• Fight against anemia
• Reduce cancerous tumors

“Focusing on a healthy, well-balanced diet should be the first step to improve your health and decrease getting or increasing the progression of chronic disease,” concludes Czerwony. “A ‘food first’ approach is much more effective and someone should not rely on supplementation alone.”