Evidence: Very High Possible Benefits: Very High Safety: Very High
TABLE OF CONTENTS
What is Spirulina?
Spirulina is a type of algae commonly used as a dietary supplement for its wide variety of benefits. This article is about the main benefits of spirulina, its potential side effects, the best time to take it, and more.
Possible benefits
All of the potential benefits mentioned below are dose-dependent. As with most other supplements, there is a sweet-spot dose that allows you to get most of the benefits without causing meaningful side effects or tolerance buildup in the body. We will discuss the best dosing protocol later in this article.
Major benefits
Improved liver health – Spirulina is incredibly effective at reducing liver enzymes and even more effective at reducing liver fat.
Reduced blood pressure – Supplementation with regular doses for 6 weeks can reduce both systolic and diastolic blood pressure in hypertensive and nonhypertensive people by about 11/6 points.
Reduced triglycerides – Spirulina can greatly reduce triglyceride levels in people with metabolic syndrome, diabetes, hyperlipidemia, hypertension, and those with high triglyceride levels caused by other reasons. The reductions are typically in the range of 10-15%.
Improved immune health – Secondary to the other benefits, spirulina can greatly strengthen immune system health and function. For example, it was shown in human studies to increase natural killer cell count and activity by 40-55%. This supplement can also reduce the symptoms of various autoimmune conditions.
Improved allergies – Spirulina is extremely effective at reducing the intensity of allergies. It can diminish symptoms like nasal congestion, nasal discharge, sneezing, and itching.
Increased power output – One study found that supplementation for 8 weeks increased power output by 20-30%. The supplement seems more helpful in this regard for untrained people but can improve power output in trained individuals as well.
Minor benefits
Heavy metal detoxification – Spirulina can help detoxify the body from arsenic and other heavy metals.
Reduced symptoms of oral cancer – In one human study, one gram of spirulina daily fully healed lesions caused by oral cancer in 44% of participants while the placebo only healed the lesions in 7% of people.
Improved cholesterol levels – Spirulina can increase HDL and reduce LDL cholesterol levels. This benefit is of a small magnitude but highly reliable. In people with fatty liver disease, the reductions in LDL can be significantly higher.
Reduced inflammation – Spirulina is anti-inflammatory and can improve various markers of inflammation in the body.
Antioxidant properties – The supplement has strong antioxidant properties and can reduce damage caused by free radicals and oxidative stress.
Reduced HbA1c – One human study found a decrease from 9% to 8% with 2 grams of spirulina.
Improved insulin sensitivity – This benefit appears small and more studies are needed to confirm it.
Improved muscular endurance – Spirulina can slightly increase muscular endurance.
Fixing nutrient deficiencies – Spirulina contains relatively high amounts of B vitamins, zinc, iron, copper, vitamin K1, and a few more nutrients. Because of these vitamins and minerals, spirulina can have various other benefits unmentioned in this article, especially if you are deficient in them.
Possible side effects
The side effects below are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.
Allergic reaction – An allergy to this supplement is rare but possible.
Nausea – This side effect is most common when people take the supplement on an empty stomach.
Diarrhea – You can usually prevent diarrhea or stomach discomfort by taking this supplement with a meal.
Toxicity – While acute toxicity is extremely rare, taking high amounts of this supplement could lead to chronic toxicity and cause health problems over time. Regularly taking high doses can also cause the body to develop a tolerance to the supplement. To prevent chronic toxicity or the buildup of tolerance, staying below 8 grams in a day is best unless you have a great reason to take more.
Contamination – Contaminated supplements are uncommon in the USA and other well-regulated countries. However, if you wish to buy products from China, India, or other countries without strict regulations, beware that the supplements may be contaminated. Either way, you need to choose the brand you order from wisely. Always read through some reviews for the specific product before you buy it. The FDA (Food and Drug Administration) has the power to regulate dietary supplements but can only do so after they have been on the market for a while. That’s because supplement companies are not obligated to announce to the FDA when releasing a new product. The FDA has to discover the product and test it for potential impurities, which can take a lot of time. During that time, the supplement can be sold on the market even if it’s impure. Also, supplement companies can change their manufacturers without announcing it to the FDA.
Who should not take spirulina?
You should probably avoid taking spirulina if you:
are allergic to this supplement
experience a severe adverse reaction after taking the supplement
are pregnant or breastfeeding (while it can be safe to take this supplement during pregnancy or breastfeeding, it can put some unnecessary risk to the child)
Who will benefit the most?
You should consider taking the supplement if you:
often experience allergies
have an unhealthy liver
do lots of resistance training and wish to maximize exercise performance and power output
suffer from heavy metal poisoning or have high levels of heavy metals in the body
have unhealthy cholesterol or triglyceride levels
are diagnosed with NAFLD or other metabolic diseases
have a high budget for supplements and are willing to experiment with a variety of them (assuming you don’t fall into any of the categories that should avoid this supplement, spirulina appears relatively safe and is unlikely to do more harm than good for most people)
How much spirulina should you take?
The sweet spot dose typically ranges between 2-6 grams daily for most people. This amount should provide most of the benefits without meaningful side effects.
The higher end of this range usually provides slightly more benefits in the short term. If you plan to take this supplement for a longer time (multiple months or years), the lower end is probably a better way to go since it is safer, and you would develop tolerance faster if you were to take higher doses.
The upper safety limit for this supplement is not well-established. To stay on the safe side, don’t take more than the recommended dose unless you have a great reason to do so. Higher amounts may cause problems if you take the supplement for a prolonged period.
Like most other supplements, it is best to cycle spirulina and take about two days off weekly to reset your tolerance. That will allow you to keep getting the benefits in the long term.
Best time to take spirulina
The main bioactive compounds in spirulina are water-soluble, so you don’t have to take spirulina with food to absorb it well.
Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
Where to buy spirulina?
In most countries, Amazon is the best option for ordering spirulina supplements. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the Internet.
Some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.
Spirulina vs. chlorella
While these two types of algae have a similar chemical composition, there are a few key differences between them.
Chlorella is generally richer in micronutrients per gram. It is also one of the very few vegan sources of vitamin B12, which spirulina lacks.
Spirulina, on the other hand, is generally much richer in phytonutrients, such as phycocyanobilin. It is also more studied than chlorella and the studies generally show more promising results.
While both types of algae can be beneficial, spirulina is generally a much better choice with greater benefits.
FAQ
Like most other supplements, it is best to cycle spirulina and take a break from it for about two days per week to reset your tolerance back to baseline. That will keep your body sensitive to the supplement and allow you to keep getting the benefits in the long term.
All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes time which can add up over months or years. The disadvantage of capsules is that they are often made of bovine gelatine, which rarely comes from ethical sources.
Yes. Whether you take the supplement in the morning or the evening does not make much difference. Both options are fine so feel free to experiment.
This supplement should not become harmful once it exceeds the expiration date. However, it can lose potency over time. Keep this supplement in a cold, dark, and dry place so it remains as potent for many months or even years.
While acute toxicity is rare, taking very high amounts of this supplement could lead to various problems over time. High doses can also make you develop tolerance much faster than lower doses.
While you could safely take higher doses, there is usually no point in taking more than 6 grams daily. This amount should give you most of the benefits without meaningful side effects.
Unfortunately, not much is known about the half-life of spirulina in the body. However, most of the effects of this supplement are cumulative, so they mainly happen in the long term rather than acutely. Therefore, the half-life of this supplement isn’t very relevant in practice.
In the long term, you must take the supplement for about 2-4 weeks to begin noticing most of the benefits.
Yes, spirulina is vegan-friendly. If you buy the supplement in a capsulated form, beware that the capsules often contain animal-based gelatin. Instead, find a brand that puts its products into cellulose capsules.
No, it does not. The supplement should not interfere with fasting in any significant way. However, you still want to take the supplement with food as it will absorb better.
References
Most of the information in this guide is based on scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything you read in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.
