An attempt to induce an immunomodulatory effect in rowers with spirulina extract. by Artur Juszkiewicz et al. Journal of the International Society of Sports Nutrition (2018) 15:9

Background: The aim of this study was to analyze the response of selected components of the immune system in rowers to maximal physical exercise, and to verify if this response can be modulated by supplementation with spirulina.
Method: The double-blind study included 19 members of the Polish Rowing Team, receiving 1500 mg of spirulina for 6 weeks, or a placebo.
Conclusion: The results of this study imply that supplementation with spirulina extract may protect athletes against a deficit in immune function (especially, anti-infectious function) associated with strenuous exercise, and may cause a beneficial shift in “overtraining threshold” preventing a radical deterioration of immunity.