Spirulina gives you more energy
Many users swear by it: spirulina gives them energy and banishes fatigue. A small human study that nutritionists published in the Journal of Food Sciences and Nutrition suggests that they may be right.
Spirulina & fatigue
So does spirulina get rid of fatigue? If you go in search of an answer in the scientific literature you'll find conflicting opinions. According to a Romanian study in which people with chronic fatigue symptoms were given three grams spirulina daily, the answer is no. [Phytother Res. 2007 Jun;21(6):570-3.] But there are a couple of studies in which runners took spirulina and found that it did have an effect. Read more about these studies here and here.
The researchers in this post decided to take another look at the mental and physical effects of spirulina on tiredness. They didn't look at the effects of spirulina on elite runners, nor did they take subjects with a fatigue syndrome, instead they looked at the effects of 17 ordinary healthy men aged between 20 and 43. Nine men were given 3 g spirulina in tablet form daily; eight men were given a placebo.
The researchers used spirulina manufactured by the American company Cyanotech. [cyanotech.com] Cyanotech also sponsored the study.
Less mental fatigue
The researchers got the subjects to fill in the Multidimensional Assessment of Fatigue questionnaire before starting supplementation , four hours after the first intake , and after eight weeks of supplementation . The figure below shows that just a few hours after taking their first dose of spirulina the subjects' scores had improved significantly. And after eight weeks the scores of the spirulina group had improved even more.
Less physical fatigue
Before starting supplementation , after one week  and after eight weeks  of supplementation, the subjects had to spend thirty minutes on a cross-trainer.
After a week of supplementation the subjects in the spirulina group expended significantly more energy than they had done at the start. That meant that they were able to do more in the same amount of time. After eight weeks of supplementation the spirulina group's calorie expenditure was still higher than before supplementation started, but the difference was no longer statistically significant.
"In summary, this study showed anti-fatigue effects for both short term and long term spirulina intake", the researchers concluded. "Future work can examine larger subject numbers, other testing methods, and females."
Int J Food Sci Nutr. 2016 Mar;67(2):203-6.
Spirulina boosts runners' performance 26.01.2010
Spirulina gives runners more stamina 18.11.2008