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What You Need to Know About Chlorella


Updated March 01, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Chlorella is a type of algae said to offer a range of health benefits. Available in supplement form, chlorella contains a number of antioxidants (including vitamin C and B-complex vitamins). Proponents claim that chlorella can help promote detox and, in turn, protect against cancer. Other purported benefits of chlorella include the treatment of high blood pressure, high cholesterol, ulcerative colitis, diverticulosis, Crohn's disease, pancreatitis, and liver problems.

The Science Behind Chlorella's Health Benefits

Despite abundant marketing claims for chlorella's health benefits, there is a lack scientific support for chlorella's effectiveness in treatment or prevention of any health problem. Although some animal studies and test-tube research suggests that chlorella may offer some cancer-fighting benefits, these findings have yet to be explored in clinical trials.

The available clinical trials on chlorella's health benefits include a 2003 study, which was designed to test chlorella's effects on the immune system. For the study, researchers assigned 124 healthy adults (ages 50 and older) to take either a chlorella supplement (at a dose of 200 or 400 mg) or a placebo supplement once daily for 28 days. On day 21 of the experiment, participants received a flu vaccine. Study results showed that chlorella failed to increase the antibody response to the vaccine (except among participants ages 50 to 55).

In a previous report, published in 2001, researchers studied the effects of chlorella supplements on 55 fibromyalgia patients, 33 people with high blood pressure, and nine people ulcerative colitis. For two or three months, the study participants took 10 g of chlorella in tablet form and 100 mL of chlorella extract in liquid form each day. In analyzing their findings, researchers determined that chlorella supplementation may help decrease blood pressure, lower cholesterol levels, promote wound healing, and enhance immune function.

Should You Take Chlorella for Health Purposes?

Due to the limited science behind chlorella's health effects, chlorella supplements cannot be recommended for any health condition. While chlorella appears to be safe, little is known about the adverse effects possibly associated with long-term use of chlorella supplements. If you're considering the use of chlorella supplements, make sure to consult your physician to weigh the potential benefits and risks.


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Halperin SA, Smith B, Nolan C, Shay J, Kralovec J. "Safety and immunoenhancing effect of a Chlorella-derived dietary supplement in healthy adults undergoing influenza vaccination: randomized, double-blind, placebo-controlled trial." CMAJ. 2003 Jul 22;169(2):111-7.

Merchant RE, Andre CA. "A review of recent clinical trials of the nutritional supplement Chlorella pyrenoidosa in the treatment of fibromyalgia, hypertension, and ulcerative colitis." Altern Ther Health Med. 2001 May-Jun;7(3):79-91.

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