Does Taking Chlorella Make You Feel Tired?

In recent years, natural supplements have gained increasing attention for their reported benefits in improving mental and physical health. Chlorella, a single-celled algae, has been widely used throughout Asia and is often recommended by naturopathic doctors and other alternative health practitioners to treat a number of conditions. While some research suggests that chlorella may help to alleviate certain chronic fatigue conditions, other research indicates that chlorella may actually induce fatigue. Consult your doctor if you are thinking about taking a chlorella supplement.

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About Chlorella

Chlorella is a freshwater, single-celled algae that contains a number of beneficial nutrients, including antioxidants such as vitamin C, vitamin E and carotenoids, B vitamins and alpha lipoic-acid, according to naturopath Linda Page in her book "Healthy Healing: A Guide to Self-Healing for Everyone." Chlorella is sold as a dietary supplement in powder, capsule, tablet and liquid form. The antioxidant benefits of chlorella have led proponents to claim it can help prevent cancer, enhance the immune system and fight infections. However, as of the date of publication, no scientific evidence supports these benefits. However, some research has shown that chlorella may help alleviate certain symptoms of chronic fatigue disorders like fibromyalgia. Interestingly, however, low doses of chlorella have also been reported to increase feelings of fatigue.

Chlorella and Fatigue

Studies on chlorella's benefits for reducing fatigue have been somewhat limited. A study published in 2001 in the "Journal of Musculoskeletal Pain" reports that patients with fibromyalgia, a complex condition whose symptoms include chronic pain and fatigue, experienced a decrease in symptoms, including fatigue and quality of sleep, when treated with chlorella in liquid or tablet form. Another study, published in 2006 in the "Annals of Nutrition and Metabolism," evaluated effects of a chlorella extract on laboratory mice exposed to a forced swim test and on fatigue-related parameters in their blood. The results found that the mice treated with chlorella had improved stamina, and that chlorella may also help to improve immune functioning. However, further studies are needed to fully determine the benefits of chlorella on fatigue in humans.

Adverse Effects

As of January 2014, only one study has shown fatigue as an adverse side effect of using chlorella supplementation. This study, published in the July 22, 2003 issue of the "Canadian Medical Association Journal," evaluated the effects of oral chlorella supplementation for its possible immune system enhancing benefits in healthy adults who received an influenza vaccination. Study participants received a placebo, a 200 mg or a 400 milligram daily dose of chlorella for 28 days. Fatigue was reported more frequently as an adverse side effect by patients who received the 200 milligram dosage than by those who received either the placebo or the 400 milligram dosage.


The American Cancer Society states that chlorella is reported to be safe in individuals who are not allergic; however, no studies have been conducted to determine the possibility of side effects or the potential effects of long-term use. As with any dietary supplement, inform your doctor if you plan to use chlorella. Never use dietary supplements as a replacement for conventional medical care.