Chlorella vs. Spirulina: Algae Health Facts from a Dietitian

Should these algae powders play a bigger role in your diet? Learn about chlorella and spirulina’s potential health benefits and side effects.

By Rachel Gargano, MS, RD, CSSD, CBS

— On Mar 12, 2025

Chlorella vs. Spirulina: Algae Health Facts from a Dietitian

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From pills to powders to tablets, chlorella and spirulina supplements are advertised to be impressive, but are they really worth adding to the diet? As a registered dietitian, my answer is a resounding yes!

I love it when nutrient-dense, power-packed foods come to the forefront like this. Both chlorella and spirulina are rich in micronutrients, antioxidant content, and bioactive phyto-compounds, making them excellent additions to the diet. But what a lot of people don’t know is that there are key differences in their nutrient profiles that make one slightly better than the other.

Read on to learn more about chlorella and spirulina to see which one has the edge and whether adding them to your daily routine would help meet your individual goals.

Chlorella and Spirulina at a Glance

Overall, the nutritional quality of spirulina and chlorella are relatively equal, with a few fundamental distinctions.

	Spirulina	Chlorella
Nutritional facts (per ounce)	Protein: 16 grams Carbs: 7 grams Fat: 2 grams	Protein: 16 grams Carbs: 7 grams Fat: 3 grams
Key micronutrients	Vitamins B1, B2, B3 Copper Iron	Vitamins A, B12, B2, C Iron Magnesium Zinc
Supplement form	Powder, tablets, pills, in a greens powder blend	Powder, tablets, pills, in a greens powder blend
Types of fats	Higher in omega-6	Higher in omega-3s
B12 availability	Inactive / pseudo B12	Mostly bioactive B12
Primary antioxidant	Phycocyanin	Chlorophyll
Habitat & species	Salt or freshwater cyanobacteria	Freshwater green algae

What Is Chlorella Powder?

Chlorella is a freshwater microalga. This single-celled plant is high in chlorophyll, a powerful antioxidant that gives chlorella its naturally vibrant green hue.

While rich in micronutrients and bioactive compounds, chlorella has a strong cell wall made of fibrous cellulose that we cannot break down during digestion. For this reason, it’s important to find a chlorella supplement in which the cell walls have already been mechanically broken down. Look for either ‘broken cell wall’ or ‘cracked cell wall’ chlorella so your body can extract the most nutrition from it.

Chlorella contains more micronutrients than spirulina, including vitamin C, vitamin A, B2, iron, phosphorous, and zinc. And while these algae contain the same amount of carbohydrates, chlorella contains more fat and omega-3 fatty acids, an incredibly important macronutrient.

Dietitian note: While chlorella contains unsaturated fats with a high percentage of omega-3 fatty acids, we can only benefit if we consume a fairly high daily dose.

Chlorella Pros

Rich in over 400 types of carotenoid antioxidants
Packed with vitamins and minerals
Contains bioactive vitamin B12
Higher dose of omega-3 fatty acids
Contains all essential amino acids

Chlorella Cons

Strong cellular walls must be mechanically broken down before human ingestion
May cause an allergic reaction in some people

What Is Spirulina Powder?

Spirulina is a multicellular plant that grows in both fresh and saltwater. While many confuse it for algae, spirulina is actually a spiral-shaped cyanobacteria. Because of its potent blue-green color, imparted by the antioxidant phycocyanin, many still refer to this plant as a saltwater blue-green alga.

This ancient plant has quite a storied history, with records of it being consumed by the Aztecs as well as sent to space as a fundamental part of the astronaut’s daily nutrition.

While chlorella may include higher amounts of micronutrients, spirulina contains significantly more copper and a bit more B1. Unlike chlorella, spirulina’s cell walls are not made of cellulose, making it much easier to digest.

Spirulina Pros

Antioxidant-rich
May contain more protein than chlorella
Contains ample micronutrients

Spirulina Cons

Contains mostly pseudo vitamin B12
Needs to be third-party tested for purity
May cause an allergic reaction in some people

Potential Health Benefits

Chlorella and spirulina are ripe with possible benefits. In fact, since these two plants are so similar, they share many of the same health advantages.

Benefit #1: Antioxidant-Rich Profiles

These two algae are rich sources of phenolic compounds, which have anti-inflammatory properties and help support our immune system.

Antioxidants are powerful substances that help protect our cells from damaging free radicals. Getting enough of these in our diet helps with inflammation and plays a role in keeping the human body humming healthfully along.

Spirulina is particularly high in phycocyanin, a protein that also acts as a potent antioxidant. Not only does this blue-green algae help with inflammation, but it has also been shown to help impair the growth of harmful bacteria in the gut, playing a positive role in our digestive health.

Chlorella has several antioxidants that contribute to its anti-inflammatory prowess, including chlorophyll and lutein. Chlorophyll is best known for its ability to convert sunlight to energy for plants, but it also has anti-inflammatory properties that can help with oxidative stress in the body.

Benefit #2: Heavy Metal Binding

Heavy metals in foods are a hot topic right now. It turns out that metals are naturally found in air, soil, and water because they are naturally part of the Earth’s crust. Unfortunately, pollution, farmyard manure, sewage sludge, and certain fertilizers also introduce these metals into the environment.

Interestingly, both chlorella and spirulina contain compounds that bind to heavy metals and may help the body’s natural detoxification pathways.

Additionally, chlorella may help promote the excretion of other chemicals, such as dioxins.

Benefit #3: Performance and Recovery

While it’s a priority for top athletes to get the most out of their workout and enhanced recovery, even weekend warriors can greatly benefit from these types of support. And while more research is needed, chlorella and spirulina may be beneficial in performance:

Research indicates that chlorella may improve both aerobic and anaerobic exercise performance, help with fatigue, and facilitate recovery.
As for spirulina, studies signal that it may impact strength and power performance, aerobic fitness, and accelerate recovery.

Bonus Benefit of Chlorella: Bioactive Vitamin B12

Vitamin B12 has important functions in the body, including forming red blood cells and nervous system cells and helping to make DNA.

Most bioactive B12 is found in animal proteins such as beef, fish, and poultry, while plants mostly contain inactive (aka pseudo-vitamin) B12, which cannot be used by the body. This is true of spirulina; however, recent studies indicate that chlorella contains mostly bioactive B12 in the form of methylcobalamin.

Interestingly, there is a theory that pseudo-vitamin B12 competes to be transported with methylcobalamin and other forms of active B12. Yet, research demonstrates that our B12 transporters have a higher affinity for bioactive B12 than pseudo-B12, which means they are much more likely to bind to and absorb bioactive B12.

This preferential binding may only be affected if someone consumes very high doses of pseudo-vitamin B12.

Potential Side Effects

For the most part, it is safe to take chlorella and spirulina. With that said, it’s always important to review any potential side effects and discuss any new supplements with your primary care provider before adding them to your daily routine. Here are the primary side effects that may be linked to these algae

Digestive Upset

As with any ingredient that our body may not be familiar with, digestive upset could be a symptom experienced when first introducing spirulina and chlorella. While uncommon, some people may feel nausea, gas, or abdominal discomfort.

Rare Allergic Reactions

Some of the proteins in both spirulina and chlorella show sequencing similar to known allergens. While an allergic reaction to one of these plants is fairly rare, some people who already have allergies may want to proceed with caution, as they may be more susceptible to a possible allergic reaction.

Should you experience any symptoms of an allergic reaction, such as hives, rash, itchy water eyes, runny nose, vomiting, and difficulty breathing, stop taking the supplement immediately and seek medical attention.

Interactions with Medications

Both chlorella and spirulina contain about 20 to 30% of your daily recommended dose of vitamin K. This vitamin helps with blood clotting, and too much may interfere with blood thinning medications.

While these plants do not contain as much vitamin K as other leafy greens, it’s always important to check with your primary care provider before adding more of this vitamin into your daily routine if you currently take an anticoagulant.

Spirulina Contains Phenylalanine

This may not mean much to most people, but those with a metabolic disorder called Phenylketonuria (PKU) may need to avoid spirulina. Phenylalanine is an amino acid used in the formation of proteins. For most people, this compound is harmless, but those who cannot break it down need to avoid foods that contain too much.

How to Use Chlorella vs. Spirulina

If you’ve decided that one or both supplements are for you, the next step is figuring out how to take it.

Dosing

Currently, there is not enough information to recommend a specific daily dose for either spirulina or chlorella, but here are preliminary guidelines:

Chlorella: Most research dosed in the range of 6 to 10 grams per day
Spirulina: Most research dosed in the range of 2 to 10 grams per day

Keep in mind that everyone has different needs and tolerance levels. Starting low is always recommended to understand how your body responds to a new supplement. I usually recommend 1 to 3 grams daily to my clients to help add quality nutrients and phyto-compounds to their diet.

Dietitian Tip: When taking a commercial supplement, always follow the recommended dosing on the package.

How to Consume

In general, spirulina tends to have a stronger seaweed-esque flavor with a grainier texture, while chlorella has a milder, grassy flavor that is usually ground more finely due to being mechanically broken down. Be sure to choose broken or cracked cell wall supplements in order to experience chlorella’s potential benefits.

Though also found in tablets or pills, the most popular way to consume spirulina and chlorella is in powder form, added to:

Smoothies or juice
Yogurt or oatmeal
Baked goods

The great news is that you don't have to hunt down these algae only at health food stores, as many greens powders include a decent amount of spirulina or chlorella. This allows for a tastier vehicle to take these two powerful supplements. Greens powders also provide a way to boost overall dietary nutritional content.

No specific time of day is recommended to consume spirulina or chlorella. Since consistency is the most important factor, take it when you’re most likely to remember!

Why I Recommend Algae-Rich Super Greens Powder

While both micro-algae are excellent ways to support overall health, chlorella has a leg-up with bioactive B12, more micronutrients, omega-3 essential fatty acids, and a slightly mellower flavor than spirulina. I see the benefit in adding both alga powders to your diet.

As a dietitian, my favorite way to take my daily doses of chlorella and spirulina is in Live it Up Super Greens. While Super Greens is dense in both of these, it contains three times as much chlorella, which allows for even more advantages.

Not only do I know that I’m getting quality nutritional benefits from spirulina and chlorella, but also from over 20 other nutritious superfoods, from grasses to herbs and vegetables. As someone who suffers from gut issues, I really like how Super Greens contains 5 billion CFU probiotics, 3 digestive enzymes, and 3 grams of fiber.

Plus, with all the research I’ve done on greens powders and the benefits of vegetables in our daily diet, I know that Live it Up Super Greens meets my high expectations for a supplement by being made with all organic vegetables, being third-party tested and GMP-certified, and having dosing that gives me confidence.

Frequently Asked Questions

Learn more about these potent superfoods with the FAQs below.

Which is better, chlorella or spirulina?

While both algae are high-quality sources of antioxidants and support immune function, chlorella has slightly better nutritional properties. This freshwater green alga contains more omega-3 fatty acids than spirulina, has higher vitamin and mineral content, including excellent amounts of beta carotene and bioactive B12, and is rich in many antioxidants to help fight free radicals.

Should you take spirulina and chlorella together?

While it’s not necessary to take spirulina and chlorella together, these superfood algae can work together with their impressive nutritional profiles. These plants are complete proteins, containing all the essential amino acids, and have a high overall protein content. Their antioxidants and micronutrients are also complementary. Many greens powders like Live it Up Super Greens offer chlorella and spirulina in their formulas to help you feel the impact of both superfoods on your well-being.

What toxins does chlorella remove?

Research shows that chlorella may bind to heavy metals, some radioactive isotopes, and even certain toxins such as dioxin. Binding to these metals and toxins may promote their excretion from the body and help support detoxification.

Do chlorella and spirulina help with weight loss?

While chlorella and spirulina may not help directly with weight loss, taking them as part of an overall balanced and whole foods-based diet may help support weight management.

Both plants contain all the essential building blocks to produce protein in the body, and getting enough quality protein can help you stay more satisfied and cravings-free. Additionally, adequate amounts of antioxidants that fight free radicals and inflammation may be key to supporting a healthy metabolism.

Who should not take spirulina?

Though spirulina offers numerous potential benefits, the blue-green alga contains proteins that may be allergenic, so people who have allergies may need to take spirulina with caution. It also contains about 20 to 30% vitamin K, which may interfere with certain medications such as blood thinners.

People who are breastfeeding or pregnant should consult their doctors before taking spirulina. Always discuss supplement use with your health care provider before adding them to your diet.

Is chlorella hard on the liver?

Research indicates that taking chlorella generally has no effect on alanine aminotransferase (ALT) or alkaline phosphatase (ALP) levels and may actually lower aspartate aminotransferase (AST) levels. This means that chlorella likely has no harmful effects on the liver when taken in moderate doses, but rather may prove beneficial for liver function. Still, be sure to follow product guidelines when taking any chlorella supplement.

References

About the author:

Rachel Gargano, MS, RD, CSSD, CBS

Rachel is a registered dietitian based in Contra Costa County, California, with over 15 years experience. She specializes in whole-body wellness and plant-based nutrition, helping people understand the dynamic interplay between food and health so they can live life to the fullest. When not helping others, she enjoys spending time with her kids, being physically active, and tending to her abundant household plants.

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Chlorella vs. Spirulina: Algae Health Facts from a Dietitian

Chlorella and Spirulina at a Glance