The Harmful Effects of Chlorella and Spirulina

In the quest for supplements to boost your health, you may encounter chlorella and spirulina, two types of blue-green algae. You may also encounter a number of claims about these supplements’ health benefits, from spirulina for heavy metal detox to chlorella for chronic conditions like hypertension.

About Chlorella and Spirulina

What to Know If You Plan to Take One

Spirulina, while nutritious, can be expensive. There are more inexpensive sources of protein you can eat, such as legumes, nuts, grains, and animal meat. For iron, options include dark greens, prunes, and meat. For carotenes and vitamins, you can eat a variety of fruits and vegetables.

Claims that spirulina can prevent, treat, or cure certain conditions, including high cholesterol, hypertension, diabetes, depression, viral hepatitis, and malnutrition, are largely unsubstantiated by scientific evidence. The same is true of claims that spirulina can boost the immune system and improve kidney and liver function.

Chlorella and Spirulina Side Effects

A Journal of Applied Phycology study analyzed the use of microalgal food supplements, including spirulina, chlorella, and Aphanizomenon. The participants included a group of Polish consumers who used microalgal supplements mainly for their purported nutritional, immune-boosting, and detoxifying purposes.

According to the study, the consumers primarily used the internet for information on these supplements, rarely turning to health specialists for guidance. In the study, respondents self-reported health benefits such as increased immunity, higher vitality, improved hair and skin quality, and greater overall well-being.

Study participants largely reported that spirulina benefits skin and that chlorella and spirulina intake had improved their hair and skin quality. Although these benefits are not directly evidenced, say the authors, the claim is nonetheless plausible, given the nutritional content of these supplements.

As for chlorella, Aphanizomenon, and spirulina side effects, the most common complaints among participants were diarrhea, nausea, abdominal pain, and skin rash. Certain preexisting medical conditions — namely, renal failure and hypothyroidism, but not Hashimoto’s thyroiditis — reportedly contributed to an increase in side effects.

Chlorella and spirulina side effects may be attributable to their high content of certain compounds, including protein, chlorophyll, phosphorous, iron, and manganese, says the Journal of Applied Phycology. When consumed in excess, these compounds can present health concerns:

• High intake of protein, chlorophyll, and iron may cause gastrointestinal issues, such as diarrhea, nausea, or cramps.
• Excess phosphorus can adversely affect the kidneys.
• In high concentrations, manganese may contribute to neurotoxicity.

Notably, those consumers who consulted with specialists on the use of microalgal supplements reported adverse side effects significantly less often. The study concludes that microalgal consumers may benefit from consulting with a qualified health professional.

Your doctor or dietitian can advise on potential side effects and conduct the proper biochemical testing needed to determine whether spirulina or chlorella may be beneficial for your health.

Don’t Trust Everything You Read

It’s no surprise that the internet serves as a resource for many consumers in search of health information, say the study authors. Claims abound on social media, message boards, and diet websites promoting the alleged health benefits of microalgal supplements. For example, these products may be marketed as a supportive treatment for people with attention deficit hyperactivity disorder, despite any scientific evidence proving their effectiveness.

Half of the study respondents stated that their intention in using microalgal supplements was to eliminate bodily toxins, such as heavy metals. However, claims about chlorella or spirulina heavy metal detox effects are not supported by scientific studies but rather promoted by unreliable internet sources.

In addition, there is no data demonstrating the beneficial effects of microalgal supplements on human fertility, says the study. Furthermore, there is limited evidence that chlorella may reduce leg swelling during pregnancy. Additional studies are needed to assess the safety of microalgal products for pregnant people and their offspring. Always consult your primary care physician before taking any medication or supplement during pregnancy.

Additional Safety Concerns

Regardless of whether chlorella or spirulina benefits skin, improves chronic conditions, or aids overall health, it’s important to understand the possible risks. Certain forms of blue-green algae may be contaminated with microcystins and anatoxins, both highly toxic substances. Over time and with regular use of blue-green algae supplements, the toxic effects may multiply.

Spirulina may also be contaminated by dangerous bacteria if grown with the use of fermented animal waste fertilizers — or by radioactive ions if they’re present in the environment.

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

If you’re considering using spirulina or chlorella, work with your healthcare provider and discuss any concerns. Your doctor can also determine whether these supplements are advisable for short-term or long-term use.

The Takeaway

• While there exists much discussion regarding the potential health benefits of blue-green algae like spirulina and chlorella, these benefits have generally not yet been verified scientifically.
• It’s best to consult with your doctor before beginning use of chlorella and spirulina.
• Be sure not to consume the supplement in excess in order to prevent the likelihood of negative side effects.