Blue-green algae is a pretty niche ingredient. So you may be surprised to learn that the two main types of blue-green algae we consume, chlorella and spirulina, which look and taste interchangeable, are, in fact, entirely different foods. They’re both full of antioxidants, are incredibly nutrient-dense, and are sold in every form, from green drink mixes to gummies. But the similarities between chlorella and spirulina end there, as the two algae offer different nutrient profiles. So, which is better? We’ll lay out the facts for you.
Spirulina has been used as a food source in Mexico and Africa since approximately 1300 AD. According to Gaia Herbs, a leading herbal supplement brand, "the Aztecs harvested Arthrospira from Lake Texcoco and used it to make a sort of dry cake called tecuitlatl." The brand notes that it is likely the use of spirulina as food in Chad dates back to the same period or even earlier, to the Kanem Empire (9th century AD). In Chad, spirulina remains an important part of the local economy. On the Gaia Herbs website, it states: "It is still harvested and processed by hand into cakes known locally as dihe, for use in a sauce for meat and fish called la souce. It is an important part of their local economy, allowing the women of the village who harvest and process the dihe a certain amount of independence."
Chlorella, on the other hand, was discovered much more recently. Though it’s believed to have existed on the planet for billions of years, sources indicate "it was not until the microscope was invented after the 19th century that chlorella was first discovered." Dutch microbiologist Dr. Beijerinck is credited with discovering it in 1890, and it was then named chlorella.
Chlorella has a tricky situation with its cell walls, impacting its ability to gain the same mainstream popularity as spirulina. To process spirulina for consumption, algae is cultivated in ponds, harvested through filters, pressed, and dried. The drying process occurs both in the sun and indoors. From there, it’s ready to eat. For usage in fine applications like capsules, it is ground into a fine powder.
The process to harvest and package chlorella is mostly similar, but it has one major step that changes things. Where spirulina is bioavailable and safe, as is in its natural dried form, chlorella requires its cell walls to be cracked and pulverized. You may notice that any chlorella products you’ve purchased state "open-cell" or "cracked cell" clearly on the label. That’s because chlorella isn’t safe to eat without that being done. Since it was initially sold without including that part of manufacturing, that impeded its ability to hit the mainstream.
Without cracking its cell walls, consuming chlorella makes you overly sensitive to sunlight. "In the 1970s, chlorella was a huge hit in Japan, but the boom ended because of photosensitivity incidents caused by chlorella," retailer Yaeyama Chlorella notes on its website. "The photosensitivity incidents refer to occurrences of blisters caused by exposure to direct sunlight after ingestion of chlorella. Because chlorella has a tough cell wall indigestible by stomach acids, chlorophyll remains intact in the body. Therefore, there is a risk that the chlorophyll in the body will react with sunlight and cause blisters."
Now that all chlorella has its cell walls broken down in processing, this is a non-issue. But it does explain why spirulina has steadily grown in popularity while chlorella lags behind.
The Nutritional Profiles
While both chlorella and spirulina are full of protein and numerous antioxidants such as carotenoids and phenolic compounds, their nutritional profile similarities end there. Chlorella outperforms spirulina in a variety of ways.
Per one-ounce serving, chlorella has nearly 300% of the recommended dietary allowance (RDA) of vitamin A; spirulina has 3%. In addition, chlorella has 202% of the RDA for iron to spirulina’s 44%; 133% of your daily zinc to 4% of it; and 25% of the RDA for phosphorus versus 3%.
Spirulina does contain copper, which chlorella does not, weighing in at 85% of the RDA for that mineral, and it also has slightly more vitamin B1. The two are equal (or nearly so) in protein, vitamin B2, folate, carbs, and magnesium. Each contains all nine essential amino acids, a rarity for a vegetarian food source. Chlorella also contains more omega-3.
The Detoxifying Abilities
Because of their antioxidants, both chlorella and spirulina can assist with chelating. That means they can bind to and remove heavy metals that get trapped in our bodies, particularly in our blood. Both algae have been proven effective at detoxifying everything from aluminum to cadmium.
There’s no need for an either/or take on the topic. Both Spirulina and chlorella can be used in very high doses for heavy metal detox, binding toxins and purging them from the body, often without the common side effects of detoxification.
Blue Spirulina: Algae Made Pretty
The glorious health benefits of spirulina and chlorella can’t be overstated, but there is no contesting the fact that they are visually unappealing. Its green hue isn’t vibrant like matcha, or even deep and rich like kale or spinach.
Enter blue spirulina, an antioxidant extractive of spirulina. It’s "unicorn food" incarnate, and it’s what has enabled natural food manufacturers to color foods blue for the first time. That said, it’s an extractive, meaning that it offers some of the benefits of blue-green spirulina, but it’s nowhere near as nutritionally robust.
Which Is Better?
Both chlorella and spirulina are full of protein, amino acids, and antioxidants, and both are effective chelators. In addition, they each offer a good amount of assorted vitamins and minerals.
Outside of the visual appeal of blue spirulina extract, though, chlorella has a definite edge over spirulina when it comes to blue-green algae and the health benefits of this food group. The things it contains more of, like iron, omega-3, and zinc, are vital nutrients we all need in our diets. The only thing spirulina has a boost of over chlorella is copper, which is rare to be deficient in.
As a nutritionist, I'd recommend opting for chlorella. It offers a better bang for your buck, especially because the two are similarly priced. Spirulina is more commercially available, though, and I haven’t heard about anyone whipping up any chlorella gummies yet. So, if that’s the only form of algae you consider to be palatable, by all means, go that route. Any quantity we consume of blue-green algae is better than none, and with how nutrient-dense they both are, they’re both worth eating regularly.
Bito T, Okumura E, Fujishima M, Watanabe F. Potential of Chlorella as a Dietary Supplement to Promote Human Health. Nutrients. 2020;12(9):2524. doi:10.3390/nu12092524
Ramanan R, Kim BH, Cho DH, Oh HM, Kim HS. Algae-bacteria Interactions: Evolution, Ecology and Emerging Applications. Biotechnol Adv. 2016;34(1):14-29. doi:10.1016/j.biotechadv.2015.12.003
Sears ME. Chelation: Harnessing and Enhancing Heavy Metal Detoxification-- A Review. ScientificWorldJournal. 2013;2013:219840. doi:10.1155/2013/219840