Spirulina is a blue-green alga sold as powder or tablets, rich in protein and pigments.
Calculator Official intake Study doses Best form Safety Sources
This is not an essential nutrient, so there is no official daily intake. Only study doses are shown.
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
1-8 g a day
A meta-analysis of 5 trials (230 people, 1 to 8 g a day for 2 to 12 weeks) found systolic pressure about 4.6 mmHg and diastolic about 7 mmHg lower, mostly in people with high blood pressure.
No single dose
A meta-analysis of 7 trials found lower total and LDL cholesterol and triglycerides. The effect did not depend on the dose.
No best form
Why: Trials used spirulina powder or tablets. Do not count on it for vitamin B12.
Not a normal food in most diets.
Ask your doctor if you take medicines that suppress the immune system.
Spirulina is not a reliable B12 source: the B12-like compound in spirulina tablets was mostly an inactive form. Vegans need a real B12 supplement.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.