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What Doctors Don't Tell You

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October 2019 (Vol. 4 Issue 8)

Chlorella: all-purpose algae?

About the author: 

Chlorella: all-purpose algae? image

Chlorella, a single-celled green algae from the Far East, is a popular food supple-ment with a host of purported benefits

Chlorella, a single-celled green algae from the Far East, is a popular food supple-ment with a host of purported benefits. The most common claim is that it can rid the body of toxic heavy metals, but it's also said to boost immunity, fix high blood pressure and even fight cancer. So, is there
any science behind this so-called wonder supplement?

Cancer claims

Although there are studies to suggest that Chlorella may be a powerful anticancer agent, most of them have been in animals or test-tubes. Still, the findings so far are promising.

In one study, Chlorella vulgaris (CV)-one species commonly used in supplements-was found to kill liver cancer cells in rats. The higher the dose, the stronger the effect, showing that Chlorella had a "definite chemo-preventive effect".

The researchers reported that the algae worked by inducing apoptosis, or programmed cell death, which removes damaged or 'bad cells' from the system.

"The results of the study could justify the role of CV in the treatment of thousands of liver cancer patients, thereby opening a new door for future research," the study concluded (J Zhejiang Univ Sci B, 2009; 10: 14-21).

These results have recently been replicated in a test-tube study of human liver cancer cells, demonstrating that this was not just a one-off finding (Clinics [Sao Paulo], 2010; 65: 1371-7).

In addition to liver cancer, Chlorella might also be useful for cancer of the colon. A study by the Korea Institute of Science and Technology found that extracts of two types of the algae-C. vulgaris and C. ellipsoidea-inhibited the growth of human cancer cells in the lab. Again, the higher the dose, the greater the effect.

The scientists attributed the effects to the "bioactive xanthophylls"-yellow pigments belonging to the carotenoid family-found in Chlorella that, they concluded, "might be useful functional ingredients in the prevention of human cancers" (J Agric Food Chem, 2008; 56: 10521-6).
Although these studies suggest a potential role for Chlorella in cancer treatment and/or prevention, the findings have yet to be replicated in clinical trials. This means that we just don't know if the results would be the same in people.

However, there is one human trial that looked at the effects of Chlorella supple-mentation in brain-cancer patients. In this study, C. pyrenoidosa (in the form of 20-g Sun Chlorella tablets and 150 mL of Wakasa Gold, a liquid Chlorella extract, both taken daily) was added to the diet of 21 glioma patients as an adjunct to what-ever other treatments they might have been receiving for their brain tumours. Although it did not significantly increase survival time, it did appear to boost their immune systems, increasing levels of natural-killer cells and lymphocytes.
"These variables were less adversely affected by chemotherapy and the immu-nosuppressive effects of medications and protein secretions of the tumours than would have been expected in these patients," the researchers said. However, they nevertheless highlighted the need for controlled clinical studies to confirm their findings (Phytother Res, 1990; 4: 220-31).

Other benefits?

A handful of other clinical trials suggest that Chlorella may be beneficial for a number of chronic conditions besides cancer. The researchers responsible for the brain cancer trial also tested the two C. pyrenoidosa-derived products on patients with fibromyalgia (a chronic pain condition), hypertension (high blood pressure) and ulcerative colitis (an inflammatory bowel disease)-all with encouraging results.

In the fibromyalgia study, which was a double-blind placebo-controlled trial, 37 patients were given either a placebo or Chlorella supplements (10 g as tablets and 100 mL as the liquid extract) daily for three months. After this time, the patients were switched to the other treatment group, and then treated for an additional three months. The results showed significant improvements in symptoms when participants used Chlorella compared with a placebo (Altern Ther Health Med, 2001; 7: 79-91).

In the hypertension trial, 24 people with mild-to-moderate hypertension took a placebo for four weeks, and then switched to the Chlorella supplements (again, 10 g/day as tablets and 100 mL/day as liquid extract). After two months of taking the algae, more than a third of patients (38 per cent) showed some improvement in their hypertension, and one-fourth had an excellent response, achieving their sitting diastolic blood pressure goal of less than 90 mmHg. Moreover, the researchers found a significant decrease in blood cholesterol levels (J Med Food, 2002; 5: 141-52).

The same dosages of Chlorella tablets and extract were trialled for a third time in nine ulcerative colitis patients for two months. In every single patient, the Disease Activity Index (DAI)-calculated from their symptoms and a physician's assessment-declined over the two months of algae supplementation. On average, the patients' DAIs fell from 7.2 to 2.8-a 61-per-cent drop that was highly significant. Scores for the emotional aspects of the disease were also signif-icantly improved. However, this was not a controlled study, so we don't know how much the placebo effect might have come into play (Altern Ther Health Med, 2001; 7: 79-91).

These studies are promising, but much more research is needed before it can be claimed that Chlorella is beneficial for these or any other health conditions. It should also be pointed out that the studies were funded by the Sun Chlorella Corporation, the company that makes the products used in the trials. Nevertheless, lead trial researcher Dr Randall Merchant, a professor at the Virginia Commonwealth University's Department of Anatomy and Neurobiology, maintains that the company does not influence his research or its outcomes, and that he rigorously follows the principles of experimental design and analysis (Altern Complement Ther, 2001; 7: 161-5).


Of all the health claims for Chlorella, the most popular one is that it can help rid the body of environmental toxins such as heavy metals-and there's convincing scientific evidence to support this.

The unique cell-wall structure of these algae contains compounds that bind to and remove heavy metals such as cad-mium, lead and mercury from the body, as well as accelerate the removal of dangerous chlorinated hydrocarbon-based insecticides (Townsend Lett, 2007; 287: 58-63).
In one of the earliest studies, feeding C. protothecoides to chlordecone-poison-ed rats was found to significantly speed up the detox process, decreasing the half-life of the carcinogenic insecticide from 40 to 19 days (Drug Chem Toxicol, 1984; 7: 57-71).

In another study, researchers in Japan fed rats highly toxic dioxins (industrial chemicals that we're all widely exposed to) as part of either a control diet or a 10-per-cent Chlorella diet, then measured the amount of dioxins excreted by the rats. Those fed the algae excreted significantly more dioxins than the controls, leading the researchers to conclude that Chlorella might prevent the gastrointestinal uptake of these chemicals while promoting the excretion of dioxins already absorbed in the tissues (J Nutr, 1999; 129: 1731-6).

As for heavy metals, studies in mice show that Chlorella can boost the removal of cadmium (Nutr Res Pract, 2009; 3: 15-22), lead (Toxicol Ind Health, 2009; 25: 551-6) and mercury (J Toxicol Sci, 2010; 35: 101-5).

As the results of these animal studies, however, do not necessarily apply to humans, once again, clinical trials are needed. But there is one published study-involving 35 pregnant women in Japan-which showed that those who took C. pyrenoidosa supplements had significantly lower dioxin levels in their breast milk compared with controls.

"These results suggest that Chlorella supplementation by the mother may reduce transfer of dioxins to the child through breast milk," the researchers reported (J Med Food, 2007; 10: 134-42).

The bottom line

In our increasingly toxic world, Chlorella is potentially a highly useful supplement, helping us to eliminate harmful contaminants from our bodies. However, the published evidence is still limited and more research is needed before definitive health claims can be made.

If you do wish to try Chlorella, be sure to choose a high-quality supplement (such as Sun Chorella, the brand used in the Virginia trials; see www.sunchlorella. com), as there have been concerns that the algae can be contaminated by heavy metals from the water in which it grows.
Chlorella itself appears to be non-toxic, although minor side-effects have been reported, including diarrhoea, stomach cramps and nausea. There's also the possibility of an allergic reaction, which can manifest as breathing difficulties, chest pain or hives. People taking blood-thinners such as warfarin are advised to avoid Chlorella, as the vitamin K in the algae has the opposite effect of warfarin.

Joanna Evans

Factfile: What's in Chlorella?

According to the website, 100 g of Sun Chlorella A (Chlorella pyrenoidosa tablets) will provide the following nutrients (see the website for a complete list of the ingredients).
u Chlorophyll 2700 mg
u Carotene 20,300 mcg
u Vitamin B1 1.82 mg
u Vitamin B2 4.52 mg
u Vitamin C 7 mg
u Vitamin D 479 mcg
u Vitamin E 5 mg
u Vitamin K1 1280 mcg
u Niacin 54.7 mg
u Calcium 340 mg
u Iron 120 mg
u Magnesium 330 mg
u Potassium 950 mg
u Phosphorus 1500 mg.


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