By the way, doctor: Is spirulina good for you?

Q. I read that spirulina is good for your health. What can you tell me about it?

A. Spirulina — classified as a cyanobacteria, or blue-green algae — has been used for centuries as a food source in other countries. Spirulina is available in capsules, tablets, and powder and has been incorporated in certain foods and beverages such as energy bars, popcorn, and smoothies. An Internet search returns hundreds of suppliers from around the world promoting spirulina's supposed health benefits.