Harmful effects of chlorella and spirulina | livestrong.com (2023)

Harmful effects of chlorella and spirulina | livestrong.com (1)

Whether spirulina benefits the skin, improves chronic conditions, or otherwise promotes health is up for debate.

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In your search for health-enhancing supplements, you may come across chlorella and spirulina, two types of blue-green algae. You may also come across numerous health claims for these supplements, from spirulina for heavy metal detoxification to chlorella for chronic conditions like hypertension.


Whether spirulina benefits the skin, improves chronic conditions, or otherwise promotes health is up for debate. At best, chlorella and spirulina may provide some health benefits, although these benefits are generally not scientifically proven, according toHarvard Health Publishing.

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In the worst case, there may be adverse effects of taking chlorella and spirulina. Side effects may be more pronounced if these supplements are taken in excessive amounts, according to a February 2017 study.Journal of Applied Physiology. Consult your doctor before adding chlorella and spirulina to your diet to avoid possible adverse effects.


Chlorella, also known as Chlorella vulgaris, is a microalgae that contains proteins, omega-3 polyunsaturated fatty acids, polysaccharides, vitamins and minerals. According to research published inCurrent pharmaceutical designin 2016, number 2.


Spirulina, another microalgae, contains protein, gamma-linolenic acid, linoleic acid, iron, vitamin B12 and other nutrients, he says.University of Rochester Medical Center(URMC). Spirulina and other microalgae can be used as a source of protein and certain vitamins.

However,Winchester Hospitalnotes that spirulina, while nutritious, can be expensive. There are cheaper sources of protein that you can eat, such as legumes, nuts, grains and animal meats. For iron, the options are dark green, plum and meat. You can eat a variety of fruits and vegetables for carotenes and vitamins.


If you decide to supplement with chlorella or spirulina, it's important to get such supplements from a verified source because of the potential for contamination, the URMC says. Spirulina can be contaminated with microbes, radioactive metal ions, and heavy metals, including mercury, cadmium, lead, and arsenic.

Harvard Health Publishing adds that spirulina, like othersdietary supplements, not regulated by the FDA. Therefore, there is no guarantee that any supplement you purchase will be free of contaminants or contain the amount of spirulina listed on the label.



Claims that spirulina can prevent, treat or cure certain conditions, including high cholesterol, hypertension, diabetes, depression, viral hepatitis and malnutrition, are largely unsupported by scientific evidence, adds Harvard Health Publishing. The same applies to claims that spirulina can strengthen the immune system and improve kidney and liver function.

When used in recommended doses, spirulina side effects are rare, according to Harvard Health Publishing. However, spirulina may contain the amino acid phenylalanine and is therefore contraindicated for people with phenylketonuria, a metabolic disorder in which the body cannot metabolize phenylalanine.


Due to the possible side effects of chlorella and spirulina, it is best to consult a doctor or health care professional before taking these supplements, especially if you are taking other medications. The URMC notes that spirulina may affect the effectiveness of blood thinners.

Chlorella and Spirulina side effects

FromJournal of Applied PhysiologyThe study analyzed the use of dietary supplements containing microalgae, including spirulina, chlorella and aphanizomenon. Among the participants was a group of Polish consumers who used microalgae supplements primarily for alleged nutrition, immunity enhancement and detoxification.


According to the survey, consumers mainly used the Internet for information about these dietary supplements and rarely turned to health professionals for advice. In the study, subjects self-reported health benefits such as increased immunity, greater vitality, improved hair and skin quality, and better overall well-being.

Study participants overwhelmingly reported that spirulina had beneficial effects on their skin and that taking chlorella and spirulina improved their hair and scalpskin quality. Although these benefits have not been directly proven, the authors say, the claim is still plausible given the nutritional value of these supplements.



Regarding the side effects of chlorella, aphanizomenon, and spirulina, participants most often complained of diarrhea, nausea, abdominal pain, and rash. Certain pre-existing medical conditions -- namely kidney failure and hypothyroidism, but not Hashimoto's thyroiditis -- reportedly contributed to an increase in side effects.

The side effects of Chlorella and Spirulina can be attributed to their high content of certain compounds, including protein, chlorophyll, phosphorus, iron and manganese.Journal of Applied Physiology. When consumed in excess, these compounds can cause health problems:

  • A high intake of protein, chlorophyll and iron can cause gastrointestinal problems such as diarrhoea, nausea or cramps.
  • Excess phosphorus can have a negative effect on the kidneys.
  • In high concentrations,manganese may contribute to neurotoxicity.

In particular, consumers who consulted experts about the use of microalgae supplements reported significantly less side effects. The study concludes that consumers of microalgae may benefit from consultation with a qualified health professional.

Your doctor or dietitian can advise you on possible side effects and perform the appropriate biochemical tests necessary to determine whether spirulina or chlorella may be beneficial to your health.

Read more:What are the side effects of consuming seaweed?

Don't believe everything you read

It's no surprise that for many consumers, the Internet is the go-to source for health information, say the study's authors. There are many claims on social media, message boards, and diet websites promoting the supposed health benefits of microalgae supplements. For example, these products may be advertised as an adjunctive treatment for people with attention deficit hyperactivity disorder, despite some scientific evidence showing their effectiveness.


Half of the respondents stated that their intention in taking microalgae supplements was to remove body toxins, such as heavy metals. However, claims about the detoxifying effects of chlorella or spirulina are not supported by scientific studies, but are promoted by unreliable internet sources, he says.Journal of Applied Physiology.

In addition, there are no data showing beneficial effects of microalgae supplements on human fertility, the study said. Additionally, there is limited evidence that chlorella can reduce leg swelling during pregnancy. Additional studies are needed to evaluate the safety of microalgae products for pregnant women and their offspring.

Additional security questions

Whether chlorella or spirulina works on the skin, improves chronic conditions, or promotes overall health, it's important to understand the potential risks. Certain forms of blue-green algae can be contaminated with microcystins and anatoxins, which are highly toxic, Winchester Hospital says. Over time and with regular use of blue-green algae supplements, the toxic effects can increase.

Spirulina can also be contaminated with dangerous bacteria if grown using fermented manures from animal waste - or radioactive ions if they are present in the environment.

Side effects of consuming contaminated blue-green algae can include liver damage, abdominal pain, nausea, vomiting, weakness, thirst, rapid heart rate and even death, he says.US National Library of Medicine(NLM). The NLM advises avoiding products that have not been tested for toxins and other contaminants.

However, the NLM indicates that blue-green algae products, when free of contaminants, may be safe for short-term use. Doses of up to 19 grams per day can be used for up to two months, or lower doses of 10 grams per day for up to six months.

If you are considering using spirulina or chlorella, work with your doctor and discuss any concerns you may have. Your doctor can also determine whether these supplements are recommended for short-term or long-term use.

Read more:How much spirulina should I consume?




Harmful effects of chlorella and spirulina | livestrong.com? ›

The most common side effects include diarrhea, nausea, gas, green stools, and stomach cramping. Chlorella can also make the skin extra sensitive to the sun. Wear sunblock outside, especially if you are light-skinned.

What are the side effects of spirulina and chlorella? ›

The most common side effects include diarrhea, nausea, gas, green stools, and stomach cramping. Chlorella can also make the skin extra sensitive to the sun. Wear sunblock outside, especially if you are light-skinned.

Is it safe to take spirulina and chlorella everyday? ›

Yes, it is safe to take spirulina every day. However, 5- 8 grams is considered to be a safe daily dosage. If consumed in high amounts, it may cause some side effects.

Who Cannot take chlorella? ›

Chlorella may make it harder for warfarin and other blood-thinning drugs to work. Some chlorella supplements may contain iodine, so people with an allergy to iodine should avoid them.

What are the hazards of chlorella? ›

Side effects of chlorella include:
  • Allergic reactions, including asthma and other breathing problems.
  • Skin sensitivity to sunlight (photosensitivity)
  • Diarrhea.
  • Nausea.
  • Gas (flatulence)
  • Green discoloration of the stools.
  • Stomach cramping (especially in the first week of use)

Who should not take chlorella and spirulina? ›

Both chlorella and spirulina are popular, nutrient-dense algae supplements that may help lower LDL cholesterol and blood sugar levels. They can be added to your smoothies, salads, and soups. People with autoimmune disorders and on blood thinners should avoid consuming them.

Is chlorella hard on the liver? ›

A recent clinical trial demonstrates chlorella can play an important role in keeping your liver healthy. High levels of certain enzymes can indicate a stressed liver. When people with high levels of these particular liver enzymes took chlorella on a daily basis, their liver enzyme levels dropped.

Who shouldn't take spirulina? ›

People with a metabolic condition called phenylketonuria (PKU) should avoid taking spirulina. People with this rare condition cannot metabolize the amino acid phenylalanine. Spirulina is rich in all amino acids, including phenylalanine.

What happens when you start taking chlorella? ›

Chlorella's fatty acids and minerals like potassium also decrease blood vessel stiffness. This improves the function of blood vessels and lowers blood pressure. Maintaining good cholesterol, blood pressure, and blood vessels reduces your risk of developing heart disease.

Does chlorella detox kidneys? ›

Binds to Heavy Metals, Aiding Detox

In animals, algae, including chlorella, has been found to weaken the heavy metal toxicity of the liver, brain and kidneys (13Trusted Source). Furthermore, chlorella has been shown to help lower the amount of other harmful chemicals that are sometimes found in food.

Can chlorella cause blood clots? ›

Chlorella contains high amounts of vitamin K, which can promote blood clotting and reduce the efficacy of blood thinners like Jantoven (warfarin).

How long does it take chlorella to remove heavy metals? ›

Chlorella with cilantro need to be taken 3 times a day for up to 3 months. According to various studies that heavy metal chelation using cilantro and chlorella can naturally remove an average of 87% of lead, 91% of mercury, and 74% of aluminum from the body within 45 days.

Does chlorella clean the gut? ›

The chlorophyll in chlorella helps keep the bowel clean, while the tough cellulose membrane of chlorella (which is not digested) binds to cadmium, lead and other heavy metals and carries them out of the body. The CGF stimulates repair of tissue damage.

Does chlorella affect thyroid? ›

Chlorella sorokiniana dietary supplementation also affects the thyroid hormone-induced increase in state 3 respiration.

Can chlorella remove heavy metals from the body? ›

Can I use chlorella for heavy metal detox? Yes, chlorella products are ideal for heavy metal removal and detox. The detoxification process is simple: chlorella binds to substances like mercury, cadmium, and other metals and helps your body flush them out.

Does chlorella remove toxins? ›

Chlorella binds with heavy metals and can help flush them out of the body. For this reason, chlorella tablets and powdered chlorella are often used to help people detoxify from these harmful substances. This algae can remove toxin buildup and give your body a fresh start.

What happens when you take chlorella everyday? ›

Chlorella supplements could help promote heart and kidney health, which is essential for normal blood pressure. In one study, people with mildly high blood pressure took four grams of chlorella daily for 12 weeks. By the end, these people had lower blood pressure readings than participants who took the placebo ( 31 ).

Is spirulina hard on the kidneys? ›

These researchers, however, go on to suggest that it is not prudent to eat more than 50 g of spirulina daily. The reason they give is that the plant contains a high concentration of nucleic acids, substances related to DNA. When these are metabolized, they create uric acid, which could cause gout or kidney stones.

Does chlorella block B12 absorption? ›

Absorption and bioavailability are important factors when taking supplements— especially chlorella. The reason why Sun Chlorella is able to raise B12 levels, is likely due to the unique processing method it uses, which allows chlorella's nutrients to become highly digestible and readily absorbed by the body.

Does chlorella affect blood pressure? ›

Reduces high blood pressure

Chlorella promotes heart and kidney function and helps maintain normal blood pressure. Studies suggest that consuming four grams of chlorella daily reduced the incidence of high blood pressure.

What supplements are hardest on liver? ›

How could something natural be bad for your liver? In fact, some common herbs could cause toxic liver disease. Watch out for supplements that contain aloe vera, black cohosh, cascara, chaparral, comfrey, ephedra, or kava.

Does chlorella affect estrogen? ›

GC/MS analysis shows that chlorella can convert E2 to a less active estrogen E1 during biodegradation, and that eventually the levels of both substances decreased. Some data are shown in Fig.

Who should avoid spirulina? ›

People with a metabolic condition called phenylketonuria (PKU) should avoid taking spirulina. People with this rare condition cannot metabolize the amino acid phenylalanine. Spirulina is rich in all amino acids, including phenylalanine.

What are bad side effects of spirulina? ›

Some minor side effects of spirulina may include nausea, insomnia, and headaches. Still, this supplement is widely considered safe, and most people experience no side effects (2). Spirulina may be contaminated with harmful compounds, thin your blood, and worsen autoimmune conditions.

What happens to your body when you take spirulina? ›

Spirulina is rich in a range of vitamins and minerals essential for maintaining a healthy immune system, like vitamins E, C, and B6. Research finds that spirulina also boosts the production of white blood cells and antibodies that fight viruses and bacteria in your body.

Is spirulina hard on the liver? ›

The severity of the liver injury in reports of spirulina hepatotoxicity has varied from mild, asymptomatic elevations in serum enzymes to self-limiting, clinically apparent hepatitis. There have been no reports of acute liver failure, chronic hepatitis or vanishing bile duct syndrome attributed to spirulina.

Why does NASA recommend spirulina? ›

Spirulina or Arthrospira is a blue-green alga that became famous after it was successfully used by NASA as a dietary supplement for astronauts on space missions. It has the ability to modulate immune functions and exhibits anti-inflammatory properties by inhibiting the release of histamine by mast cells.

What toxins does spirulina remove? ›

Spirulina is a very powerful detoxifying agent. It chelates all types of toxins such as mercury, arsenic, radioactive materials, cadmium, pesticides, and environmental carcinogens, eliminating them from the body.

When should you not take spirulina? ›

She also adds that spirulina is high in the amino acid phenylalanine, so it should be avoided by those with phenylketonuria (or PKU), a rare genetic metabolic disorder that makes the body unable to break down the specific amino acid phenylalanine.

What are the cons of spirulina? ›

Because spirulina is harvested in natural waters, failure to adhere to quality control methods allows for contamination with toxins known as microcystins. These substances are toxic to the liver and can cause liver damage.

What organs does spirulina help? ›

It is a source of protein.

It helps your liver to function better by flushing out harmful toxins. Spirulina contains many vitamins, minerals, and antioxidants, which make it a valuable part of any detox diet. It is also very high in protein, making it an essential ingredient for detoxification programs.

Does spirulina burn belly fat? ›

Pooled analysis also showed that Spirulina supplementation led to a significant reduction in body fat percent (with an average reduction of 1.02%) and waist circumference (1.40 reduction), but not in body mass index and waist to hip ratio.

Does spirulina cleanse gut? ›

The Benefits of Spirulina for Cleanses

Not only can spirulina help to support your energy levels with its high protein content, but it also has powerful effects on gut health that can provide the digestive reset you're looking for.

Why not to take chlorella? ›

Chlorella is usually well tolerated, but can cause nausea, diarrhea, abdominal cramping, flatulence, and green stools. Allergic reactions, including asthma and anaphylaxis, have been reported in people taking Chlorella, and in those preparing chlorella tablets.

What does chlorella do to the brain? ›

Chlorella: Rich in Nutrients; and a Known Superfood

The rest of chlorella supplies your brain with B vitamins, vitamins A, C, D, and E and also provides minerals like calcium, iron, phosphorus, magnesium, and zinc. These nutrients are essential in keeping your brain healthy and functioning properly.

Can I take chlorella and spirulina together? ›

It's often recommended to take Spirulina and Chlorella together to get the maximum benefit from these two superfoods. Because of their high levels of chlorophyll and different cell structures, they are amazing for detoxing and flushing out toxins, pesticides, and heavy metals from the body.


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