Spirulina (Blue-Green Algae) is widely promoted as a tonic supplement that can be taken regularly for general health. It contains iron and B12 as well as amino acids; its nutritive value is sometimes compared to that of the soybean. Spirulina is said to have blood cleansing, rejuvenating effect, and its touted as a low-fat, high protein supplement that can increase energy levels, enhance mental alertness, and help curb the appetite.

It is also said to boost the immune system, treat AIDS, and control Alzheimer's disease and diabetes mellitus.