Algae are green, or "blue-green," freshwater, one-celled organisms that can be grown, dried, and safely used by our bodies. They have become available in the nutritional product arena as supplemental nutrients to enhance body functions only in the last couple of decades. Chlorella, spirulina, and blue-green manna are three of the main products produced from algae. Although they are not exactly the same, they are similar enough that I will discuss them together.
Spirulina made a big hit in the 1970s and has been the most popular algae product. Chlorella, however, was the first available to my knowledge and is still sold in many health food stores in a powdered or tablet form. Blue-green manna is more recent and usually harder to obtain.
All of these blue-green algae, or plankton products, have been used as "high-protein" nutrients that contain all the amino acids. They are considered a tonic and/or rejuvenator of the body and are used commonly during weight-loss programs or fasting. I have spoken with many people who have done a juice-spirulina powder fast and felt extremely well, with more energy than usual. Besides the high protein and low fat levels of these algae, they contain substantial amounts of vitamins and minerals and plant chlorophyll; spirulina was recently measured as rich in GLA, or gamma-linolenic acid, the oil found in the evening primrose plant.
It is possible that the GLA found in spirulina and possibly these other products accounts for some of the positive effects that people experience when using them, including decreased appetite, weight loss, and improved energy levels, especially mental energy. I personally have used all of these products and must say I have experienced a subtle increase in mental clarity and alertness (not like a nervous, caffeine-type stimulation). These algae must subtly stimulate our nervous systems or release certain internal neurochemicals that create this "up" feeling.
There has not been much medical research on any of these products, but I think there should be. When people find interesting substances from nature, I believe it is medicine’s duty to investigate the activity of these products so we can apply them effectively in our lives. Such analysis with herbs has brought us the whole field of pharmacognosy/pharmaceutical medicine, and perhaps continued analysis of nature’s potential remedies will bring useful new substances and help us to better integrate the drug and nondrug therapies.