Blue-green algae isn't algae, it's a photosynthetic bacteria. Quite a few kinds are toxic but assume they aren't in the supplements!

There are supplements made from Chlorella, a true green alga, from Martek corporation which include essential fatty acids (DHA & EPA). These are often used by people who don't want to take fish oil capsules. However there is no good evidence that these fatty acids protect against cancer, according to a news report I read today. Good for your cholesterol and important in nerve development and functioning, however.

Btw, the algae are the initial source of the DHA and EPA which end up -- going up the fod chain -- in marine fish.

Gail