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When first harvested, ''Chlorella'' was suggested as a "dirt-cheap" protein supplement to the human diet. Advocates sometimes focus on other supposed health benefits of the algae, such as claims of weight control, cancer prevention, and immune system support.<ref name= "belasco"/>
When first harvested, ''Chlorella'' was suggested as a "dirt-cheap" protein supplement to the human diet. Advocates sometimes focus on other supposed health benefits of the algae, such as claims of weight control, cancer prevention, and immune system support.<ref name= "belasco"/>


Under certain growing conditions, ''Chlorella'' yields oils that are high in [[polyunsaturated fat]]s—''Chlorella minutissima'' has yielded [[Eicosapentaenoic acid|EPA]] at 39.9% of total lipids.<ref name=Yongmanitchai>{{cite journal | author=Yongmanitchai | journal= [[Appl Environ Microbiol]]| date = February 1991| volume=57|issue=2|pages= 419–425 | title=Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions | url= http://aem.asm.org/cgi/reprint/57/2/419 |accessdate=2007-10-23 | pmid=2014989 | last2=Ward | first2=OP | pmc=182726 }}</ref>
Under certain growing conditions, ''Chlorella'' yields oils that are high in [[polyunsaturated fat]]s—''Chlorella minutissima'' has yielded [[Eicosapentaenoic acid|EPA]] at 39.9% of total lipids.<ref name=Yongmanitchai>{{cite journal |pmid=2014989}}</ref>


One small (35 participant) study suggested ''Chlorella'' supplementation has a positive effect on the reduction of [[Dioxins and dioxin-like compounds|dioxin]] levels in [[breast milk]] and it may also have beneficial effects on nursing infants by increasing the [[IgA]] levels in breast milk.<ref>{{cite journal | author=Nakano, S., Takekoshi, H. Nakano, M. | journal= Journal of Medicinal Food | date = March 2007| volume=10 | issue=1 | pmid=17472477 | pages= 134–142 | title=Chlorella (Chlorella pyrenoidosa) supplementation decreases dioxin and increases immunoglobulin a concentrations in breast milk. | doi=10.1089/jmf.2006.023}}</ref>
One small (35 participant) study suggested ''Chlorella'' supplementation has a positive effect on the reduction of [[Dioxins and dioxin-like compounds|dioxin]] levels in [[breast milk]] and it may also have beneficial effects on nursing infants by increasing the [[IgA]] levels in breast milk.<ref>{{cite journal |doi=10.1089/jmf.2006.023}}</ref>


=== History ===
=== History ===


Following global fears of an uncontrollable 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.<ref name= "belasco">{{Cite journal
Following global fears of an uncontrollable 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.<ref name= "belasco">{{cite journal |first1=Warren |last1=Belasco |month=July |year=1997 |title=Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine |journal=Technology and Culture |volume=38 |issue=3 |pages=608-34 |jstor=3106856}}</ref>
| last= Belasco
| first= W.
| author-link=
| publication-date= July 1997
| title= Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine
| periodical=
| publication-place=
| place=
| publisher=
| volume= 38
| issue= 3
| pages= 608–634
}}.</ref>


Many institutions began to research the algae, including the [[Carnegie Institution of Washington|Carnegie Institution]], the [[Rockefeller Foundation]], the [[National Institutes of Health|NIH]], [[University of California, Berkeley|UC Berkeley]], the [[United States Atomic Energy Commission|Atomic Energy Commission]], and [[Stanford University]]. Following [[WWII]], many Europeans were starving and many [[Malthusianism|Malthusians]] attributed this not only to the war, but to the inability of the world to produce enough food to support the currently-increasing population. According to a 1946 [[FAO]] report, the world would need to produce 25 to 35 percent more food in 1960 than in 1939 to keep up with the increasing population, while health improvements would require a 90 to 100 percent increase.<ref name= "belasco"/> Because meat was costly and energy-intensive to produce, protein shortages were also an issue. Increasing cultivated area alone would go only so far in providing adequate nutrition to the population. The [[United States Department of Agriculture|USDA]] calculated that, to feed the U.S. population by 1975, it would have to add 200 million acres (800,000&nbsp;km²) of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested solely on new agricultural techniques and technologies. Because of these circumstances, an alternative solution was needed.
Many institutions began to research the algae, including the [[Carnegie Institution of Washington|Carnegie Institution]], the [[Rockefeller Foundation]], the [[National Institutes of Health|NIH]], [[University of California, Berkeley|UC Berkeley]], the [[United States Atomic Energy Commission|Atomic Energy Commission]], and [[Stanford University]]. Following [[WWII]], many Europeans were starving and many [[Malthusianism|Malthusians]] attributed this not only to the war, but to the inability of the world to produce enough food to support the currently-increasing population. According to a 1946 [[FAO]] report, the world would need to produce 25 to 35 percent more food in 1960 than in 1939 to keep up with the increasing population, while health improvements would require a 90 to 100 percent increase.<ref name= "belasco"/> Because meat was costly and energy-intensive to produce, protein shortages were also an issue. Increasing cultivated area alone would go only so far in providing adequate nutrition to the population. The [[United States Department of Agriculture|USDA]] calculated that, to feed the U.S. population by 1975, it would have to add 200 million acres (800,000&nbsp;km²) of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested solely on new agricultural techniques and technologies. Because of these circumstances, an alternative solution was needed.
Line 57: Line 44:
To cope with the upcoming post-war population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the [[SRI International|Stanford Research Institute]] showed ''Chlorella'' (when growing in warm, sunny, shallow conditions) could convert 20 percent of solar energy into a plant that, when dried, contains 50 percent protein.<ref name= "belasco"/> In addition, ''Chlorella'' contains fat and vitamins. The plant's photosynthetic efficiency allows it to yield more protein per unit area than any other plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a one-thousand-acre (4-square kilometer) ''Chlorella'' farm.<ref name= "belasco"/> 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.<ref name= "belasco"/>
To cope with the upcoming post-war population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the [[SRI International|Stanford Research Institute]] showed ''Chlorella'' (when growing in warm, sunny, shallow conditions) could convert 20 percent of solar energy into a plant that, when dried, contains 50 percent protein.<ref name= "belasco"/> In addition, ''Chlorella'' contains fat and vitamins. The plant's photosynthetic efficiency allows it to yield more protein per unit area than any other plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a one-thousand-acre (4-square kilometer) ''Chlorella'' farm.<ref name= "belasco"/> 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.<ref name= "belasco"/>


When the preliminary laboratory results were published, the reaction of scientific literature backed the possibilities of the supposed superfood. ''[[Science News Letter]]'' praised the optimistic results in an article entitled "Algae to Feed the Starving." John Burlew, the editor of the [[Carnegie Institution of Washington]] book ''Algal Culture-from Laboratory to Pilot Plant'', stated, "the algae culture may fill a very real need,"<ref name="Algal Culture">{{cite book | title=Algal Culture-from Laboratory to Pilot Plant | publisher=Carnegie Institution of Washington | author=Edited by John Burlew | year=1953 | pages=6 | isbn=0-87279-611-6}}</ref> which ''Science News Letter'' turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds." The cover of the magazine also featured [[Arthur D. Little]]'s Cambridge laboratory, which was a supposed future food factory. A few years later, the magazine published an article entitled "Tomorrow's Dinner", which stated, "There is no doubt in the mind of scientists that the farms of the future will actually be factories." ''[[Science Digest]]'' also reported, "common pond scum would soon become the world's most important agricultural crop." At least in the decades that followed, algae was not cultivated on nearly that scale, however.
When the preliminary laboratory results were published, the reaction of scientific literature backed the possibilities of the supposed superfood. ''[[Science News Letter]]'' praised the optimistic results in an article entitled "Algae to Feed the Starving." John Burlew, the editor of the [[Carnegie Institution of Washington]] book ''Algal Culture-from Laboratory to Pilot Plant'', stated, "the algae culture may fill a very real need,"<ref name="Algal Culture">{{cite book |title=Algal Culture-from Laboratory to Pilot Plant |publisher=Carnegie Institution of Washington |editor1-first=John |editor1-last=Burlew |year=1953 |page=6 |isbn=0-87279-611-6}}</ref> which ''Science News Letter'' turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds." The cover of the magazine also featured [[Arthur D. Little]]'s Cambridge laboratory, which was a supposed future food factory. A few years later, the magazine published an article entitled "Tomorrow's Dinner", which stated, "There is no doubt in the mind of scientists that the farms of the future will actually be factories." ''[[Science Digest]]'' also reported, "common pond scum would soon become the world's most important agricultural crop." At least in the decades that followed, algae was not cultivated on nearly that scale, however.


=== Current status ===
=== Current status ===
Line 66: Line 53:
In the end, scientists discovered that ''Chlorella'' would be much more difficult to produce than previously thought. The experimental research was carried out in laboratories, not in the field. In order to be practical, the entire batch of algae grown would have to be placed either in [[artificial light]] or in shade to produce at its maximum photosynthetic efficiency. Also, for the ''Chlorella'' to be as productive as the world would require, it would have to be grown in [[carbonated water]], which would have added millions to the production cost. A sophisticated process, and additional cost, was required to harvest the crop, and, for ''Chlorella'' to be a viable food source, its [[cellulose]] cell walls would have to be pulverized. The plant could reach its nutritional potential only in highly-modified artificial situations. Another problem was developing sufficiently palatable food products from ''Chlorella.''<ref name="becker" />
In the end, scientists discovered that ''Chlorella'' would be much more difficult to produce than previously thought. The experimental research was carried out in laboratories, not in the field. In order to be practical, the entire batch of algae grown would have to be placed either in [[artificial light]] or in shade to produce at its maximum photosynthetic efficiency. Also, for the ''Chlorella'' to be as productive as the world would require, it would have to be grown in [[carbonated water]], which would have added millions to the production cost. A sophisticated process, and additional cost, was required to harvest the crop, and, for ''Chlorella'' to be a viable food source, its [[cellulose]] cell walls would have to be pulverized. The plant could reach its nutritional potential only in highly-modified artificial situations. Another problem was developing sufficiently palatable food products from ''Chlorella.''<ref name="becker" />
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 (dietary supplement)|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]].<ref name="becker">{{Cite journal | doi = 10.1016/j.biotechadv.2006.11.002 | title = Micro-algae as a source of protein | year = 2007 | last1 = Becker | first1 = E | journal = [[Biotechnology Advances]] | volume = 25 | issue = 2 | pages = 207–210 | pmid = 17196357 | postscript = <!-- Bot inserted parameter. Either remove it or change its value to "." for the cite to end in a ".", as necessary. -->{{inconsistent citations}} }}</ref> After a decade of experimentation, studies showed that, following exposure to sunlight, ''Chlorella'' captured just 2.5 percent {{clarify|date=November 2011}}<!--2.5% of what?--> — not much better than conventional crops.<ref name= "belasco"/> ''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.<ref name= "belasco"/>
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 (dietary supplement)|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]].<ref name="becker">{{cite journal |doi=10.1016/j.biotechadv.2006.11.002}}</ref> After a decade of experimentation, studies showed that, following exposure to sunlight, ''Chlorella'' captured just 2.5 percent {{clarify|date=November 2011}}<!--2.5% of what?--> — not much better than conventional crops.<ref name= "belasco"/> ''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.<ref name= "belasco"/>


== Use in carbon dioxide reduction and oxygen production ==
== Use in carbon dioxide reduction and oxygen production ==


In 1965, the Russian [[CELSS]] experiment [[BIOS-3]] determined that 8 square meters of exposed chlorella could remove carbon dioxide and replace oxygen within the sealed environment for a single human. The chlorella was grown in vats underneath artificial light.<ref>Permanent Russian CELSS Studies, 6.9. [http://www.permanent.com/russian-celss.html retrieved:07/10/2012.]</ref>
In 1965, the Russian [[CELSS]] experiment [[BIOS-3]] determined that 8 square meters of exposed chlorella could remove carbon dioxide and replace oxygen within the sealed environment for a single human. The chlorella was grown in vats underneath artificial light.<ref>{{cite web |publisher=Permanent |title=Russian CELSS Studies |url=http://www.permanent.com/russian-celss.html |accessdate=3 November 2012 |work=Space Colonies}}</ref>


== Claims of health and healing effects ==
== Claims of health and healing effects ==


Because of its unique ability to bind with [[mercury (element)|mercury]], [[lead]], and [[cadmium]], the alga (chlorella vulgaris) has become increasing popular as a [[heavy metal (chemistry)|heavy metal]] "detoxifier". Studies indicate that chlorella (vulgaris etc.) demonstrates a superior ability to (safely) draw these toxic metals from the gut and intestinal tract (where they tend to accumulate).<ref>{{Cite pmid|18800895}}</ref><ref>Sorption of mercury, cadmium and lead by microalgae, Science Asia; 28 (2002) : 253-261. pdf:http://www.scienceasia.org/2002.28.n3/v28_253_261.pdf ; retrieved:19/01/2012.</ref><ref>Chlorella vulgaris administration prevents HgCl2-caused oxidative stress and cellular damage in the kidney; Journal of Applied Phycology, Volume 23, Number 1, 53-58. [http://www.springerlink.com/content/aj330507x7881704/ retrieved:10/01/2012.]</ref>
Because of its unique ability to bind with [[mercury (element)|mercury]], [[lead]], and [[cadmium]], the alga (chlorella vulgaris) has become increasing popular as a [[heavy metal (chemistry)|heavy metal]] "detoxifier". Studies indicate that chlorella (vulgaris etc.) demonstrates a superior ability to (safely) draw these toxic metals from the gut and intestinal tract (where they tend to accumulate).<ref>{{cite journal |pmid=18800895}}</ref><ref>{{cite journal |doi=10.2306/scienceasia1513-1874.2002.28.253}}</ref><ref>{{cite journal |doi=10.1007/s10811-010-9534-6}}</ref>
Like [[Aphanizomenon flos-aquae|blue-green algae]], clinical studies on ''Chlorella'' suggest effects including [[polychlorinated dibenzodioxins]] detoxification in humans <ref name="nakano">Nakano, S et al. “Maternal-fetal distribution and transfer of dioxins in pregnant women in Japan, and attempts to reduce maternal transfer with Chlorella (Chlorella pyrenoidosa) supplements...”'' Chemosphere'' 2005 Dec; 61(9): 1244–55.</ref> and animals,<ref name="takekoshi">Takekoshi, H et al. “Effect of Chlorella pyrenoidosa on fecal excretion and liver accumulation of polychlorinated dibenzo-p-dioxin in mice”. ''Chemosphere'' 2005 Apr; 59(2): 297b–304.</ref> healing from radiation exposure in animals <ref name="singh">Singh, SP et al. “Post-exposure radioprotection by Chlorella vulgaris (E-25) in mice”. ''Indian J Exp Biol.'' 1995 Aug; 33(8): 612–5.</ref> and the ability to reduce high blood pressure, lower serum [[cholesterol]] levels, accelerate [[wound healing]], and enhance immune functions in humans.<ref name="merchant">{{Cite PMID|11347287}}</ref>
Like [[Aphanizomenon flos-aquae|blue-green algae]], clinical studies on ''Chlorella'' suggest effects including [[polychlorinated dibenzodioxins]] detoxification in humans <ref name="nakano">{{cite journal |doi=10.1016/j.chemosphere.2005.03.080}}</ref> and animals,<ref name="takekoshi">{{cite journal |doi=10.1016/j.chemosphere.2004.11.026}}</ref> healing from radiation exposure in animals<ref name="singh">{{cite journal |pmid=8543329}}</ref> and the ability to reduce high blood pressure, lower serum [[cholesterol]] levels, accelerate [[wound healing]], and enhance immune functions in humans.<ref name="merchant">{{cite journal |pmid=11347287}}</ref>


''Chlorella'' has been found to have [[anti-tumor]] properties when fed to mice.<ref>{{Cite PMID|2229925}}</ref><ref>{{Cite PMID|3253484}}</ref><ref>{{Cite PMID|3845850}}</ref>
''Chlorella'' has been found to have [[anti-tumor]] properties when fed to mice.<ref>{{cite journal |pmid=2229925}}</ref><ref>{{cite journal |pmid=3253484}}</ref><ref>{{cite journal |pmid=3845850}}</ref>
Another study found enhanced vascular function in [[hypertensive]] rats given oral doses of chlorella.<ref>{{Cite PMID|17330510}}</ref> However, the use of ''Chlorella'' for healing effects has received criticism.<ref name="becker">E.W. Becker (1994). ''Microalgae: Biotechnology and Microbiotechnology''. [[Cambridge University Press]].</ref>
Another study found enhanced vascular function in [[hypertensive]] rats given oral doses of chlorella.<ref>{{cite journal |pmid=17330510}}</ref> However, the use of ''Chlorella'' for healing effects has received criticism.<ref name="becker">{{cite book |first=E. W. |last=Becker |year=1994 |title=Microalgae: Biotechnology and Microbiotechnology |publisher=[[Cambridge University Press]]}}{{pn}}</ref>


== Health concerns ==
== Health concerns ==
A 2002 study showed that Chlorella cell walls contain [[Lipopolysaccharides]], an [[endotoxin]] (also found in [[Gram-negative_bacteria]]) that affects the [[immune system]] and may cause [[inflammation]].<ref>http://robbwolf.com/2012/01/19/trojan-horses-of-chlorella-superfood/</ref><ref>http://www.ncbi.nlm.nih.gov/pubmed/12414578</ref><ref>http://www.ncbi.nlm.nih.gov/pubmed/19916503</ref><ref>http://www.ncbi.nlm.nih.gov/pubmed/17203472</ref>
A 2002 study showed that Chlorella cell walls contain [[Lipopolysaccharides]], an [[endotoxin]] (also found in [[Gram-negative_bacteria]]) that affects the [[immune system]] and may cause [[inflammation]].<ref>http://robbwolf.com/2012/01/19/trojan-horses-of-chlorella-superfood/{{full}}</ref><ref>{{cite journal |pmid=12414578}}</ref><ref>{{cite journal |pmid=19916503}}</ref><ref>{{cite journal |pmid=17203472}}</ref>


== Aquarium ==
== Aquarium ==

Revision as of 13:38, 3 November 2012

Chlorella
Chlorella regularis
Scientific classification
Domain:
Eukaryota
Kingdom:
Protista
Division:
Chlorophyta
Class:
Trebouxiophyceae
Order:
Chlorellales
Family:
Chlorellaceae
Genus:
Chlorella
Species

Chlorella minutissima
Chlorella pyrenoidosa
Chlorella variabilis
Chlorella vulgaris

Chlorella is a genus of single-cell green algae, belonging to the phylum Chlorophyta. It is spherical in shape, about 2 to 10 μm in diameter, and is without flagella. Chlorella contains the green photosynthetic pigments chlorophyll-a and -b in its chloroplast. Through photosynthesis, it multiplies rapidly, requiring only carbon dioxide, water, sunlight, and a small amount of minerals to reproduce.[1]

The name Chlorella is taken from the Greek chloros, meaning green, and the Latin diminutive suffix ella, meaning small. German biochemist and cell physiologist Otto Heinrich Warburg, awarded with the Nobel Prize in Physiology or Medicine in 1931 for his research on cell respiration, also studied photosynthesis in Chlorella. In 1961, Melvin Calvin of the University of California received the Nobel Prize in Chemistry for his research on the pathways of carbon dioxide assimilation in plants using Chlorella. In recent years, researchers have made less use of Chlorella as an experimental organism because it lacks a sexual cycle and, therefore, the research advantages of genetics are unavailable.[citation needed]

Many people believed Chlorella could serve as a potential source of food and energy because its photosynthetic efficiency can, in theory, reach 8%,[2] comparable with other highly efficient crops such as sugar cane.

Chlorella as a food source

It is an attractive potential food source because it is high in protein and other essential nutrients; when dried, it is about 45% protein, 20% fat, 20% carbohydrate, 5% fibre, and 10% minerals and vitamins. Mass-production methods are now being used to cultivate it in large artificial circular ponds. It is also abundant in calories, fat, and vitamins.[3]

When first harvested, Chlorella was suggested as a "dirt-cheap" protein supplement to the human diet. Advocates sometimes focus on other supposed health benefits of the algae, such as claims of weight control, cancer prevention, and immune system support.[3]

Under certain growing conditions, Chlorella yields oils that are high in polyunsaturated fats—Chlorella minutissima has yielded EPA at 39.9% of total lipids.[4]

One small (35 participant) study suggested Chlorella supplementation has a positive effect on the reduction of dioxin levels in breast milk and it may also have beneficial effects on nursing infants by increasing the IgA levels in breast milk.[5]

History

Following global fears of an uncontrollable 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.[3]

Many institutions began to research the algae, including the Carnegie Institution, the Rockefeller Foundation, the NIH, UC Berkeley, the Atomic Energy Commission, and Stanford University. Following WWII, many Europeans were starving and many Malthusians attributed this not only to the war, but to the inability of the world to produce enough food to support the currently-increasing population. According to a 1946 FAO report, the world would need to produce 25 to 35 percent more food in 1960 than in 1939 to keep up with the increasing population, while health improvements would require a 90 to 100 percent increase.[3] Because meat was costly and energy-intensive to produce, protein shortages were also an issue. Increasing cultivated area alone would go only so far in providing adequate nutrition to the population. The USDA calculated that, to feed the U.S. population by 1975, it would have to add 200 million acres (800,000 km²) of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested solely on new agricultural techniques and technologies. Because of these circumstances, an alternative solution was needed.

To cope with the upcoming post-war 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 percent of solar energy into a plant that, when dried, contains 50 percent protein.[3] In addition, Chlorella contains fat and vitamins. The plant's photosynthetic efficiency allows it to yield more protein per unit area than any other plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a one-thousand-acre (4-square kilometer) Chlorella farm.[3] 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.[3]

When the preliminary laboratory results were published, the reaction of scientific literature backed the possibilities of the supposed superfood. Science News Letter praised the optimistic results in an article entitled "Algae to Feed the Starving." John Burlew, the editor of the Carnegie Institution of Washington book Algal Culture-from Laboratory to Pilot Plant, stated, "the algae culture may fill a very real need,"[6] which Science News Letter turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds." The cover of the magazine also featured Arthur D. Little's Cambridge laboratory, which was a supposed future food factory. A few years later, the magazine published an article entitled "Tomorrow's Dinner", which stated, "There is no doubt in the mind of scientists that the farms of the future will actually be factories." Science Digest also reported, "common pond scum would soon become the world's most important agricultural crop." At least in the decades that followed, algae was not cultivated on nearly that scale, however.

Current status

Since the growing world food problem of the 1940s was solved by better crop efficiency and not from a "super food," Chlorella has not seen the kind of public and scientific interest that it had in the 1940s. Chlorella can still be found today from companies promoting its "super-food" effects.[3]

Production difficulties

In the end, scientists discovered that Chlorella would be much more difficult to produce than previously thought. The experimental research was carried out in laboratories, not in the field. In order to be practical, the entire batch of algae grown would have to be placed either in artificial light or in shade to produce at its maximum photosynthetic efficiency. Also, for the Chlorella to be as productive as the world would require, it would have to be grown in carbonated water, which would have added millions to the production cost. A sophisticated process, and additional cost, was required to harvest the crop, and, for Chlorella to be a viable food source, its cellulose cell walls would have to be pulverized. The plant could reach its nutritional potential only in highly-modified artificial situations. Another problem was developing sufficiently palatable food products from Chlorella.[7]

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.[7] After a decade of experimentation, studies showed that, following exposure to sunlight, Chlorella captured just 2.5 percent [clarification needed] — not much better than conventional crops.[3] 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.[3]

Use in carbon dioxide reduction and oxygen production

In 1965, the Russian CELSS experiment BIOS-3 determined that 8 square meters of exposed chlorella could remove carbon dioxide and replace oxygen within the sealed environment for a single human. The chlorella was grown in vats underneath artificial light.[8]

Claims of health and healing effects

Because of its unique ability to bind with mercury, lead, and cadmium, the alga (chlorella vulgaris) has become increasing popular as a heavy metal "detoxifier". Studies indicate that chlorella (vulgaris etc.) demonstrates a superior ability to (safely) draw these toxic metals from the gut and intestinal tract (where they tend to accumulate).[9][10][11] Like blue-green algae, clinical studies on Chlorella suggest effects including polychlorinated dibenzodioxins detoxification in humans [12] and animals,[13] healing from radiation exposure in animals[14] and the ability to reduce high blood pressure, lower serum cholesterol levels, accelerate wound healing, and enhance immune functions in humans.[15]

Chlorella has been found to have anti-tumor properties when fed to mice.[16][17][18] Another study found enhanced vascular function in hypertensive rats given oral doses of chlorella.[19] However, the use of Chlorella for healing effects has received criticism.[7]

Health concerns

A 2002 study showed that Chlorella cell walls contain Lipopolysaccharides, an endotoxin (also found in Gram-negative_bacteria) that affects the immune system and may cause inflammation.[20][21][22][23]

Aquarium

Chlorella can create green and opaque water problems in aquaria. Chlorella can grow due to high nitrate and phosphate levels or direct sunlight. Decreasing phosphate and nitrate by partial water change and moving the aquarium to shade can help alleviate the problem.

See also

Wikimedia Commons has media related to Chlorella.

References

  1. ^ http://illumin.usc.edu/163/underwater-habitats/
  2. ^ I. Zelitch, Photosynthesis, Photorespiration and Plant Productivity, Academic Press, 1971, p.275.
  3. ^ a b c d e f g h i j Belasco, Warren (1997). "Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine". Technology and Culture. 38 (3): 608–34. JSTOR 3106856. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ . PMID 2014989. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  5. ^ . doi:10.1089/jmf.2006.023. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  6. ^ Burlew, John, ed. (1953). Algal Culture-from Laboratory to Pilot Plant. Carnegie Institution of Washington. p. 6. ISBN 0-87279-611-6.
  7. ^ a b c . doi:10.1016/j.biotechadv.2006.11.002. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help) Cite error: The named reference "becker" was defined multiple times with different content (see the help page).
  8. ^ "Russian CELSS Studies". Space Colonies. Permanent. Retrieved 3 November 2012.
  9. ^ . PMID 18800895. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  10. ^ . doi:10.2306/scienceasia1513-1874.2002.28.253. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  11. ^ . doi:10.1007/s10811-010-9534-6. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  12. ^ . doi:10.1016/j.chemosphere.2005.03.080. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  13. ^ . doi:10.1016/j.chemosphere.2004.11.026. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  14. ^ . PMID 8543329. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  15. ^ . PMID 11347287. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  16. ^ . PMID 2229925. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  17. ^ . PMID 3253484. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  18. ^ . PMID 3845850. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  19. ^ . PMID 17330510. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  20. ^ http://robbwolf.com/2012/01/19/trojan-horses-of-chlorella-superfood/[full citation needed]
  21. ^ . PMID 12414578. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  22. ^ . PMID 19916503. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  23. ^ . PMID 17203472. {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)

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