Chlorella and spirulina are forms of algae that have been gaining popularity in the supplement world.

Both have impressive nutrient profiles and potential health benefits, such as lowering risk factors for heart disease and improving blood sugar control (1).

This article reviews the differences between chlorella and spirulina and assesses whether one is healthier.

Chlorella and spirulina are the most popular algae supplements on the market.

While both boast an impressive nutritional profile and similar health benefits, they have several differences.

Chlorella is higher in fat and calories

Chlorella and spirulina deliver a number of nutrients.

A 1-ounce (28-gram) serving of these algae contains the following (2, 3):

Calories115 calories81 calories
Protein16 grams16 grams
Carbs7 grams7 grams
Fat3 grams2 grams
Vitamin A287% of the Daily Value (DV)3% of the DV
Riboflavin (B2)71% of the DV60% of the DV
Thiamine (B1)32% of the DV44% of the DV
Folate7% of the DV7% of the DV
Magnesium22% of the DV14% of the DV
Iron202% of the DV44% of the DV
Phosphorus25% of the DV3% of the DV
Zinc133% of the DV4% of the DV
Copper0% of the DV85% of the DV

While their protein, carbohydrate, and fat compositions are very similar, their most notable nutritional differences lie in their calorie, vitamin, and mineral contents.

Chlorella is higher in calories, as well as omega-3 fatty acids, provitamin A, riboflavin, magnesium, iron, and zinc.

Spirulina is lower in calories but still contains a high amount of riboflavin, thiamine, iron, and copper.

Chlorella contains higher levels of omega-3 fatty acids

Chlorella and spirulina contain similar amounts of fat, but the type of fat differs greatly.

Both algae are particularly rich in polyunsaturated fats, especially omega-3 fatty acids (4, 5, 6, 7).

Omega-3 and omega-6 fatty acids are essential polyunsaturated fats that are important for proper cell growth and brain function (8).

They are considered essential because your body is unable to produce them. Therefore, you must obtain them from your diet (8).

Intake of polyunsaturated fats has been associated with a lower risk of heart disease, particularly when substituted for saturated fats (9, 10, 11, 12).

Omega-3 fatty acids, in particular, are associated with numerous health benefits, including reduced inflammation, improved bone health, and a lower risk of heart disease and certain cancers (13, 14, 15).

However, you would need to consume very large amounts of these algae to meet your daily omega-3 needs. People typically only consume small portions of them (16).

While both forms of algae contain various types of polyunsaturated fats, a study that analyzed the fatty acid contents of these algae found that chlorella contains more omega-3 fatty acids, while spirulina is higher in omega-6 fatty acids (5, 17).

Though chlorella offers some omega-3 fats, concentrated algal oil supplements are a better option for those seeking alternatives to animal-based omega-3 supplements.

Chlorella is high in antioxidants

In addition to its high levels of polyunsaturated fat, chlorella is very high in antioxidants. These are compounds that bind with free radicals in your body to prevent damage to cells and tissues (18).

One 6-week study gave a chlorella supplement to people who smoked cigarettes.

Participants who received the supplement experienced a 44% increase in blood levels of vitamin C and a 16% increase in levels of vitamin E. Both of these vitamins have antioxidant properties (19).

Furthermore, those who received a chlorella supplement also showed a significant decrease in DNA damage (19).

Spirulina may be higher in protein

Civilizations as far back as the Aztecs have used spirulina as food (20).

Due to its high protein content, NASA has used spirulina as a dietary supplement for their astronauts during space missions. It’s also a rich source of iron, folate, and beta carotene (20).

While chlorella and spirulina both contain high amounts of protein, studies have indicated that some strains of spirulina can contain up to 10% more protein than chlorella (21, 22, 23, 24).

The protein found in spirulina is also very well absorbed by your body (21).

Summary Chlorella is rich in omega-3 fatty acids, vitamin A, riboflavin, iron, and zinc. Spirulina contains more thiamine, copper, and possibly more protein.

Numerous studies have shown that both chlorella and spirulina may benefit blood sugar control.

Exactly how this works is unknown, but a few animal studies have indicated that spirulina may help increase insulin sensitivity (25, 26).

Insulin sensitivity is a measure of how well your body uses your blood sugar for energy.

Furthermore, several human studies have found that taking chlorella supplements may increase blood sugar control and insulin sensitivity. These effects may be particularly beneficial for those with diabetes or insulin resistance (27, 28, 29, 30).

Summary Some research shows that spirulina and chlorella may help lower blood sugar levels. However, research on spirulina has been limited to animal studies.

Studies have shown that chlorella and spirulina have the potential to improve heart health by affecting your blood fat composition, blood pressure, and cholesterol profile.

In one controlled 4-week study, 63 participants who were given 5 grams of chlorella daily showed a 10% reduction in total triglycerides, compared with a placebo group (30).

Furthermore, those participants also experienced an 11% reduction in LDL (bad) cholesterol and a 4% increase in HDL (good) cholesterol (30).

In another study, people with high blood pressure who took chlorella supplements daily for 12 weeks had significantly lower blood pressure readings, compared with the placebo group (31).

Similarly to chlorella, spirulina may benefit your cholesterol profile and blood pressure.

A 3-month study in 52 people with high cholesterol found that taking 1 gram of spirulina per day lowered triglycerides by about 16% and LDL (bad) cholesterol by about 10% (32).

In another study, 36 participants with high blood pressure experienced a 6–8% reduction in blood pressure levels after taking 4.5 grams of spirulina per day for 6 weeks (33).

Summary Studies have found that both chlorella and spirulina may help improve your cholesterol profile and reduce your blood pressure levels.

Both forms of algae contain high amounts of nutrients. However, chlorella is higher in omega-3 fatty acids, vitamin A, riboflavin, iron, magnesium, and zinc.

Though spirulina may be higher in protein, some studies suggest that the protein content in chlorella is comparable (21, 23, 24).

The high levels of polyunsaturated fats, antioxidants, and other vitamins present in chlorella give it a slight nutritional advantage over spirulina.

Additionally, much of the research on the health benefits of spirulina has been limited to animal studies.

The research on chlorella is more extensive. It includes animal and human studies, making the information on chlorella more reliable and applicable to people.

As with other supplements, it’s best to consult your healthcare provider before taking spirulina or chlorella, especially in high doses. This is particularly important because they may interact with certain medications, such as blood thinners (34, 35).

Additionally, consumers should only buy supplements from trusted brands to ensure their safety.

Summary Chlorella has a slight nutritional advantage over spirulina, as well as more evidence to support its health benefits.

Chlorella and spirulina are forms of algae that are highly nutritious and safe to eat for most people.

They are associated with many health benefits, including lowered risk factors for heart disease and improved blood sugar control.

Though chlorella is slightly higher in some nutrients, you can’t go wrong with either.