Chlorella vs. Spirulina: What's the Difference Between These Microalgaes?

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Medically reviewed by Simone Harounian, MS

Spirulina and chlorella are types of microalgae, which are a large group of mostly aquatic microorganisms.

Both of these microalgae are rich in nutrients such as protein, vitamins, minerals, fatty acids, and a variety of antioxidant and anti-inflammatory plant compounds. Spirulina and chlorella are commonly taken in supplement form and are added to juices, smoothies, and other health food products to boost their nutritional value.

They both have impressive nutritional profiles and have been shown to benefit health in several ways, from reducing heart disease risk factors to boosting exercise performance. However, there are some important differences between the two.

Here’s everything you need to know about chlorella and spirulina, including their nutrition, health benefits, similarities, and differences.

Benefits of Chlorella

Chlorella is a green algae that grows in freshwater environments. It’s mass-produced for use in dietary supplements and health food products like greens powders.

When taken as a supplement, chlorella may benefit health in several ways. For example, chlorella might help reduce heart disease risk factors such as high LDL cholesterol, high blood pressure, and elevated blood sugar levels.

A 2018 review of 19 studies found that, when taken in doses higher than 4 grams per day for eight weeks or longer, chlorella supplements significantly decreased total cholesterol, LDL cholesterol, systolic and diastolic blood pressure, and fasting blood sugar levels in healthy people and in those with elevated cholesterol and blood pressure levels.

Chlorella is also packed with antioxidant compounds, such as the carotenoids lutein and zeaxanthin, and may boost the body’s antioxidant levels. For example, a 2021 study found that a single 6-gram dose of chlorella significantly increased blood levels of the carotenoids lutein, beta-carotene, and zeaxanthin in healthy men.

Higher blood levels of carotenoids could benefit overall health and protect against conditions like certain cancers and age-related macular degeneration (ARMD).

Chlorella may also be effective for enhancing exercise performance, improving immune function, and supporting healthy body composition, though more research is needed.

Benefits of Spirulina

Spirulina is a blue-green algae that grows in both fresh and salt water. It’s nutrient-dense and, like chlorella, may benefit cardiovascular health when taken as a supplement.

A 2023 review of 20 studies found that spirulina treatments significantly reduced LDL cholesterol, total cholesterol, and triglyceride levels while significantly increasing heart-protective HDL cholesterol. The researchers noted that spirulina was most effective for reducing total cholesterol and triglycerides when taken in doses of 9 grams and 6 grams per day, respectively.

Study findings also suggest that spirulina supplements may support body weight management, reduce blood pressure levels, and promote blood sugar control.

Spirulina seems to be effective in reducing markers of inflammation and boosting the body’s antioxidant capacity. A 2021 review of nine studies found that spirulina supplements increased the total antioxidant capacity of the blood and increased the activity of the antioxidant enzyme superoxide dismutase (SOD), which scavenges free radicals and helps protect against cellular damage.

Additionally, spirulina may have beneficial effects on exercise performance by improving exercise tolerance and increasing oxygen uptake, but research findings are mixed.

Nutritional Facts of of Chlorella and Spirulina

Though the nutritional content of chlorella and spirulina products vary based on sourcing and production methods, they’re both nutritious, providing vitamins, minerals, and protein.

Here’s the nutrition breakdown for a 2-teaspoon serving of chlorella and spirulina powder.

Spirulina and chlorella are low in calories but provide a decent amount of protein. These powders are low in carbs and suitable for those following very low-carb diets, like the ketogenic diet.

Both are good sources of vitamin A, which is needed for immune function, growth and development, cellular communication, and reproduction.

Spirulina and chlorella also provide plant-based iron, which is required for the production of hemoglobin, a protein that carries oxygen throughout the body. It’s also needed for cellular function, growth and development, and the production of certain hormones.

Spirulina is a good source of iron, folate, vitamin K, vitamin E, and thiamin, while chlorella is higher in folate, vitamin A, niacin, and vitamin C.

However, keep in mind that while these algae are rich in certain nutrients, some of these vitamins and minerals are found in forms that are less bioavailable to the human body. For example, the B12 and iron in spirulina supplements are often found in biologically inactive forms that aren’t effective in boosting levels of these important nutrients.

Chlorella is also a good source of omega-3 fats and is higher in these protective compounds than spirulina.

Similarities of Chlorella and Spirulina

Chlorella and spirulina have many similarities. They’re both nutritious and contain a similar amount of protein and calories.

Both provide vitamin A, potassium, and iron, all essential for overall health. These microalgae are also packed with phytochemicals such as the carotenoids beta-carotene, lutein, and zeaxanthin, and phenolic compounds like p-Coumaric acid and ferulic acid.

They’ve both been shown to benefit health in similar ways. For example, supplementation with chlorella and spirulina may help reduce heart disease risk factors such as high LDL cholesterol and hypertension (high blood pressure). Both may also support a healthy body weight and might boost exercise performance.

Overall, these algae share plenty of similarities, but they have some key differences, too.

Differences of Chlorella and Spirulina

There are some differences between chlorella and spirulina, including their composition and nutritional value.

Chlorella is considered unicellular, meaning it consists of a single cell. Spirulina is made up of multiple cells and is categorized as multicellular.

Though both are nutritious, they provide different amounts of certain nutrients. Spirulina is higher in protein than chlorella, containing up to 70% protein by weight while chlorella contains approximately 59% protein.

Additionally, chlorella is higher in vitamin A, niacin, riboflavin, and B6, while spirulina is a better source of vitamin E, thiamin, and vitamin K.

Chlorella also contains more omega-3 fats, while spirulina contains more omega-6 fats in the form of γ-linolenic acid (GLA), both of which have anti-inflammatory properties.

Which Is Better for Health?

Though there are some slight nutritional differences between the two, chlorella and spirulina are both beneficial for health.

Supplementing with either of these algae may reduce heart disease risk factors, improve body composition, boost exercise performance, and help you meet your daily nutrition needs.

While they have different nutritional makeups, both provide a good source of vitamins and minerals and are rich in health-promoting compounds, such as carotenoid antioxidants and fatty acids.

You can purchase spirulina and chlorella in multiple forms, such as powders, capsules, and tablets, making them a convenient choice for improving your diet quality. For example, powered spirulina and chlorella can be added to smoothies, oatmeal, and energy bites for a quick boost of nutrients.

However, like most supplements, you should check with your healthcare provider before adding chlorella or spirulina to your diet. Both may cause side effects like diarrhea, upset stomach, and gas and may not be the best choice for people with certain health conditions or those taking certain medications.

A Quick Review

Spirulina and chlorella are types of types of microalgae that are commonly taken in supplement form.

Though there are some small differences between the two, both are nutritionally similar and may improve heart health, support weight loss, improve exercise performance, and boost dietary quality when consumed regularly.

Read the original article on Health.com.