NOW Foods Spirulina, 500mg

Blue-green algae pressed into a 500mg tablet: NOW Foods keeps its Spirulina exactly that simple. The tablets are sold in three bottle sizes, 100, 200 and 500, which is a wider spread than most single-ingredient lines get.

NOW is a long-established American supplement maker with a reputation for plain-label, single-ingredient products, and spirulina is a natural fit for that approach. The 500-count bottle is the practical pick for anyone who has already settled on the product, while the 100-count keeps the entry price low.

All three sizes are listed together here at NE Commerce.