Spirulina is blue-green algae often sold as a dark green powder. This article takes an extensive look at the pros and cons of spirulina.

Also see: Benefits of Spirulina for Weight Loss, Nori Seaweed Benefits, Chlorella Benefits, and Bladderwrack Benefits!

Pros and Cons of Spirulina:

Spirulina a popular superfood best known for its rich nutrient profile, including antioxidants, minerals, and vitamins that have been shown to promote various aspects of health. 

That being said, spirulina may contain some downsides, such as heavy metals and damaging toxins.

Organic spirulina powder with a wooden scoop


1.   It can lower LDL cholesterol and triglycerides

High LDL cholesterol and triglycerides can contribute to the hardening and thickening of the arterial wall, increasing your risk of heart attack, stroke, and heart disease.

High triglyceride levels may also cause inflammation, which is the first step in disease formation.

In one study, consuming 2 grams of spirulina daily significantly decreased bad cholesterol (LDL) and triglycerides while increasing good cholesterol (HDL).

In a similar study, consuming a gram of spirulina daily decreased triglycerides and LDL by 10.1 percent and 13.3 percent, respectively.

2.   It may lower high blood pressure

If not controlled, sustained high blood pressure may lead to complications such as stroke, heart attack, heart disease, and kidney disease, among others.

Dietary supplements such as spirulina may help keep your pressure levels within normal. Spirulina has been shown to increase nitric oxide production by the endothelium. Nitric oxide induces relaxation and dilatation of blood vessel walls causing blood to flow more freely.

3.   Prevents LDL cholesterol oxidation

Oxidized LDL is a potentially harmful type of cholesterol produced when LDL interacts with free radicals in the body. The oxidized LDL becomes more reactive to the surrounding tissues, causing inflammation, leading to various health issues, including cardiovascular conditions.

Along with a healthy diet, daily intake of spirulina may help reduce oxidative damage while increasing antioxidant enzymes in the blood.

4.   It may protect against cancer

According to research, spirulina may activate specific immune cells that fight cancer cells, especially oral cancer.

Animal studies also show that spirulina may activate natural killer cells, which offer defense against the tumor.

5.   It’s high in antioxidants

Antioxidants play an essential role in neutralizing free radicals in the body that might cause oxidation leading to cell damage and disease formation.

Spirulina is an incredible source of antioxidants and may help counteract the effects of free radicals.

It’s rich in phycocyanin, a type of antioxidant that gives spirulina its blue-green color. Studies show that phycocyanin can prevent oxidative stress, fight inflammation, and offer neuroprotective benefits.

Green smoothie with spirulina, spinach and blueberries

6.   It may improve symptoms of allergic rhinitis

Allergic rhinitis is the inflammation of nasal mucosa caused by an allergen such as dust, pollen, flakes of skin from certain animals, and mold. It’s often characterized by sneezing, itchy nose, congestion, runny nose, and watery eyes.

Spirulina is a common natural remedy for allergic rhinitis. Daily consumption of 2 grams may significantly relieve the symptoms, including sneezing, itching, congestion, and nasal discharge.

7.   It may improve blood sugar regulation

Researchers believe spirulina may be very effective in controlling glucose levels in diabetes.

In one study, individuals with type 2 diabetes were put on 2 grams of spirulina every day for 2 months. By the end of the study, they recorded lower fasting glucose levels and postprandial glucose levels than the placebo.

This shows spirulina may be an effective supplement in managing type 2 diabetes and the prevention of complications. 

8.   It may improve anemia

Anemia occurs when you have a low number of red blood cells or lack enough healthy red blood cells circulating in the blood.

Red blood cells carry oxygen throughout the body, and in the presence of anemia, there is less oxygen supply than the cells need to function correctly. This results in symptoms such as fatigue and shortness of breath.

Research shows that 1 tablespoon of spirulina may offer up to 11 percent of your daily iron requirements. In addition to other iron-rich foods, spirulina may help boost your iron intake resolve anemia.


While spirulina is considerably safe and has many benefits, there are potential dangers to keep in mind.

1.   Contamination

Water in the sea can be contaminated with heavy metals such as mercury and lead. Spirulina is an algae that grows in the water, and the chances of it absorbing the metals are high.

Contaminated spirulina may result in health issues such as nausea and vomiting, stomach pain, weakness, thirst, rapid heartbeat, liver damage, shock, and even death.

2.   High levels of iodine

Iodine is essential for proper thyroid function. And since it’s naturally present in water. Spirulina contains high levels of it. However, too much of it can be harmful.

You only need about 150 micrograms of iodine daily, while a quarter once of spirulina contains up to 4500 micrograms, which is too high. In fact, you should not exceed 1100 micrograms in a day.

Too much iodine may cause your thyroid to under-perform or over-perform. It can also increase your risk of thyroid cancer.

3.   Safety concerns

There is limited research on the safety of spirulina in children and pregnant women, and thus should be avoided.

Also, if you have any underlying condition like an autoimmune disease or if you’re taking any medication, consult with your doctor to rule out any possible drug interactions.

The quality of the spirulina you purchase determines whether you’ll be affected by some of these side effects or not. So, be sure to buy from a reputable seller and always go for the blue-green algae free from contamination.

Final Thoughts

Spirulina is a popular dietary supplement with various health benefits, including lowering cholesterol and triglycerides, reducing cholesterol, lowering high blood pressure, preventing LDL oxidation, protecting against cancer, improving anemia, treating allergic rhinitis, and promoting blood sugar regulation.

Nonetheless, spirulina may contain a few potential side effects, such as metal contamination and high iodine levels. So ensure you buy from a reputable dealer.

Also, spirulina may not be safe for pregnant women or children. Likewise, you should avoid it if you have any underlying health problems like autoimmune conditions.

And if taking any medications, consult your doctor to rule out any possible drug interactions.

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