Is Spirulina Good for You?

Medically Reviewed by Zilpah Sheikh, MD on May 26, 2024
6 min read

Spirulina is blue-green algae that’s packed with vitamins, minerals, antioxidants, and protein. It has a long history as a superfood. First eaten by the ancient Aztecs for its nutrition, spirulina was used more recently as a supplement for NASA astronauts on space missions. 

Today, research supports many of the potential benefits of spirulina, and researchers continue to study its potential for treating health concerns. Spirulina is available in powder, capsule, and tablet forms, and it’s added to certain protein bars, smoothies, and juices.

Spirulina vs. chlorella

Like spirulina, chlorella is nutrient-rich algae that’s used as a health supplement. But there are some differences: Spirulina has a blue hue, compared to chlorella’s vibrant green color. Chlorella is higher in vitamin A and omega-3 fats, while spirulina contains more protein and vitamins E and K.

One tablespoon of spirulina contains: 

  • Calories: 20
  • Protein: 4 grams
  • Fat: 1 gram
  • Carbohydrates: 2 grams
  • Fiber: 0 grams
  • Sugar: 0 grams

Spirulina is a good source of: 

Spirulina also contains magnesium. This mineral supports normal daily functions like muscle movements and your heartbeat. It’s also responsible for producing protein and creating energy – but most people don’t get enough in their diet. 

Spirulina protein

Spirulina is rich in plant protein. Protein makes up 65% to 70% of its content. Most of this protein comes from phycocyanin, a pigment that gives spirulina its blue-green color.

Spirulina is a rich source of vitamins, minerals, and fatty acids. It’s also high in the plant protein phycocyanin, which has antioxidant and anti-inflammatory properties. 

These nutrients in spirulina are linked to several health benefits:

Anti-cancer properties

Many antioxidants in spirulina have anti-inflammatory effects in the body. Chronic inflammation contributes to cancer and other diseases. 

Phycocyanin has been found to not only reduce inflammation in the body, but also block tumor growth and kill cancer cells. The immune-enhancing protein is being studied for its potential in cancer treatment. 

Heart health

Research has found that the protein in spirulina can reduce your body’s absorption of cholesterol, lowering cholesterol levels. This helps keep your arteries clear, reducing strain on your heart that can lead to heart disease and stroke-causing blood clots

Phycocyanin also reduces triglyceride levels. These are fats in your blood that can contribute to the hardening of arteries, increasing the risk of heart disease, diabetes, and pancreatitis

Spirulina increases nitric oxide production in your body as well, which helps your blood vessels relax. Studies show that this can reduce your blood pressure, lowering your heart disease risk. 

Allergy relief

The anti-inflammatory effect of spirulina’s antioxidants may help you with allergies caused by pollen, animal hair, and dust. One study found that symptoms like congestion, sneezing, and itching were reduced significantly, suggesting that spirulina may be a good alternative to allergy medications. 

Immune system support

Spirulina is rich in a range of vitamins and minerals essential for maintaining a healthy immune system, like vitamins E, C, and B6. Research finds that spirulina also boosts the production of white blood cells and antibodies that fight viruses and bacteria in your body. 

Laboratory studies show that spirulina can fight herpes, the flu, and HIV – though much more research is needed to test these effects in humans. 

Eye and oral health

Spirulina is concentrated with zeaxanthin, a plant pigment that may reduce the risk of cataracts and age-related vision loss. Its antibacterial properties may also help promote good oral health. One study found that spirulina-enhanced mouthwash reduced dental plaque and the risk of gingivitis in the people being studied. Another study showed it lowered the risk of oral cancer in people who chew tobacco. 

Weight loss

Spirulina is a source of protein, which takes longer for your body to digest and can fend off hunger. One study done on people on a low-calorie diet found that those who took a spirulina supplement shed more weight and lost more body fat, compared to those who had a placebo pill. Spirulina may also help you feel fuller and prevent fat buildup in the liver, both of which also encourage weight loss. 

You should always talk to your doctor before taking a supplement. Spirulina may pose health risks:


Spirulina harvested in the wild may be contaminated with heavy metals and bacteria. In high amounts, some of these toxins may stress or damage your liver. 

Pregnancy concerns

There is not enough research to confirm whether blue-green algae is safe for pregnant or breastfeeding women. 

Bleeding disorders

Because spirulina can help reduce blood clotting, it may increase the risk of bruising and bleeding in people with certain bleeding conditions. 


Spirulina might affect blood sugar levels, so people with diabetes should monitor their blood sugar when taking spirulina.

Autoimmune diseases

Research shows that spirulina can support immune system function, but this could worsen symptoms in people with autoimmune diseases like lupus, multiple sclerosis, or arthritis. Talk to your doctor before adding spirulina to your diet if you have an autoimmune condition. 

Medication interactions

Spirulina may interact with or counter the effects of certain medications, including immunosuppressants, blood thinners, and drugs used to treat diabetes.

Spirulina side effects

When taken as directed, spirulina generally doesn’t cause side effects. In some people, it may cause mild side effects, including headaches, diarrhea, bloating, and gas.

Experts recommend taking no more than 8 grams of spirulina a day. That’s a little more than two teaspoons of the blue-green algae. You can use it in the following ways: 

Spirulina powder

Try adding the powder to guacamole, hummus, or pesto. You can also sprinkle it on popcorn and salads, or mix it into energy balls or granola bars. Spirulina has an earthy, fishy flavor that some people may find off-putting. 

Spirulina tablets

If you don’t like the taste of spirulina, a tablet or capsule may work for you.

Adding spirulina to drinks

Spirulina adds nutrients to any smoothie. You can also stir spirulina powder into juice; the sweetness can mask the flavor.

Spirulina is blue-green algae that’s packed with good-for-you nutrients and plant protein, which may improve your health. If you’re interested in using spirulina, talk to your health care provider about what brands and amounts are best for you. A standard dose is 5 grams daily.

What does spirulina do to the body?

Because spirulina is high in nutrients and antioxidants, it may help lower inflammation in the body. It may improve your immune system and heart health, and reduce the risk of several diseases. 

Is spirulina safe to take every day?

Spirulina is considered safe, even in high doses. Experts recommend getting no more than 8 grams per day.

What foods is spirulina found in?

Spirulina is a type of algae. It’s sometimes added to certain foods and beverages, such as smoothies, popcorn, and energy bars.

Is spirulina good for you to lose weight?

Spirulina is low in calories and high in protein, which can help you feel full and fend off hunger. Research suggests that it may encourage weight loss.