Is green algae polysaccharide a ‘green path’ to health?

There is an increased interest in green algal polysaccharides as they have displayed many beneficial bioactivities. Relevant bioactivities found include promotion of gastrointestinal health, antioxidant, anti-inflammatory, immunomodulatory, anti-hyperlipidaemia, anti-osteoporotic, hypoglycaemic and anti-ageing. Among the many green algae species, the polysaccharides from the three main groups of green algae are more commonly studied. Namely, green algae from the Ulvales order, the Bryopsidales order and the Chlorella genus. As such, this review starts by providing a background on the popularity of these three groups of algae and introducing the basic structures of some of their polysaccharides. Polysaccharides extracted from green algae that have exhibited bioactivity that might make them a great nutraceutical are then highlighted. The current lack of comparisons between the effects of whole algae (which is popularly used as a health supplement, especially for Chlorella species) and polysaccharide extracts is also mentioned, which could hamper progress towards using green algal polysaccharide extracts instead of whole algae. Finally, the possible advantages of polysaccharide extracts as compared to whole algae are mentioned, one of which is the possibility of fine-tuning the dose that is not achievable by taking whole algae supplements due to the possible toxicity when taking whole algae at high levels.