Chlorella
Chlorella | |
---|---|
Chlorella vulgaris | |
Scientific classification | |
(unranked): | Viridiplantae |
Division: | Chlorophyta |
Class: | Trebouxiophyceae |
Order: | Chlorellales |
Family: | Chlorellaceae |
Genus: | Chlorella M.Beijerinck, 1890 |
Species | |
Chlorella is a
The name Chlorella is taken from the
Chlorella has been considered as a source of food and energy because its
Taxonomy
Chlorella was first described by Martinus Beijerinck in 1890. Since then, over a hundred taxa have been described within the genus. However, biochemical and genomic data has revealed that many of these species were not closely related to each other, even being placed in a separate class Chlorophyceae. In other words, the "green ball" form of Chlorella appears to be a product of convergent evolution and not a natural taxon.[3] Identifying Chlorella-like algae based on morphological features alone is generally not possible.[4]
Some strains of "Chlorella" used for food are incorrectly identified, or correspond to genera that were classified out of true Chlorella. For example, Heterochlorella luteoviridis is typically known as Chlorella luteoviridis which is no longer considered a valid name.[5]
As a food source
When first harvested, Chlorella was suggested as an inexpensive protein supplement to the human diet. According to the American Cancer Society, "available scientific studies do not support its effectiveness for preventing or treating cancer or any other disease in humans".[6]
Under certain growing conditions, Chlorella yields oils that are high in polyunsaturated fats—Chlorella minutissima has yielded eicosapentaenoic acid at 39.9% of total lipids.[7]
History
Following global fears of an uncontrollable human population boom during the late 1940s and the early 1950s, Chlorella was seen as a new and promising primary food source and as a possible solution to the then-current world hunger crisis. Many people during this time thought hunger would be an overwhelming problem and saw Chlorella as a way to end this crisis by providing large amounts of high-quality food for a relatively low cost.[8]
Many institutions began to research the algae, including the
To cope with the upcoming postwar population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the Stanford Research Institute showed Chlorella (when growing in warm, sunny, shallow conditions) could convert 20% of solar energy into a plant that, when dried, contains 50% protein.[8] In addition, Chlorella contains fat and vitamins. The plant's photosynthetic efficiency allows it to yield more protein per unit area than any plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a 1000-acre (4-km2) Chlorella farm.[8] The pilot research performed at Stanford and elsewhere led to immense press from journalists and newspapers, yet did not lead to large-scale algae production. Chlorella seemed like a viable option because of the technological advances in agriculture at the time and the widespread acclaim it got from experts and scientists who studied it. Algae researchers had even hoped to add a neutralized Chlorella powder to conventional food products, as a way to fortify them with vitamins and minerals.[8]
When the preliminary laboratory results were published, the scientific community at first backed the possibilities of Chlorella.
Current status
Since the growing world food problem of the 1940s was solved by better crop efficiency and other advances in traditional agriculture, Chlorella has not seen the kind of public and scientific interest that it had in the 1940s. Chlorella has only a niche market for companies promoting it as a dietary supplement.[8]
Production difficulties
The experimental research was carried out in laboratories, rather than in the field, and scientists discovered that Chlorella would be much more difficult to produce than previously thought. To be practical, the algae grown would have to be placed either in
Although the production of Chlorella looked promising and involved creative technology, it has not to date been cultivated on the scale some had predicted. It has not been sold on the scale of Spirulina, soybean products, or whole grains. Costs have remained high, and Chlorella has for the most part been sold as a health food, for cosmetics, or as animal feed.[10] After a decade of experimentation, studies showed that following exposure to sunlight, Chlorella captured just 2.5% of the solar energy, not much better than conventional crops.[8] Chlorella, too, was found by scientists in the 1960s to be impossible for humans and other animals to digest in its natural state due to the tough cell walls encapsulating the nutrients, which presented further problems for its use in American food production.[8]
Use in carbon dioxide reduction and oxygen production
In 1965, the Russian
Dietary supplement
Chlorella is consumed as a dietary supplement. Manufacturers of Chlorella products falsely assert that it has purported health effects,[12] including an ability to treat cancer,[13] for which the American Cancer Society stated "available scientific studies do not support its effectiveness for preventing or treating cancer or any other disease in humans".[13] The United States Food and Drug Administration has issued warning letters to supplement companies for falsely advertising health benefits of consuming chlorella products, such as one company in October 2020.[14]
There is some support from animal studies of chlorella's ability to detoxify
Health concerns
A 2002 study showed that Chlorella cell walls contain
See also
- Calvin cycle
- List of ineffective cancer treatments
- Quorn (food product): made from mycoprotein
- Soyuz 28, a 1978 space mission which included experiments on Chlorella
- Spirulina (dietary supplement)
- Chlorellosis, a disease caused by the infection of Chlorella.
References
- ^ Scheffler, John (3 September 2007). "Underwater Habitats". Illumin. 9 (4).
- ^ Zelitch, I. (1971). Photosynthesis, Photorespiration and Plant Productivity. Academic Press. p. 275.
- PMID 25500553.
- .
- S2CID 254605212.
- ^ "Chlorella". American Cancer Society. 29 April 2011. Archived from the original on 5 September 2013. Retrieved 23 August 2013.
- PMID 2014989.
- ^ S2CID 109494408.
- ISBN 978-0-87279-611-9.
- ^ PMID 17196357.
- ^ "Russian CELSS Studies". Space Colonies. Permanent. Retrieved 3 November 2012.
- ^ Sun Chlorella, Going Green from the Inside Out – LA Sentinel
- ^ a b "Chlorella". American Cancer Society. 29 April 2011. Archived from the original on 5 September 2013. Retrieved 13 September 2013.
- ^ William A. Correll (20 October 2020). "FDA Warning Letter to ForYou Inc". Inspections, Compliance, Enforcement, and Criminal Investigations, US Food and Drug Administration. Retrieved 9 March 2021.
- PMID 6202479.
- ^ Sasik, Roman (19 January 2012). "Trojan horses of Chlorella 'superfood'". Robb Wolf.
- PMID 12414578.
- PMID 17203472.
- PMID 16563160.