Spirulina vs Chlorella: what to choose and for whom

Spirulina and chlorella compete for a place on the shelf of healthy-eating enthusiasts, but they suit different people and different goals. The editorial team has put together a practical guide: when spirulina makes sense, when chlorella does, when it is better to do without both, and how to check the quality of a product.

First decide why you need algae

Spirulina and chlorella are bought with the most varied intentions: "for immunity," "for detox," "as plant protein," "instead of multivitamins." Most of these expectations are either overstated or unsupported by science. So the choice between the two algae should start with a realistic goal, not with which of them is more popular on social media.

If your goal is additional support of the lipid profile against the background of healthy eating, there are more arguments on the side of spirulina. If you are looking for a green supplement with a milder taste and chlorophyll, chlorella is chosen more often. But if you need vitamin B12 or a significant amount of protein, neither alga will solve that task.

It is also worth assessing the budget. High-quality raw material with certificates for heavy metals and toxins costs more, and this is not the place to economize. A cheap product of unknown origin from either category carries greater risk than any potential benefit from it.

Finally, consider tolerability and convenience. Spirulina powder has a pronounced taste and color that not everyone likes, so many choose tablets. Chlorella in tablets is the most common format. However, for an equivalent serving of tablets you will have to swallow quite a lot.

Who is better suited to spirulina

Spirulina has the largest volume of research among "green" supplements. The meta-analysis by Serban and colleagues (2016) showed its favorable effect on total cholesterol, LDL and triglycerides. So it may be appropriate for adults who want to additionally support lipid metabolism together with a change in diet and physical activity, but not instead of medications prescribed by a doctor.

For endurance athletes spirulina is of interest because of data from the small study by Kalafati and colleagues (2010), where it prolonged time to fatigue and enhanced fat oxidation. This result should be regarded as preliminary: it gives no grounds to consider spirulina an ergogenic supplement on a par with caffeine or creatine.

Spirulina also makes sense for people who eat vegetables poorly and want to supplement their diet with carotenoids and antioxidant pigments. At the same time it does not replace a varied diet but only complements it.

Spirulina should be avoided by people with phenylketonuria, and in autoimmune diseases and when taking immunosuppressants - consult a doctor. For a cautious start, a small serving is usually recommended - about 1 g per day - with a gradual increase. In clinical studies doses from a few grams to about 10 g per day were used.

Who is better suited to chlorella

Chlorella is often chosen by those who dislike the taste of spirulina or who are looking for a product high in chlorophyll. Its evidence base is more modest: the review by Bito and colleagues (2020) describes mostly small studies with individual signals regarding immune, lipid and glycemic markers.

For vegans chlorella may be of interest because genuine vitamin B12 has been found in some samples. However, the content differs several-fold across products, so it cannot be relied upon as the sole source. A more reliable option is a separate cyanocobalamin or methylcobalamin supplement with monitoring of B12 levels in tests.

The key point for chlorella is the processing of the raw material. Choose a product with a mark about a broken cell wall, because otherwise absorption will be much worse. Also check the country of origin and the presence of tests for heavy metals: algae accumulate them from the growing environment.

Chlorella contains vitamin K, so people taking warfarin or other vitamin K antagonists need to consult a doctor - a change in intake of this vitamin affects the action of the drug. As with spirulina, it is worth starting with a small serving to assess the digestive reaction.

Practical choice by profile

To make the decision easier, the editorial team has summarized typical scenarios in a table. It does not replace individual consultation but helps to orient which supplement to consider first and when it is better to do without algae altogether.

For athletes in strength disciplines neither alga has an obvious place in the diet. A few grams of the supplement provide only a few grams of protein, whereas an athlete's daily requirement is measured in hundreds of grams. The money is better directed toward complete nutrition.

Combining spirulina and chlorella in one product is a common marketing move. There are no scientifically substantiated advantages of precisely such a combination, so it is worth buying a mix only when it is convenient and the quality is confirmed for both components.

Whatever the choice, assess the effect soberly. If after a few months of regular intake you notice no changes in tests or well-being, this is a normal result for a supplement with a moderate evidence base, not a reason to increase the dose.

Quality checklist before buying

The greatest risk of algae supplements is associated with contamination. The United States Pharmacopeia recognized spirulina as safe given proper quality (Marles et al., 2011), but the study by Roy-Lachapelle and colleagues (2017) detected cyanotoxins in some products on the market. So quality certificates are the main criterion of choice.

1. The presence of a certificate of analysis (CoA) for heavy metals: lead, cadmium, mercury, arsenic.
2. Testing for microcystins - especially important for cyanobacteria.
3. Microbiological purity and the absence of foreign algae.
4. For chlorella - a mark about a broken cell wall.
5. Transparent information about the country and method of cultivation.

It is worth avoiding products that promise "removal of toxins," "cure" of diseases or "replacement of all vitamins." Such wording indicates aggressive marketing rather than quality. A reliable manufacturer writes about composition and quality control, not about miraculous properties.

Algae should be stored in a dry, dark and cool place in a tightly closed package. Powder easily absorbs moisture and odors, and pigments are destroyed by light. If the product has changed color or smell or has caked, it is better not to consume it.

Editorial conclusions

Spirulina is the better choice if you are interested in supporting the lipid profile or want to try the supplement with the largest volume of research among algae. Chlorella is an alternative for those to whom a milder taste and chlorophyll matter, provided the cell wall is properly processed.

Neither of them solves the vitamin B12 problem for vegans and neither is a significant source of protein for athletes. From both, one should not expect a noticeable effect on strength, mass or results in sport.

The main rule of choice is the quality and transparency of the manufacturer. People with chronic diseases and those taking medications should consult a doctor before starting.

To better understand the differences between the algae, read our article "Spirulina or Chlorella: what is the difference," as well as articles on vitamin B12 in a plant-based diet and on antioxidants for athletes.

References

1. Serban MC, Sahebkar A, Dragan S, et al. A systematic review and meta-analysis of the impact of Spirulina supplementation on plasma lipid concentrations. Clin Nutr. 2016;35(4):842–851.
2. Kalafati M, Jamurtas AZ, Nikolaidis MG, et al. Ergogenic and antioxidant effects of spirulina supplementation in humans. Med Sci Sports Exerc. 2010;42(1):142–151.
3. Watanabe F, Yabuta Y, Bito T, Teng F. Vitamin B12-containing plant food sources for vegetarians. Nutrients. 2014;6(5):1861–1873.
4. Bito T, Okumura E, Fujishima M, Watanabe F. Potential of Chlorella as a dietary supplement to promote human health. Nutrients. 2020;12(9):2524.
5. Marles RJ, Barrett ML, Barnes J, et al. United States Pharmacopeia safety evaluation of Spirulina. Crit Rev Food Sci Nutr. 2011;51(7):593–604.
6. Roy-Lachapelle A, Solliec M, Bouchard MF, Sauvé S. Detection of cyanotoxins in algae dietary supplements. Toxins. 2017;9(3):76.