Is green algae safe?

The potential hazards of green algae in topical application.

Few, if any, studies have been conducted on the exploration of potential dangers of using green algae on humans. Overall, these organisms are safe to use. However, some points can be clarified. Due to the lack of scientific data on the subject, we cannot assert whether the topical application of green algae could pose problems.

However, a concern could arise from their potential comedogenicity. Indeed, algae in general may pose a risk of comedogenicity. They would penetrate the pores and accelerate the growth of micro-comedones. It is nevertheless important to note that comedogenicity is not an exact science.

• No study has demonstrated a comedogenic effect of green algae specifically;

• Most of the green algae found on the market are used in the form of extracts, far too small to be able to "block" the pores;

• What is "comedogenic" for one person may not necessarily be so for another;

• The fact that an ingredient is considered comedogenic does not automatically mean that the product containing it is also comedogenic.

The potential hazards of consuming green algae orally.

In terms of their oral consumption, studies conducted on the subject have shown no toxicity of green algae. The administration of chlorella powder (a type of green algae) to mice has demonstrated no toxicity, nor any adverse effects that could compromise its use as a nutraceutical and/or dietary supplement.

We can, however, mention a few concerns. Algae in general are rich in iodine, posing a risk of irritating the pores and triggering inflammation when consumed in large quantities (beyond 1.1 mg per day). However, the green algae found in dietary supplements are often freshwater algae such as chlorella.

These only contain between 0.02 to 0.07%. Green algae capsules contain approximately 250 mg of algae, thus the iodine content would be around 0.05 mg per capsule. Given that the recommended daily dose of iodine for an adult is 150 mg, the content of green algae dietary supplements remains well below the limits and should not present any particular concerns.

Caution nonetheless to those intolerant to iodine. Discuss it with your doctor if this is your case.

Another point to consider is that chlorella could potentially cause photosensitisation risks when taken orally. This is a hypersensitivity to sunlight that manifests as skin redness or itching, for example. Studies have identified the photosensitising agent in chlorella as being the pheophorbide-a.

Pheophorbides are formed from the degradation of chlorophyll by chlorophyllase, naturally contained in chlorella. It allows certain wavelengths of visible light to penetrate the skin to the dermal blood vessels and cause vessel damage. However, photosensitive reactions are very rare.