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 of heart disease and improving blood sugar management (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
  • omega-3 fatty acids
  • provitamin A
  • riboflavin
  • magnesium
  • iron
  • zinc

Spirulina is lower in calories but still contains a high amount of:

  • riboflavin
  • thiamine
  • iron
  • 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’re 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 (8, 13, 14).

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 (15).

Both forms of algae contain various types of polyunsaturated fats.

However, 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, 6).

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.

Both are high in antioxidants

In addition to their high levels of polyunsaturated fat, both chlorella and spirulina are very high in antioxidants.

These are compounds that interact with and neutralize free radicals in your body to prevent damage to cells and tissues (16).

In one study, 52 people who smoked cigarettes were supplemented with 6.3 grams of chlorella or a placebo for 6 weeks.

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 (17).

Furthermore, those who received a chlorella supplement also showed a significant decrease in DNA damage (17).

In another study, 30 people with chronic obstructive pulmonary disease (COPD) consumed either 1 or 2 grams of spirulina daily for 60 days.

Participants experienced up to a 20% increase in blood levels of the antioxidant enzyme superoxide dismutase, and up to a 29% increase in vitamin C levels. (18)

Blood levels of an important marker of oxidative stress also decreased by up to 36%. (18)

Spirulina may be higher in protein

Civilizations as far back as the Aztecs have used algae, such as spirulina and chlorella, as food (1).

Due to its high protein content, NASA has used spirulina as a dietary supplement for their astronauts during space missions (19).

Currently, scientists are investigating chlorella as a potential high protein, nutritious food source for longer missions in space (20, 21, 22).

The protein found in both spirulina and chlorella contains all essential amino acids, and your body easily absorbs it (23, 24, 25).

While chlorella and spirulina both contain high amounts of protein, studies indicate that some strains of spirulina can contain up to 10% more protein than chlorella (23, 26, 27, 28).


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 management.

Exactly how this works is unknown, but several studies have indicated that spirulina may help increase insulin sensitivity in both animals and humans (29, 30, 31).

Insulin sensitivity is a measure of how well your cells respond to the hormone insulin, which shuttles glucose (blood sugar) out of the blood and into cells where it can be used for energy.

Furthermore, several human studies have found that taking chlorella supplements may increase blood sugar management and insulin sensitivity.

These effects may be particularly beneficial for those with diabetes or insulin resistance (32, 33, 34).


Some research shows that spirulina and chlorella may help lower blood sugar levels and increase insulin sensitivity.

Studies have shown that chlorella and spirulina have the potential to improve heart health by affecting your blood lipid composition and blood pressure levels.

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 (35).

Furthermore, those participants also experienced a 11% reduction in LDL (bad) cholesterol and a 4% increase in HDL (good) cholesterol (35).

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 (36).

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% (37).

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 (38).


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 slightly higher in protein, some studies suggest that the protein content in chlorella is comparable (23, 27, 28).

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

However, both offer their own unique benefits. One isn’t necessarily better than the other.

As with all supplements, it’s best to talk with 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 (23, 39).

What’s more, spirulina and chlorella may not be appropriate for people with certain autoimmune conditions.

If you have an autoimmune condition, speak with your doctor before adding chlorella or spirulina into your diet (40).

Additionally, consumers should only buy supplements from a reputable brand that has undergone third-party testing to ensure safety.


While both chlorella and spirulina are high in protein, nutrients and antioxidants, chlorella has a slight nutritional advantage over spirulina.

However, both are great choices.

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

They’re associated with many health benefits, including lowered risk factors for heart disease and improved blood sugar management.

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