Harvard Women's Health Watch

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

Q. I read that spirulina is the next wonder vitamin. 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. Recently, it has experienced a surge in popularity as a dietary supplement. 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 its supposed health benefits.

Spirulina can grow in extreme conditions inhospitable to most other water-dwelling organisms. It's generally cultivated in manmade or natural lakes, harvested, and freeze-dried. Spirulina boasts a 60% protein content — it's a richer source of protein than most vegetables — and it's also a good source of beta-carotene, various minerals, and gamma linolenic acid, an essential fatty acid. Though spirulina is lauded as a source of vitamin B12 (used in making red blood cells), studies have shown that the B12 it contains isn't in a form that the body can use.

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