From a BMJ Open Heart online study (March 8, 2020):
Overall, the evidence in the literature suggests that spirulina improves several well-established CVD risk factors including hyperlipidaemia and seems to provide benefits around weight loss.
Although caloric restriction and exercise are the mainstay treatments for obesity, spirulina has shown significant benefits in aiding weight loss. The phycocyanin in spirulina contains a light-harvesting chromophore called phycocyanobilin, which is capable of inhibiting nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase, a significant source of oxidative stress in adipocytes playing a key role in inducing insulin resistance and shifting adipokine and cytokine production in hypertrophied adipocytes. Thus, by suppressing adipocyte oxidative stress, spirulina may lead to systemic anti-inflammatory and insulin-sensitising effects.
Spirulina is both a salt and fresh water blue-green algae, which is being increasingly studied recently. Spirulina was initially classified under the plant kingdom due to its rich plant pigments and its ability to photosynthesize, but was later placed into bacterial kingdom (cyanobacteria) due to its genetic, physiological and biochemical makeup. Spirulina grows naturally in high salt alkaline water reservoirs in subtropical and tropical areas of America, Mexico, Asia and Central Africa.