Spirulina is classified into the class of cyanobacteria (meaning, it is bluish-green in color). It is a simple form of algae with very high nutrient value.
It is a very rich source of proteins and has no cholesterol.
It also consists of vitamins B12 and B-6, vitamin A, vitamin C vitamin D, magnesium, calcium, and iron. 
It is commercially available in the form of tablets, powder, and capsules and is consumed by many people for the tremendous benefits that it has for the body.
Capable of growing in salty as well as fresh water, this organism contains many amino acids and is also a complete protein. 
Its benefits were known even in the ancient times when it was consumed by the Aztecs ( Pre-Columbian Mesoamerican people belonging to Mexico).
Later, it was proposed by NASA that it could be grown in space as well and used by astronauts. 
The most astonishing and beneficial effect that it has is on the brain. Studies and investigations were also carried out to confirm it.
The world is becoming a competitive space with difficulty that elevates every day. It is more like a rat race.
One needs to be very sharp, vigilant and focused to succeed. It is at this point of time that the brain needs nourishment to work at its best. Spirulina is very helpful in such cases.
4 Surprising Benefits of Spirulina For Brain Health
A study was published in “Santepublique” in 2009 which reported that school children (seven years of age) consumed 2 grams of spirulina along with 10g of honey over a period of 60 days.
Their grades were calculated and compared to those which were obtained before the supplementation.
It was observed that their academic performance had enhanced. This proved that Spirulina could sharpen the brain.
Similarly, it protects the brain in many ways. To know more, read ahead.
1. Spirulina has Antioxidant Property
Oxidative stress can cause tremendous damage to the cells of the body, the DNA, cause cancer as well as chronic inflammation. 
Free radicals can potentially damage cells and need electrons to balance themselves. They can also cause brain injury. 
The difficult and tiring lifestyles, exhausting schedules and severe life stress can also result in oxidative stress.
Spirulina helps in avoiding oxidative stress as well as protects the brain against the damage that it may cause.
A study was published in “The Journal of Nutritional Science and Vitaminology” in 2011 which reported that spirulina reduced the deposition of the protein “amyloid β.” 
This protein is found in the form of “amyloid plaque” in the patients suffering from Alzheimer's disease and is toxic to the neurons.
This prevents memory loss and also protects the brain against oxidative stress by enhancing the activity of the enzyme “Glutathione peroxidase” which is an antioxidant enzyme.
Spirulina also consists of an active ingredient, known as “phycocyanin” (which is a pigment).
It imparts the characteristic blue-green color to the algae.
This prevents the expression of an enzyme (inducible nitric oxide synthase) which may elevate oxidative stress through the production of nitric oxide. 
It was also observed that it had neuroprotective effects on animal brains.
What does this Mean? Spirulina protects the brain against oxidative stress which might result in brain injury or memory loss.
2. Spirulina has a Protective Effect on the Brain
Spirulina can protect the brain against a number of diseases and risk factors.
Since it enhances antioxidant activity and prevents radical-mediated cell death, it can be useful in the treatments for neurodegenerative disorders.
The oxidative stress caused due to the presence of iron can be prevented, thereby inhibiting the development of diseases such as Parkinson’s and Alzheimer's diseases. 
Apart from that, ischemia may occur as a result of oxidative stress, where the blood supply gets inadequate for the muscles of the heart and the brain.
Focal brain ischemia or brain ischemia may occur if there is a blood clot in the cerebral region of the brain.
In such cases, free radicals and aging are involved and cause neurodegeneration.
When animals were fed a diet consisting of spirulina, spinach, and blueberry, for 4 weeks, it was observed that the infarction (lack of blood supply) to the brain had reduced.
The locomotor activity (movement for physiological or behavioral functions) had enhanced.
The activity of a protein, known as caspase-3 was also lowered, which takes part in apoptosis (programmed cell death) in the brain. 
ADHD (Attention deficit hyperactivity disorder) may affect children and teenagers and persist into adulthood.
According to a study published in “The Journal of Attention Disorders”,in the year 2010, it was observed that a compound herbal preparation consisting of spirulina, when given to children diagnosed with ADHD for a period of 4 months, there were significant changes.
The children had an improved impulse control, attention as well as cognition. 
What does this Mean? Spirulina protects the brain against ischemia and infarction. It also protects the brain from the risk factors associated with Parkinson’s and Alzheimer’s diseases.It can also benefit those suffering from ADHD.
3. Spirulina Prevents High Blood Pressure and Blood Sugar Levels
Due to high blood sugar levels, or, in the case of diabetes, the renal function can get disturbed, which in turn has a bad effect on the regulation of blood fats.
This results in abnormal cholesterol levels.
It can also lead to atherosclerosis, where plaque begins to form in the arteries, increases the blood pressure and may lead to myocardial infarction and stroke.
In such cases, it is the atherosclerosis of the carotid arteries (which are two in number and carry oxygenated blood from the heart to the brain) which can lead to an ischemic stroke.
Spirulina helps in the reduction of blood glucose as well as glycosylated serum protein. 
It can help to combat type-2 diabetes too, as it can enhance insulin sensitivity, thereby eliminating insulin resistance and the reduction of random blood glucose levels. 
It also showed hepatoprotective and anti-hyperglycaemic effects in an animal study. 
The blood pressure can be reduced because of an increase in the secretion as well as the synthesis of nitric oxide, which causes the blood vessels to dilate, making the blood flow easier. 
What does this Mean? Spirulina keeps the blood pressure, diabetesand blood sugar levels in control in order to avoid cardiovascular diseases which may lead to stroke and injure the brain.
4. Spirulina improves Metabolic Health and Lowers Bad Cholesterol
Lipid peroxidation can also lead to heart diseases which are a risk factor for stroke. 
Non-alcoholic fatty liver disease (NAFLD), which occurs due to abnormal lipid levels and can cause cardiovascular diseases is associated with ischemic stroke. 
Spirulina or blue-green algae was found to reduce the hepatic lipid levels. 
According to a study published in “Lipids in Health and Disease” in the year 2007, Spirulina was found to have an antihypertensive and antihyperlipidemic effect.
When individuals consumed 4.5g of Spirulina for a period of 6 weeks, the triglyceride and LDL levels reduced. The systolic and diastolic blood pressure also reduced. 
The cholesterol-lowering effect of spirulina was also observed when subjects consumed 8g of spirulina for 16 consecutive weeks.
It decreased the secretion of a protein known as interleukin-6, which leads to inflammation. It hence had an anti-inflammatory effect.
It increased the activity of an antioxidant enzyme known as superoxide dismutase to inhibit the development of oxidative stress.
It also resulted in a drop in the total cholesterol level.  Spirulina, as little as 1 g can also have a great impact on the cholesterol levels.
A study published in “Journal of The Science of Food and Agriculture” in 2014, it was reported that the consumption of 1 g of spirulina for 12 weeks lowered LDL by 10.1% and triglycerides by 16.3%.
What does this Mean? Spirulina can lower the total cholesterol, triglycerides and LDL levels. By reduction of all these, it prevents atherosclerosis which can result in ischemic stroke, if occurred in the carotid arteries. It also controls non-alcoholic fatty liver disease which is associated with ischemic stroke.
Dosage of Spirulina For Brain Health
Spirulina can be consumed in the form of powders, capsules and tablets commercially available.
According to studies, doses as less as 1g per day have been found to be effective. However, one can go up to 8 grams of spirulina per day.
Though Spirulina has been found to reduce heavy metal toxicity (caused due to arsenic) and it also works to get rid of the symptoms associated with allergic rhinitis , one may still be allergic to it and reactions such as vomiting, stomach pain, and headache may result.
Care must be taken before incorporating it into the diet for improved performance and memory. A doctor must be consulted.
Spirulina can be taken by children, teenagers, and adults as well, to protect the brain from any risk factors such as blood pressure, diabetes, abnormal cholesterol levels, and ischemic stroke.
It helps in the improvement of memory, focus, protects the brain against neurodegenerative diseases and sharpens it.
However, care must be taken before fully committing to the consumption of this supplement on an everyday basis.