Spirulina

Greens powders are marketed as convenient alternatives to vegetables, but the evidence on their nutritional equivalence, bioavailability, and health outcomes is limited. This article reviews what greens supplements can and cannot replace.

Green powder supplements (spirulina, chlorella, wheatgrass, barley grass, kale powder) provide concentrated micronutrients and antioxidants but are not superior to eating whole vegetables. Spirulina has the best evidence base among common ingredients: protein content (60–70% by weight), antioxidant activity (Deng 2019), and a small RCT showing blood pressure reduction. No green supplement has EFSA-authorised weight loss or metabolism claims. Food is the reference standard; greens powders can supplement but not substitute.