Chlorella is an edible, single-celled plant (algae) that grows in fresh water. Over the past three decades, dried chlorella has become a popular dietary supplement (particularly in Japan) because of its impressive nutrient content. Each dried chlorella cell is 50 to 60 percent protein and contains the highest concentration of chlorophyll in the plant kingdom. Chlorella also contains high levels of essential vitamins, minerals, and other nutrients including beta-carotene, vitamins A, C, E, B-1, B-2, B-12 and K, niacin, pantothenic acid, folic acid, biotin, calcium, phosphorus, magnesium, iron, zinc, copper, selenium, PABA, nucleic acids, enzymes and fiber. Popular among strict vegetarians (vegans) because of its amino acid profile (8 essential amino acids, 19 total), chlorella is also one of the richest nonanimal sources of vitamin B-12. Normally, chlorella's tough, nondigestible cell wall would make its nutrients unavailable to the human digestive tract, but supplement manufacturers have developed processing techniques that break the cell walls, making the nutrients more accessible. This "broken cell wall" chlorella is considered the preferred form for supplementation.
Many people take chlorella as a general "system cleanser" to help remove heavy metals and other toxic compounds from the body. Animal studies indicate that components of chlorella's cell walls bind to certain toxins in the gastrointestinal tract, allowing them to be eliminated with the feces. In other studies, chlorella has demonstrated the ability to absorb cadmium, nickel, and a variety of other metals that can be toxic to the human body. Chlorella's high chlorophyll content may make it helpful for controlling breath and body odor as well.
Chlorella is a natural food with no known toxicity, however allergic reactions may occur in some individuals. At high levels of consumption, chlorella may cause gas, mild gastrointestinal discomfort, or diarrhea. Green coloration of stools is common, due to chlorella's high chlorophyll content. Chlorella is available in powder and tablet forms, and in chlorella-fortified foods. Water-soluble extracts of chorella known as "chlorella growth factor," which contain concentrated levels of amino acids and vitamins, are also available. Proper dosage of chlorella extracts should be indicated on the label.