From www.webmd.com :
A type of algae that grows in fresh water. The whole plant is used to make nutritional supplements and medicine.
Most that is available in the U.S. is grown in Japan or Taiwan. It is processed and made into tablets and liquid extracts. These extracts contain “chlorella growth factor,” which is described as a water-soluble extract containing chemicals including amino acids, peptides, proteins, vitamins, sugars, and nucleic acids.
Be aware that products can vary significantly depending on the way “the crop” used to make them was cultivated, harvested, and processed. Investigators have found that dried preparation of chlorella can contain from 7% to 88% protein, 6% to 38% carbohydrate, and 7% to 75% fat.
As a medicine it is used for preventing cancer, reducing radiation treatment side effects, stimulating the immune system, improving response to flu vaccine, increasing white blood cell counts (especially in people with HIV infection or cancer),preventing colds, protecting the body against toxic metals such as lead and mercury, and slowing the aging process.
Chlorella is also used to increase “good” bacteria in the intestine in order to improve digestion; and to help treat ulcers, colitis, Crohn’s disease, and diverticulosis.
Some people also use it for the prevention of stress-related ulcers; treatment of constipation, bad breath, and hypertension; as an antioxidant; to reducecholesterol; to increase energy; to detoxify the body; and as a source of magnesium to promote mental health, relieve premenstrual syndrome (PMS), and reduce asthma attacks. It is also used for fibromyalgia.
Chlorella is applied to the skin for treating skin ulcers, rashes caused by radiation treatment, and a sexually transmitted disease called trichomoniasis.
How does it work?
A good source of protein, fats, carbohydrates, fiber, chlorophyll, vitamins, and minerals. The cell wall of chlorella must be broken down before people can digest it.