Chlorella vs. Spirulina: Which One Is Right for You?

People are buzzing about chlorella and spirulina. With miraculous-sounding benefits, it’s no wonder the algae biz is booming. Sales of spirulina are expected to jump by as much as 10.5 percent by 2026, and sales of chlorella are expected to increase by 7 percent between 2020 to 2025. But do these popular supplements live up to the hype? And which one is the better choice? Let’s take a look.

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What is chlorella?

Chlorella is a freshwater alga native to Japan and Taiwan. Although it is rich in protein, fibre, and a variety of vitamins and minerals, the hard cell wall of this algae cannot be digested by humans. The only way to gain the nutritional benefits from chlorella is to ingest it in supplement form. Chlorella supplements can be found on shelves as powders, capsules, or tablets.

The health benefits of chlorella

With its rich nutritional profile, chlorella may offer many potential health benefits. “As a plant-based protein, chlorella provides about 50 to 60 percent complete protein, including all nine essential amino acids and many of the B vitamins, along with being a great source of vitamin A, iron, and zinc,” says Sarah Koszyk, a registered dietitian nutritionist and author of 365 Snacks for Every Day of the Year.

This is especially great news for those who follow a vegan diet. It can be challenging to meet the daily nutrition recommendations for nutrients such as vitamin B12 without consuming animal products. The amino acid profile of this algae is responsible for many of its health benefits. “Chlorella products contain a large amount of the amino acid arginine, which is imperative for the production of nitric oxide,” explains Lindsay Allen, a registered dietitian nutritionist and owner of Back in Balance Nutrition & Fitness. “A lack of nitric oxide is associated with heart disease, diabetes, high blood pressure, and sexual dysfunction.”

This benefit of chlorella may explain some of the health claims associated with the supplement. Research has found that chlorella supplements may help to lower cholesterol levels and improve immune function, blood pressure, and blood sugar levels. In addition, chlorella may aid the body’s own detoxification process. “Chlorella has been shown to bind to heavy metals and toxins in the body and actually help flush them out,” says Koszyk, who is also co-founder of wellness company MIJA, which sells a supplement that includes chlorella.

(Related: 15 Cleansing Foods to Detox Your Body Naturally)

What is spirulina?

Spirulina is a blue-green alga that grows in both freshwater and saltwater. Incredibly nutrient-rich, just one tablespoon provides four grams of complete protein. It’s also an excellent source of copper, a good source of iron, and has the B vitamins thiamine and riboflavin. In fact, this tiny algae has even been used by NASA to fuel the nutrition of astronauts. Spirulina supplements are increasingly popular for good reason.

“Spirulina is full of immune-boosting vitamins and minerals as well as being one of the highest protein-containing vegetables—with about 60 percent protein content,” says Elizabeth Gunner, a registered dietitian nutritionist. Unlike chlorella, spirulina can be digested in a whole food form and can be incorporated into the diet as an ingredient or as a nutritional supplement.

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The health benefits of spirulina

Because spirulina is so nutrient-dense, it can provide many health benefits when you eat it regularly. “Spirulina contains antioxidants such as phycocyanin, which is anti-inflammatory, immune-supporting, cancer reducing, and brain supporting,” says Koszyk. Research has also found that spirulina may help reduce cholesterol and triglyceride levels and improve blood glucose levels.

Spirulina supplements have also increased in popularity among athletes, thanks to the potential impact they may have on exercise-induced oxidative damage. “Spirulina may offer a positive effect on athletic endurance by reducing oxidative stress, which increases the ability to train harder and longer,” explains Koszyk.

Chlorella vs. spirulina

Both spirulina and chlorella supplements may offer benefits to overall health, but is one superior? “Both show very similar benefits in terms of the bioactive compounds that affect our physiology,” says Allen. However, there are a few key differences between them. “Chlorella is higher in fat and calories when compared to spirulina, but spirulina may contain up to 10 percent more protein than chlorella,” explains Koszyk. And the differences aren’t in the macronutrients alone. “Chlorella does appear to contain higher amounts of vitamins and minerals, especially selenium, vitamin D2, and B12,” Allen says.

The downside of chlorella and spirulina

Although these two nutritional powerhouses offer many benefits, there are a few downsides to consider. “Although uncommon, some individuals may experience gas or nausea with chlorella supplements,” says Koszyk. Spirulina’s negatives are more significant. “Depending on where the spirulina is grown, there could be toxins and heavy metals found within it, which is why finding a reliable source is important,” says Koszyk. It is also important to note that some people can experience an allergic reaction to algae and therefore would need to avoid supplementation with either chlorella or spirulina.

(Related: Why You Need to Talk to Your Doctor Before Taking Supplements)

A personal choice: chlorella vs. spirulina

Based on the research surrounding these supplements—along with their nutrition profiles—both can provide benefits to health. Which is best for you may come down to your personal needs and goals. Talk to your health care provider before taking a new supplement. A physician or registered dietitian can help guide your decision.

When choosing a supplement, always be sure to select a high-quality brand. Purchase from trusted vitamin brands and check the label to be sure the product has been tested by an independent third party. “Since supplements are not FDA [Food and Drug Administration] regulated, I recommend consumers purchase supplements that are third-party tested,” says Gunner.

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