Chlorella. Nutrients, Quality and Applications

Chlorella is one of the best-known microalgae worldwide. While it is often marketed as a “superfood” for human consumption, it has so far played a comparatively minor role in animal nutrition. However, Chlorella vulgaris possesses several characteristics that make it of particular interest to feed developers. These include high crude protein content, natural pigments, as well as a range of vitamins and minerals.

What is Chlorella?

Chlorella vulgaris is a single-celled freshwater alga. Under feed legislation, it is classified as a dried algae product in accordance with Regulation (EU) No. 68/2013. Its defining characteristics include its intense green colour, resulting from its high chlorophyll content, as well as its high nutrient density.

The Chlorella offered by animalPro nutrition GmbH is supplied as a fine green powder with a mild aroma and flavour that is slightly reminiscent of seaweed. Despite its long-standing use in human nutrition, Chlorella is still used comparatively rarely in animal nutrition.

Analysis: More Than Just Protein

At first glance, the most striking feature of Chlorella is its high crude protein content. With 50 to 60 per cent crude protein, this microalga falls within a range that is unusual for plant-based feed materials.

However, the analysis shows that Chlorella is far more than just a source of protein.

Parameter	Chlorella vulgaris
Crude protein	50–60 %
Crude fat	10–15 %
Crude ash	5–9 %
Dietary fibre	10–15 %
Carbohydrates	17–22 %
Iron	100–120 mg/100 g
Chlorophyll	1,5–3 %
Carotenoids	0,5–1 %
Vitamin B12 (Analoga)	0,3–0,4 mg/100 g

In addition to its high protein content, Chlorella provides significant amounts of iron, magnesium, calcium, phosphorus, zinc, copper and selenium. It also contains various B-complex vitamins as well as vitamin K.

Particularly noteworthy are its high levels of chlorophyll and carotenoids. These natural pigments give the alga its intense green colour and distinguish it from many conventional feed materials.

It is precisely this combination of protein, micronutrients and pigments that makes Chlorella analytically interesting. A comparison with brewer’s yeast highlights this distinctive characteristic. Both raw materials provide significant amounts of protein and B-complex vitamins. In addition, Chlorella contains high levels of chlorophyll, carotenoids and iron, giving it a unique nutrient profile.

Protein Quality and Amino Acids

With 50 to 60% crude protein, Chlorella is among the most protein-rich plant-based feed materials. However, for nutritional evaluation, not only the quantity of protein is important, but also the composition of the amino acids it contains.

Studies show a broad spectrum of essential and non-essential amino acids. However, the exact composition may vary depending on origin, cultivation and processing. Therefore, crude protein content alone does not allow for a complete assessment of protein quality.

The Special Role of the Cell Wall

A frequently discussed aspect of Chlorella is its cell wall.

The Chlorella offered by animalPro nutrition GmbH is supplied with an intact, non-disrupted cell wall. Electron microscopy studies show that it consists of several layers and contains cellulose fibrils, among other components (Staehelin, 1966).

From a nutritional physiology perspective, the question therefore arises as to the extent to which the nutrients contained within the algal cell are accessible to the animal. There is no simple answer to this. On the one hand, the cell wall may influence the availability of individual components. On the other hand, Chlorella is harvested, dried and milled, which means that cell structures may already be partially damaged during processing.

Feeding trials in dogs also provide no evidence that Chlorella is fundamentally indigestible. The cell wall should therefore neither be regarded as an insurmountable barrier nor as irrelevant. Rather, it is a factor that may influence the availability of individual nutrients and should be taken into account when evaluating this feed material.

Vitamins, Minerals and Pigments

In addition to protein, Chlorella contains numerous other constituents. Particularly noteworthy are its levels of iron, magnesium, calcium, phosphorus, zinc, copper and selenium. It also contains various B-complex vitamins as well as vitamin K.

The available analyses also detect vitamin B12 analogues. However, their presence does not allow direct conclusions to be drawn regarding the amount of biologically active forms of vitamin B12.

Also noteworthy are the high iron levels of approximately 100 to 120 mg per 100 g. In a study involving rats with iron-deficiency anaemia, supplementation with Chlorella led to improvements in various blood parameters, including haemoglobin concentration, haematocrit and serum iron (Matsuura et al., 1991). These findings suggest that the iron contained is at least partially bioavailable.

Quality Criteria and Product Safety

Quality assurance plays a central role in the production of microalgae. In addition to nutrient content, potential contaminants and production conditions are of particular importance.

The Chlorella offered by animalPro nutrition GmbH is regularly tested for microbiological parameters, heavy metals and selected contaminants. The available analyses show low levels of lead, cadmium, mercury and arsenic. In addition, polycyclic aromatic hydrocarbons (PAHs), microcystins and β-methylamino-L-alanine (BMAA) are monitored.

The choice of cultivation system also influences the quality of the final raw material. The Chlorella offered is cultivated in greenhouse cultivation ponds. This method combines natural light conditions with a more controlled production environment compared with open outdoor cultivation systems.

Therefore, when evaluating Chlorella, not only nutrient content is relevant. Production conditions, quality assurance and the regular monitoring of potential contaminants are equally important.

Potential Applications

Depending on the formulation objective, this microalga can be used to supplement protein, micronutrients or natural pigments. It is used, among other applications, in complementary feed, functional formulations, and concepts for companion animals, horses, livestock and aquaculture.

In practice, comparatively small quantities are usually used. Availability, price, acceptance and technological requirements play just as important a role in the selection of the raw material as its nutrient profile.

Conclusion

Chlorella vulgaris is a versatile microalgal raw material with a high nutrient density. The combination of protein, micronutrients and natural pigments makes this alga analytically interesting.

At the same time, Chlorella demonstrates that the evaluation of a feed material should not be based solely on individual analytical values. Aspects such as cell wall structure, processing and quality assurance are just as important for practical assessment as the composition itself.

It is precisely this combination of characteristics that explains the continuing interest in Chlorella across different areas of animal nutrition.

References:

Staehelin, Andres. “The Ultrastructure of the Cell Wall and Chloroplast of Chlorella” (Die Ultrastruktur der Zellwand und des Chloroplasten von Chlorella). Zeitschrift für Zellforschung und mikroskopische Anatomie 74(3) (1966): 325–350.

Matsuura, E., et al. “Effect of Chlorella on Rats with Iron Deficient Anaemia.” The Kitasato Archives of Experimental Medicine 64(4) (1991): 193–204.

Cabrita, Ana R. J., et al. “Effects of Microalgae as Dietary Supplement on Palatability, Digestibility, Faecal Metabolites, and Microbiota in Healthy Dogs.” Frontiers in Veterinary Science 10 (2023): 1245790.

Cabrita, Ana R. J., et al. “Nutritional Composition and Untargeted Metabolomics Reveal the Potential of Tetradesmus obliquus, Chlorella vulgaris and Nannochloropsis oceanica as Valuable Nutrient Sources for Dogs.” Animals 12(19) (2022): 2643.