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Dec 18, 2023

Spirulina: Health Benefits, Uses and Risks

Wendy Wisner is freelance journalist and international board certified lactation

Wendy Wisner is freelance journalist and international board certified lactation consultant (IBCLC). She has written about all things pregnancy, maternal/child health, parenting, and general health and wellness.

Aniko Hobel / Getty Images

Spirulina is a blue-green algae that grows naturally in saltwater lakes and oceans and is rich in protein, vitamins, minerals, carotenoids, and antioxidants that can help protect cells from damage. The Aztecs in Mexico and people in the Lake Chad area of Africa have used spirulina for centuries. But spirulina didn't become popular in the U.S. until the 1970s. Today, you can buy spirulina in pill or powder form.

Researchers are still exploring the health benefits of spirulina but there is evidence that it can help with conditions like high blood pressure and high cholesterol. Read on to learn more about the health benefits and nutritional profile of spirulina as well as information about its safety and dosage.

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Spirulina is a nutrient-packed food containing a surprising variety of vitamins, minerals, amino acids, coenzymes, and antioxidants. It's a good sources of protein and provides essential amino acids.

Spirulina contains high amounts of antioxidants like beta-carotene and vitamin E and minerals like magnesium, zinc, copper, selenium, and iron. Spirulina is also a good source of both omega-6 and omega-3 fatty acids.

There is some early evidence that spirulina may protect against cancer. A 2021 systematic review found that blue-green cyanobacteria like spirulina act as anticancer agents in the body. In other words, spirulina may have the ability to slow or stop the growth of cancer cells.

Substances in blue-green algae have antioxidant and antimetastatic (cancer-spreading) qualities. There are also indications that blue-green algae could work well with other cancer-fighting drugs. However, it's important to note that this research does not mean that taking spirulina supplements you buy online or from a health foods store will stop or prevent cancer.

Spirulina is a powerful antioxidant that has anti-inflammatory and immune-boosting qualities. Supplementing with spirulina may boost the efficiency of your immune system, potentially stimulating your natural killer cells (a type of white blood cell that destroys infected or cancerous cells). Additionally, spirulina may improve your gut health and has probiotic qualities, which may have an antioxidant effect by neutralizing free radicals (unstable atoms that can damage cells, causing illness and aging.

There's good evidence that spirulina can help regulate blood pressure and manage hypertension. One study looked at people diagnosed with hypertension and found that those who took 4.5 grams of spirulina daily for six weeks saw decreases in blood pressure. Another study found that supplementing with 2 grams (g) of spirulina for twelve weeks decreased systolic blood pressure by 7 mmHG, and diastolic blood pressure by 6 mmHG.

There is promising data that says that supplementing with spirulina can decrease cholesterol levels and help with overall metabolic health. A 2013 study looked at people with newly elevated cholesterol levels. The study found that supplementing with 1 g of spirulina daily for three months decreased triglyceride levels and lowered total cholesterol levels. A meta-analysis from 2019 also found that supplementing with spirulina reduced total cholesterol levels.

There is some evidence that spirulina can help with the symptoms of allergic rhinitis (allergy symptoms in the nose, also known as hay fever). A small study from 2020 found that spirulina was more effective at reducing allergic rhinitis symptoms than the allergy medication cetirizine (Zyrtec). Though more research is needed, the results of this study may have promising implications.

Spirulina is a good source of iron, and it's been speculated that it might help people with anemia. Anemia is a condition characterized by a reduction in hemoglobin or red blood cells in your blood. Without enough iron, your body can't produce enough of a substance in red blood cells that enables them to carry oxygen (hemoglobin) to your body's tissue and organs.

A small study found that among people 50 or older, supplementing with spirulina for twelve weeks had positive effects on their hemoglobin counts, especially in women. However, more recent research is needed to draw conclusive findings.

People with diabetes or who are at risk of developing diabetes are often looking for ways to keep their blood sugar in check.

A systematic review from 2021 found that spirulina supplementation in doses ranging from 0.8-8 g daily can improve fasting blood sugar levels as well lipid profiles in people with type 2 diabetes. Still, more studies are needed to draw conclusive findings.

Spirulina is a good source of protein, especially for vegans or those who avoid animal byproducts. Although spirulina doesn't have as much protein as milk and meat sources, at 4 g of protein per tablespoon, it has more protein than many plant-based protein sources.

A small 2014 study found that supplementing with spirulina may help people who have non-alcoholic fatty liver disease (NAFLD). Those studied took a high dose of spirulina (6 g) daily for six months. At the end of the trial period, there were significant reductions in liver enzyme levels, triglycerides, total cholesterol, low-density lipoprotein-cholesterol, and total cholesterol/high-density lipoprotein cholesterol ratios. All of these reductions indicate a more healthy functioning liver.

Spirulina may be beneficial for people with obesity. A 2019 systemic review found that spirulina may reduce body fat percent and waist circumference in people who carry more weight. However, this meta-analysis only included five studies, so more studies are needed to draw conclusions about how spirulina may help with weight loss.

There are some indications that spirulina can help your oral health. A 2013 study found that spirulina gel applied to the gums can help with symptoms of periodontitis (gum disease). There is also evidence that spirulina can fight oral submucous fibrosis (OSMF), a condition that can lead to cancerous lesions in the mouth. However, more studies are needed.

According to the USDA, one tablespoon of spirulina provides:

Spirulina contains minimal sugar, and is rich in vitamins and minerals such as folate, choline, vitamin A, and beta-carotene.

Spirulina is a food and is considered low risk for most people to consume in moderate quantities. The FDA doesn't regulate food supplements, but categorizes spirulina as "generally recognized as safe." When possible, choose a spirulina supplement that has been tested by a trusted third party, such as ConsumerLabs, USP, or NSF.

Spirulina may be contaminated with toxins if it grows in bodies of water that are polluted with heavy metals, bacteria, or microcystins, a type of bacteria produced by blue-algae to protect it against predators.

Adverse effects like cramping, bloating, gassiness, diarrhea, dizziness, and vomiting can occur. Allergic reactions such as rashes and hives are also possible. If you experience any negative effects after using spirulina, stop consuming it and contact your healthcare provider.

Spirulina is sold either in pill form (capsules) or as a fine, green powder that you can add to your food. Spirulina is savory and has a vague seafood-like flavor which can be offset with fruit or other sweeteners. Many enjoy the flavor on its own.

There are many uses for spirulina in powder form, including:

Experts agree that children and pregnant or lactating people should not consume spirulina. Additionally, people with autoimmune diseases like lupus, multiple sclerosis, or rheumatoid arthritis should not consume spirulina as it may stimulate your immune system and make your condition worse.

If you are just starting to consume spirulina, you should start with a low dose and work your way up to avoid unpleasant side effects such as gassiness, bloating, or diarrhea.

People have taken up to 10 grams daily for up to six months without any issues.

Spirulina shouldn't be taken alongside certain medications, including:

Talk to your healthcare provider if you are taking any herbal supplements, especially ones that lower blood sugar or slow blood clotting, as these may be dangerous to mix with spirulina. Spirulina contains about 0.26 micrograms (mcg) of vitamin K in each gram, and anything more than that could enhance the blood-thinning effect of some medicines.

Spirulina is a nutrient-rich blue-green algae that has been consumed for decades. It has antioxidant qualities and may help to help reduce blood pressure, decrease high cholesterol, regulate blood sugar, and help boost oral health. However, it should not be used as a substitute for medical care. Be sure to speak to your healthcare provider before you introduce a new supplement to your daily routine.

It's not clear whether taking spirulina blocks B12 absorption. However, the type of B12 found in spirulina is not found naturally in the human body , and may not be helpful for people looking to raise their B12 levels.

Both spirulina and chlorella are nutrient-rich forms of algae but they are not the same organism. Chlorella is higher in calories and fat than spirulina. Unlike spirulina, chlorella contains vitamin D2.

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