Spirulina is known as a nutrient-dense food as it is packed full of vitamins, including vitamins A, C, E and B vitamins, as well as a whole host of minerals such as calcium, magnesium, zinc and selenium. You can add it to smoothies, which gives the drink a green color, or sprinkle it on salads or in soups, mix it into energy balls, along with other healthful ingredients or stir a tablespoon into fruit or vegetable juices.