Phycocyanin
Specific molecules
The blue pigment of spirulina — a color no other food provides.
Destroyed by heat: cooked spirulina no longer provides it.
Effects and benefits
The blue of spirulina, one of the very few blue pigments in food, is also a protein. In meta-analyses of trials, spirulina lowered LDL cholesterol and triglycerides.
Spirulina is not a seaweed but a cyanobacterium, a bacterium that photosynthesizes. Its phycocyanin captures the orange light that chlorophyll lets through; extracted, it serves as a natural blue coloring in candy and ice cream.
A meta-analysis of seven trials found a drop in LDL cholesterol and triglycerides, and a rise in HDL, with 1 to 10 g of spirulina a day (Serban et al., 2016).
Contrary to a widespread idea, spirulina does not provide usable vitamin B12: it mostly contains an inactive form (Watanabe, 2007). And a tested spirulina is better: grown in poorly monitored water, it can contain toxins from other cyanobacteria (ANSES, 2017).
Sources: Serban et al., Clin Nutr, 2016 · Watanabe, Exp Biol Med, 2007 · ANSES, 2017