Spirulina is a type of microalgae that humans have consumed for centuries. Its use dates back to the Aztec civilization of Central America, and it is still commonly eaten in parts of Africa. It is highly nutritious and, in some regions, has served as a primary food source during times of famine.
Spirulina supplements are also becoming increasingly popular, and proponents claim they have numerous health benefits. This article explores the science behind these claims and whether spirulina is worth the hype.
Spirulina is widely considered a superfood. In fact, it is reported to be the most nutritious whole food source found in nature. In 1974, the United Nations named it one of the “best foods of the future.” NASA has also realized its potential, using it as a nutritional source during space travel.
Spirulina contains 60–70% highly digestible protein, consisting of all nine essential and many non-essential amino acids. It is also rich in vitamins, minerals, fatty acids, and antioxidant compounds.
Some of the most notable nutrients in spirulina include:
- Beta-carotene (pro-vitamin A)
- B vitamins
- Vitamin E
- Polyunsaturated fatty acids
However, many of spirulina’s health benefits are attributed to a unique compound called phycocyanin. It is a blue pigment found in certain types of algae with potential antioxidant, immune-enhancing, and antiviral effects.
Unlike many supplements, there is a decent amount of scientific evidence to support spirulina’s effects on human health. Let’s look closer at the current research into its most popular uses.
High in Nutrients
As we have explained, spirulina is packed with protein, vitamins, and minerals. It has even been researched as a treatment for malnutrition, an issue that afflicts many African nations. Malnutrition affects children particularly severely, leading to problems like stunted growth and developmental delays.
A study conducted between June 2012 and February 2013 investigated the impact of spirulina supplementation on malnourished children in Zambia. It involved 60 under-fives who consumed maize porridge with or without spirulina throughout the study.
At the end of the trial, the children in the spirulina group showed significant improvements in height-for-age scores compared to the control group. There were no statistically significant differences in overall body weight or upper arm circumference, although treated subjects displayed slightly larger improvements.
These results are compelling because spirulina is both environmentally-friendly and cost-effective to produce. Therefore, it could provide a feasible solution to the malnutrition and developmental issues that still plague many countries today.
It could also be a valuable nutritional source for vegetarians and vegans as it contains complete protein, which is rare in non-animal products.
Spirulina is widely believed to have antioxidant and anti-inflammatory properties. These effects underly many of its benefits since chronic inflammation and oxidative stress play a role in numerous medical conditions.
Most of the current evidence in this area pertains to experiments on tissue cultures and animals rather than human studies. However, the preliminary findings have been positive overall.
A 2011 review found that spirulina reduced oxidative markers in animal studies. It also suggested that supplementation could inhibit the release of inflammatory compounds like interleukin-6. The benefits of this anti-inflammatory activity could include reducing the impact of exercise-induced muscle damage and conditions like allergic rhinitis.
In a 2020 study, rats underwent a strength training program with or without spirulina for eight weeks. The treated animals received either 50, 150, or 500mg/kg of spirulina daily. The results indicated that the rats in the high-dose spirulina group had reduced levels of C-reactive protein, a marker of inflammation. They also displayed improved antioxidant capacity.
Spirulina appears to improve heart health by reducing harmful cholesterol and triglyceride levels. It may also promote weight loss and reduce blood sugar, all of which play a role in preventing cardiovascular disease. Its anti-inflammatory and antioxidant properties are also relevant since inflammation and oxidative stress contribute to heart disease.
A 2018 review investigated the effects of spirulina supplementation on obesity, inflammation, high cholesterol, and insulin resistance. The included studies indicated that spirulina might benefit heart health by reducing the following:
- Body weight
- Body fat
- Waist circumference
- Body mass index (BMI)
- Total cholesterol
- Low-density lipoprotein (LDL) cholesterol
- Blood pressure
Some studies have also shown that spirulina increases high-density lipoprotein (HDL) cholesterol, which is considered beneficial. However, the evidence in this area is less conclusive.
It seems that many of these effects are due to the presence of the phycocyanin pigment. The review’s authors suggest that this compound inhibits oxidative stress in fat cells, reducing the risk of inflammation and insulin resistance.
May Reduce Blood Pressure
High blood pressure is often a factor in cardiovascular disease and poses a significant health risk in its own right. It seems that spirulina may potentially reduce blood pressure and, therefore, the risk of heart attacks and strokes.
A 2018 meta-analysis included 12 trials on spirulina and blood pressure. It found that the supplement significantly reduced diastolic, but not systolic, blood pressure. “Diastolic” refers to the blood pressure when the heart is resting. Meanwhile, “systolic” refers to the blood pressure when the heart muscle contracts.
The publication also found that spirulina had other beneficial effects, such as reducing cholesterol, triglycerides, and fasting blood glucose. These heart disease risk factors are often elevated in people with high blood pressure.
A more recent meta-analysis from 2021 investigated further. It included five studies on spirulina and blood pressure. Some studies showed decreases in systolic and diastolic blood pressure, while others showed only reductions in one or the other. The paper’s authors suggest that doses of at least 1g daily for at least 12 weeks are necessary to produce significant benefits.
They also proposed that spirulina’s blood pressure-reducing effects may be partially due to its high potassium content. Our complete guide to potassium explains how this essential nutrient affects blood pressure.
Immune System Support
Spirulina also appears to benefit the immune system, influencing the activity of white blood cells and suppressing antigens.
A 2021 study investigated the effect of spirulina supplementation on dogs. The animals were fed a supplemented diet before receiving a rabies vaccine. The treated dogs displayed a faster and stronger reaction to the vaccine than the control animals. This is suggestive of an increased immune response.
The dogs were also put through a demanding exercise challenge. Intensive exercise is known to suppress the immune system and increase the risk of infections. Once again, the treated animals responded positively, showing more stable gut microbiota than the controls. This is relevant because gut health is widely accepted to play a crucial role in immunity.
According to a 2017 review, spirulina may also help to support immunity via its antimicrobial effects. It has shown antibiotic activity against several common bacterial strains, including Escherichia coli and Staphylococcus aureus. It could also promote the growth of beneficial Lactobacillus species, which help support gut health and immunity.
When the immune system becomes hyperactive, it can cause issues like allergies and autoimmune disorders. One common example is allergic rhinitis. In this condition, the immune system overreacts to harmless substances like pollen or dust, causing nasal itching, sneezing, congestion, and a runny nose.
According to a 2020 study, spirulina could help relieve the most common allergic rhinitis symptoms. It tested the algae against cetirizine, a popular antihistamine. After two months, the participants taking spirulina reported more significant improvements in runny nose, congestion, and sense of smell. They also experienced improvements in sleep and daily work and social functions. However, there were no significant inter-group differences in sneezing or nasal itching.
The spirulina group also displayed more significant reductions in inflammatory markers compared to the control group. The study’s authors suggest that reducing inflammation could be the primary way spirulina alleviates allergic rhinitis symptoms.
May Improve Muscle Strength and Endurance
Enhancing exercise performance is another potential spirulina use. Its antioxidant effects may help to counteract muscle damage and fatigue.
A 2022 review found that spirulina increased time to exhaustion in runners and VO2 max in cyclists. VO2 max measures the maximum amount of oxygen the body can use during exercise. Spirulina may also improve recovery heart rate and peak lactate levels in cyclists.
The review’s authors suggest several potential mechanisms behind spirulina’s benefits for athletes, including:
- Antioxidant effects
- High protein content
- Relaxing the arteries to promote circulation
- High iron content (iron is necessary for oxygen transportation)
However, the current evidence is sparse, and further research is warranted.
Humans have consumed spirulina for centuries with few reports of adverse effects. The FDA has designated the supplement Generally Recognized as Safe (GRAS).
However, there are several potential health risks associated with spirulina use. Many of these relate to contaminated products. While carefully cultivated spirulina should be safe, algae grown in open water may contain heavy metals and liver toxins known as microcystins.
Consuming contaminated products could result in liver damage and various side effects, including:
- Increased heart rate
Therefore, it is essential to only purchase spirulina from brands that provide detailed lab reports for all their products. These documents are the best way to ensure that a supplement is safe and contaminant-free.
However, even high-quality spirulina can cause issues in some individuals. For example, some people are allergic to spirulina, and reactions can be severe. Spirulina allergies may cause:
- Burning sensations on the soles of the feet
- Breathing difficulties
- Anaphylactic shock
The supplement can also interact with numerous medicines, including antidiabetic drugs, anticoagulants, and antiplatelet drugs. It should not be taken alongside these medications or herbs or supplements that affect blood sugar or clotting.
Furthermore, spirulina can affect iron absorption and may be unsuitable for people with anemia. Individuals with autoimmune conditions should also exercise caution due to its immune-enhancing effects.
Even healthy individuals may experience spirulina side effects, including:
Spirulina is considered possibly unsafe for children due to their increased sensitivity to toxins. Its safety in pregnancy and breastfeeding has not been determined.
Finally, it is recommended to stop taking spirulina at least two weeks before scheduled surgery due to its effects on blood glucose and clotting.
How to Use Spirulina
Many spirulina supplements are available, including spirulina powder, capsules, and tablets. The powder can be added to food and drinks and often provides the best value for money. However, many people do not enjoy the algae’s natural flavor and prefer to take spirulina capsules or tablets instead.
As we mentioned earlier, spirulina products are prone to contamination, posing significant health risks. Therefore, it is paramount to only purchase from brands that provide up-to-date lab reports.
There is no standard spirulina dosage, and research studies have used daily doses of 1–19g for anywhere between 2–48 weeks. Many studies have involved doses of 2–4g daily, so this might be a good starting point for most people.
Doses up to 19g are considered safe for periods of up to two months, while doses up to 10g are considered safe for up to six months. We advise individuals to consult a healthcare provider to determine the safest and most effective dose for them.
Final Thoughts on Spirulina
Spirulina has some impressive benefits, and there is a relatively large body of evidence to support many of them. Some common reasons people use spirulina include supporting heart health and immunity and boosting overall nutrition.
Although spirulina is generally considered safe, poorly manufactured products may be dangerous due to the risk of contamination. Moreover, supplements are not appropriate for people with specific conditions or those taking certain medications.
We recommend consulting a professional before beginning any new supplement regime and starting with a low dose to gauge its effects.
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