Spirulina is one of the world’s most popular supplements; touted as being a detoxifier, a reliable source of protein for vegans and vegetarians and a source of B12.
But is any of this true? This review will examine these claims and get to the bottom of it all and answer the questions, “Can spirulina or blue spirulina have any role in a healthy diet and health promotion?”
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What is spirulina?
Back in the 1970s, food scarcity and famine were becoming an international crisis and protein was the macronutrient of concern. Many countries in Africa faced frank malnutrition including vitamins and minerals but a lot of work and effort was on addressing protein deficiencies.
Soy was seen as an easy crop to adopt to address protein inadequacy but alternative sources were being researched as well, including spirulina and other algae.
Spirulina is not a single organism but refers to the supplement made from two species of blue-green algae or cyanobacterium, Arthrospira platensis and Arthrospira maxima (1, 2). Cyanobacteria, also called blue-green algae, are microscopic organisms found naturally in all types of water. These single-celled organisms live in fresh, brackish (combined salt and freshwater), and marine water.
The algae has been harvested and dried into cakes and eaten for years by various cultures around the world (3). As a dried food product, it’s nutritious and has been used as a food by people and to enrich livestock feed (3, 4).
In 1974, the World Health Organization declared it the “best food for the future” to combat malnutrition, especially in children (3).
What is blue spirulina?
Surprisingly, blue spirulina is nothing more than regular spirulina that’s had its distinctive deep blue pigment extracted and isolated. The blue pigment in question is called phycocyanin; it’s what’s derived from spirulina and gives it its gorgeous, almost cobalt blue colour. Unlike regular spirulina which some say has a fishy taste, the blue version doesn’t but it still has all the same nutrients.
What’s in spirulina that’s of interest?
Phycocyanin comes from the Greek phyco, meaning algae, and cyanin, meaning blue-green, or aqua colour. This blue pigment is present in blue-green algae but is masked by the chlorophyll that’s present.
By far, the most important compound of interest in spirulina and blue spirulina are phycocyanins including C-phycocyanin. Like many similar phytonutrients, phycocyanin is a potent antioxidant and anti-inflammatory molecule (5).
Spirulina, green or blue, has impressive amounts of other bioactive compounds and phytonutrients. These include phenols, flavonoids, and specialized polysaccharides (a type of carbohydrate). Like other plant foods rich in phenols and flavonoids like cacao and cocoa, olive oil, green tea, berries, etc, spirulina owes its antioxidant and anti-inflammatory properties to these well-research phytonutrients (5).
And like mushrooms, the polysaccharides in spirulina are responsible for its immune-modulating and immune-enhancing effects (5).
13 health benefits of spirulina
High in nutrients
Spirulina typically comes as a powder or tablets. As a rough guideline, 1 Tbsp of powder is about 7 g and 1 tsp about 2-2.3 g. Most tablets range from 500 mg to 1000 mg (1g) per tablet. Therefore, it would take four, 500 mg tablets to equal 1 tsp of powder.
1 tsp (2 g) of spirulina powder has (6):
- 5 calories
- 1 g protein
- 1 g carb
- 0 g fat
- 1 mg iron
- 30 mg potassium
- 20 mg phosphorus
- 0.1 mg vitamin B1
- 4 mg magnesium
- 2 mcg folate
- 0 mcg vitamin B12
Despite what you’ll find on the internet, spirulina IS NOT one of the most nutritious foods on the plant. You’ll read that it’s rich in protein, has a good ratio of omega-6 to omega-3 fats or claims like “gram for gram, spirulina may be the single most nutritious food on the planet”. One look at the nutrient breakdown and you’ll see that’s simply not true.
Many will report the nutrient content of spirulina on a 100 g basis (e.g. “100 g of spirulina powder has 50 g of protein”) BUT, no one is consuming spirulina in that kind of quantity. 100 g (3.5 ounces) would be 14 Tbsp or just shy of one cup. Yes, on a gram for gram basis it sounds impressive but when you look at the typical, safe serving size of 1 tsp, it’s just isn’t as advertised.
Not a reliable source of vitamin B12
It’s often claimed that spirulina contains vitamin B12, but this is false. It has pseudo vitamin B12, inactive compounds called corrinoids, one of which has a structure that’s similar to vitamin B12 BUT which has not been shown to be effective in humans (7, 8, 9, 10). In short, even though it looks like B12, corrinoids have no biological activity and can’t be used or seen as a substitute for B12.
This is a very significant, potential public health problem as forums, blogs, vegan and vegetarian websites and self-stylized health ‘coaches’ promote spirulina as a source of B12 for vegans and vegetarians who, already may have a challenge finding plant-based food sources of vitamin B12. A deficiency can lead to anemia, psychiatric disorders and neurological problems (11).
Has powerful antioxidant and anti-inflammatory properties
Antioxidant science has been around for decades. Essentially, oxidation is the process by various biochemical reactions that are a part of living produce compounds that can damage your cells and tissues including vital protein structures, your cell membranes, and even your DNA.
Your body produces about 90% of the antioxidants you’ll ever need on its own using nutrients from your as building blocks. But some of the antioxidants we need for health come from food (vitamins C, E, beta carotene, phytonutrients, etc).
Damaged cells and tissues leading to inflammation which can aggravate existing chronic conditions. On the other hand, inflammation and oxidation can increase the risk of developing chronic diseases including cancer (12). Sadly, it’s a vicious cycle: inflammation drives more oxidation, and, in turn, oxidation leads to more inflammation so anything that can help to temper this process is a good thing.
As stated above, spirulina and blue spirulina are loaded with phytonutrients that act as antioxidants and are also anti-inflammatory (5, 13, 14, 15, 16, 17). Spirulina effectively lowers the levels of several cytokines, pro-inflammatory proteins that drive the inflammation process started by the immune system, as well as, lowering white blood cell-derived histamine (18, 19, 20).
Strengthens the immune system
The immune system is a complex network involving several cell types, tissues and organ systems (21). Spirulina has phytonutrients and unique sugars, or polysaccharides, that have been shown to stimulate immune function.
Spirulina positively affects immune-related activity in the bone marrow, thymus, and spleen. It may be due to spirulina’s ability to increase the expression of bcl-2, a gene that prevents cells in the bone marrow, spleen and thymus from dying allowing them to meet the challenges place upon them during infections, etc (22, 23).
Spirulina’s potent blue pigment C-phycocyanin and its polysaccharides also increase the production of white blood cells, THE cells of the immune system. Specifically, spirulina can increase the number and activity of macrophages, white blood cells that gobble up pathogens and early cancer cells like Pacman (5, 22, 24, 25).
This awesome blue-green algae increases the activity of natural killer cells as well which attack viruses and tumours. Spirulina appears to protect the various cells of the immune system from damage and toxins, thereby allowing them to do the very disease-fighting job they’re meant to do (5, 22, 24, 25).
Spirulina balances blood lipids
Independent of its ability to lower blood pressure, prevent LDL cholesterol oxidation and reduce inflammation, spirulina and blue spirulina has been shown in several human trials to balance cholesterol and triglyceride levels, a.k.a. “blood lipids” (18, 26). Better ratios of blood lipids is a better predictor of cardiovascular disease than is myopically focusing on LDL cholesterol concentration (27, 28).
Protects your brain and neurons
Spirulina has been shown to protect brain cells from damage, as well as, the mesh of blood vessels that bathe them. By doing so, spirulina has been shown to have neuroprotective effects (5, 29, 30, 31). Neurocognitive disorder, a.k.a. dementia occurs in part to years of oxidative damage.
Spirulina’s antioxidant and anti-inflammatory properties may help to prevent dementia as other phytonutrient and antioxidant-rich plant foods do.
Spirulina may also help to protect microglial cells by reducing inflammation (32, 33). Spirulina may also help maintain brain function and flexibility by supporting pathways that involved BDNF and CREB, both of which support healthy brain function (34, 35).
Reduces risk for cardiovascular disease
Your cell membranes are made up of fatty structures called phospholipids which are susceptible to oxidative damage. This is known as lipid peroxidation and is a driver of many chronic diseases (36, 37). A perfect example of this is the oxidation of “bad” LDL cholesterol which is a pivotal first step in the inflammatory disorder known as atherosclerosis (38).
Reducing LDL damage is an important strategy in reducing the risk of cardiovascular disease. Interestingly, the antioxidants in spirulina are effective at reducing lipid peroxidation in both humans and animals (38, 39).
In a small study of 37 people with Type 2 diabetes, 8 grams (just over 1 Tbsp) of spirulina per day significantly reduced markers of oxidative damage. It also increased levels of antioxidant enzymes in the blood (40).
Maintains a healthy blood pressure
High blood pressure is a well-established risk factor of cardiovascular disease such as stroke, as well as, kidney failure. At 4.5 g (2.5 tsp) per day, spirulina has been shown to reduce blood pressure in those with normal blood pressure, likely by increasing the production of nitric oxide, as a gas that blood vessels produce which causes them to relax and expand (41, 42, 43).
Other clinical studies have demonstrated spirulina’s blood-pressure-lowering effects. In particular, the diastolic blood pressure; the lower of the two numbers which measure the pressure within the blood vessels when the heart is resting between beats. The diastolic reading is considered the more important one when assessing vessel health within the context of high blood pressure. The diastolic pressure significantly decreased in people taking spirulina supplements (44, 45, 46).
As part of a comprehensive lifestyle approach which includes diet and activity/exercise, spirulina and its phytonutrient content, can help to increase your anti-cancer bottom line.
One specific example was a study that showed how 1 g (1/2 tsp) of spirulina, taken for 1 year, helped to resolved oral leukoplakia in 45% of cases in a human trial on 87 tobacco chewers compared to only a 7% resolution in the control group (47).
This is suggestive that it might play a role in reducing the risk of oral cancer as oral leukoplakia (a.k.a. as oral submucous fibrosis or OSMF) is a condition where smokers and tobacco chewers develop a white patch in the lining of their mouths. This tobacco-related patch is associated with an increased risk for oral and throat cancers.
In another study of 40 individuals with OSMF/oral leukoplakia lesions, 1 g (1/2 tsp) of spirulina per day led to greater improvement in OSMF symptoms than the drug Pentoxyfilline (48).
Support liver health
As with many phytonutrients found in various plant foods, spirulina’s phytonutrients may support good liver health by lowering inflammation. The research is limited to mostly rat studies but a human study found that 4.5 g (2 tsp) of spirulina per helped improve symptoms of fatty liver disease (49).
In a diabetic rat model, spirulina protected liver cells against oxidative stress seen with hyperglycemia and hyperinsulinemia and improved markers of liver function (50).
Helps to reduce symptoms of allergic rhinitis
Allergic rhinitis, inflammation in your nasal passageways, is the most common allergic reaction to environmental allergens like pollen, animal hair, or dust. It’s also a major part of asthma. In one clinical study on 127 people, 2 g (1 tsp) of spirulina per day decreased all measured symptoms of allergic rhinitis compared to placebo (51, 52, 53).
Spirulina helps prevent anemia
There are many different forms of anemia including pernicious anemia due to a vitamin B12 deficiency. The most common one is characterized by a reduction in hemoglobin or red blood cells in your blood.
Anemia is more common in older adults than you might think, leading to prolonged feelings of weakness, fatigue and even depression (54). A study of 40 older people with a history of anemia found that spirulina supplements increased the hemoglobin content of red blood cells and improved immune function (55). While not a treatment on its own, spirulina may be an adjunctive strategy.
Improves endurance and strength
Exercise-induced oxidative damage is a major contributor to muscle fatigue. Certain plant foods have phytonutrients that can help to minimize this damage in both athletes and those who are active.
Spirulina appears to improve muscle strength and endurance. It’s been demonstrated to improve exercise energy output and to prevent fatigue (56). Impressively, both short and long-term supplementation with spirulina improved exercise output and delayed fatigue in a small study of 18 adult men.
In two studies, spirulina enhanced endurance and significantly increasing the time it took for people to become fatigued (57, 58). But not all research found this. In a series of 4 trials, spirulina supplementation was unable to improve chronic fatigue (59). More studies are needed but this is interesting nevertheless.
May balance blood sugar
Spirulina has some fascinating research around diabetes management. A meta-analysis of 12 clinical trials found that spirulina was effective at lowering fasting blood sugar and other studies indicate it may improve insulin sensitivity (26, 60).
In some cases, it has outperformed popular diabetes drugs, including Metformin (61, 62, 63). In a two-month study with just 25 people with Type 2 diabetes, 2 grams of spirulina per day led to an impressive reduction in blood sugar levels (64). HbA1c, a marker for long-term blood sugar levels, decreased from 9% to 8%, which is substantial which is considered clinically meaningful.
However, some studies contradict these results. Twelve weeks of spirulina tablets (8 g/day or just over 1 Tbsp) didn’t change blood sugar levels in a group of 37 diabetic Koreans. It’s not clear why, there may be differences in response to spirulina based on different ethnicities and genetics (26, 40).
*As an Amazon Associate, I earn from qualifying purchases. If you’re interested in giving blue spirulina a try, it can be bought here, here, here, here and here.
- 1 Tbsp = 7 g
- 1 tsp = 2.3 g
There isn’t any official dose as spirulina is not approved for therapeutic use by Health Canada nor the FDA.
Both those who use spirulina and supplement manufacturers recommend unofficial dosages based on typical and reasonable amounts. Most recommend and use 1-2 tsp or about 2-4 g per day or per serving.
Where research is concerned, most clinical studies have used a range of dosages when studying spirulina. Most studies that found effects, used doses between 2 g and 10 g or 1 tsp to 1.5 Tbsp per day (5).
Spirulina is by and large very safe. Used in traditional dosages listed above, it shouldn’t be an issue for most people but with a few exceptions (65). Reports, where spirulina was suspected to be a problem, were in those with other comorbidities taking other medications for their management.
Spirulina is contraindicated with those with phenylketonuria or PKU because it contains phenylalanine. As with echinacea and other immune-modulating herbs, spirulina’s immune-boosting effects are likely contraindicated in those with autoimmune diseases and disorders (66).
There’s always a potential for drug interactions when taking herbal products and other plant-based supplements. Spirulina probably should not be combined with immunosuppressive drugs or any medication that is metabolized by CYP450 enzymes.
As stated above, given spirulina’s immune-modulating properties, it’s prudent to avoid taking it if you’re taking an immune-suppressing drug for autoimmune disorders, transplantation management, etc. These include prednisone, cytostatics, cyclosporine, etc.
Spirulina and blue spirulina is a supplement made from drying two species of cyanobacteria, often referred to as blue-green algae.
Blue spirulina is the result of isolating the intense blue-coloured compound phycocyanin from the more intensely green coloured product you’re likely more familiar with. Neither are nutrient-dense but where they shine is in their phytonutrient content. To be clear, spirulina IS NOT a good source of protein when used in typical, and safe, amounts.
Spirulina has been shown to exert many health benefits from lowering blood pressure, improving blood sugar and insulin sensitivity, reducing the risk for some cancers, to improving your blood lipid ratios, supporting brain health and more.
Despite what’s floating around the internet, on social media or being promoted by spirulina manufacturers or some vegan proponents, neither spirulina nor blue spirulina is a source of vitamin B12. Corrinoid, a compound found in spirulina that is structurally similar to B12 HAS NO biological activity and therefore can’t substitute for vitamin B12. Don’t be fooled, know the facts.
While more research is needed before any strong claims can be made, spirulina may a whole food supplement worth adding to your daily regimen but there are some situations where it may interfere with certain medications. Always check with your doctor first.
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Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, and mental health. Follow me on Facebook, Instagram and Twitter.