Spirulina is a blue green micro algae considered a “superfood ” because of its nutrient profile. Spirulina is a complete protein, and contains several B vitamins, including B1, B2, and B3, and iron. Keep in mind, spirulina has a potent smell and flavor, so most people only add 1 or 2 tsp to a beverage or smoothie, so the values of the vitamins will be low with a low intake. On the market now are many spirulina supplements in higher dosages which can provide more of the nutrients.
Spirulina has many studies showing its benefits. Spirulina taken in high dosages has been shown to reduce oxidative stress, and to lower total cholesterol and LDL cholesterol (3). Oxidative stress, is when free radicals damage or “oxidize” cells. Oxidize means when a cell loses one electron, and this makes the cell unstable. Oxidative stress is the cause of many diseases.
Spirulina extract in lab animals was shown to inhibit the flu virus (1) , has been shown in trials to help the immune system in HIV patients (2)
Keep in mind, in all of the studies, patients were taking a high dosage of spirulina, coming from supplements rather than a small dosage that you might add to your smoothie.