Spirulina is the dried biomass of cyanobacteria (blue-green algae) that can be consumed by humans and animals. The three species are Arthrospira platensis , A. fusiformis, and A. maxima.
Cultivated worldwide, Arthrospira is used as a dietary supplement or whole food. [1] It is also used as a feed supplement in the aquaculture, aquarium, and poultry industries. [2]
The species A. maxima and A. platensis were once classified in the genus Spirulina. The common name, spirulina, refers to the dried biomass of A. platensis, [3] which belongs to photosynthetic bacteria that cover the groups Cyanobacteria and Prochlorophyta. Scientifically, a distinction exists between spirulina and the genus Arthrospira. Species of Arthrospira have been isolated from alkaline brackish and saline waters in tropical and subtropical regions. Among the various species included in the genus Arthrospira, A. platensis is the most widely distributed and is mainly found in Africa, but also in Asia. A. maxima is believed to be found in California and Mexico. [4] The term spirulina remains in use for historical reasons. [2]
Arthrospira species are free-floating, filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-handed helix. They occur naturally in tropical and subtropical lakes with high pH and high concentrations of carbonate and bicarbonate. [5] A. platensis occurs in Africa, Asia, and South America, whereas A. maxima is confined to Central America. [2] Most cultivated spirulina is produced in open-channel raceway ponds, with paddle wheels used to agitate the water. [5]
Spirulina thrives at a pH around 8.5 and above and a temperature around 30 °C (86 °F). They are autotrophic, meaning that they are able to make their own food, and do not need a living energy or organic carbon source. A nutrient feed for growing it [6] is:
Nutritional value per 100 g (3.5 oz) | |||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Energy | 1,213 kJ (290 kcal) | ||||||||||||||||||||||||||||||||||||||||||||||||||||
23.9 g | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Sugars | 3.1 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Dietary fiber | 3.6 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
7.72 g | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Saturated | 2.65 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Monounsaturated | 0.675 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Polyunsaturated | 2.08 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
57.47 g | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Tryptophan | 0.929 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Threonine | 2.97 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Isoleucine | 3.209 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Leucine | 4.947 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Lysine | 3.025 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Methionine | 1.149 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Cystine | 0.662 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Phenylalanine | 2.777 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Tyrosine | 2.584 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Valine | 3.512 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Arginine | 4.147 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Histidine | 1.085 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Alanine | 4.515 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Aspartic acid | 5.793 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Glutamic acid | 8.386 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Glycine | 3.099 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Proline | 2.382 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Serine | 2.998 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||
Other constituents | Quantity | ||||||||||||||||||||||||||||||||||||||||||||||||||||
Water | 4.68 g | ||||||||||||||||||||||||||||||||||||||||||||||||||||
†Percentages estimated using US recommendations for adults, [7] except for potassium, which is estimated based on expert recommendation from the National Academies. [8] |
Spirulina was a food source for the Aztecs and other Mesoamericans until the 16th century; the harvest from Lake Texcoco in Mexico and subsequent sale as cakes were described by one of Cortés's soldiers. [9] [10] The Aztecs called it tecuitlatl. [5]
Spirulina was found in abundance at Lake Texcoco by French researchers in the 1960s, but no reference to its use by the Aztecs as a daily food source was made after the 16th century, probably because of the draining of the surrounding lakes for agriculture and urban development. [5] The topic of tecuitlatl, which was discovered in 1520, was not mentioned again until 1940, when the Belgian phycologist Pierre Dangeard mentioned a cake called dihe consumed by the Kanembu tribe, who harvest it from Lake Chad in the African nation of Chad. Dangeard studied the dihe samples and found it to be a dried puree of the spring form of the blue-green algae from the lake. The dihe is used to make broths for meals, and also sold in markets. The spirulina is harvested from small lakes and ponds around Lake Chad. [11]
During 1964 and 1965, the botanist Jean Leonard confirmed that dihe is made up of spirulina, and later studied a bloom of algae in a sodium hydroxide production facility. As a result, the first systematic and detailed study of the growth requirements and physiology of spirulina was performed as a basis for establishing large-scale production in the 1970s. [2] [4]
Spirulina is being investigated to address food security and malnutrition, and as dietary support in long-term space flight or Mars missions. [12] [13] Its advantage for food security is that it needs less land and water than livestock to produce protein and energy. [12]
Dried spirulina contains 5% water, 24% carbohydrates, 8% fat, and about 60% (51–71%) protein. [14] [15]
An amount of 100g of spirulina in supplement form as a dried powder supplies 290 kilocalories (1,200 kJ) and is a rich source (20% or more of the Daily Value, DV) of numerous essential nutrients, particularly protein, B vitamins (thiamin, riboflavin, and niacin, providing 207%, 306%, and 85% DV, respectively), and dietary minerals, such as iron (219% DV) and manganese (90% DV). The lipid content of spirulina is 8% by weight providing the fatty acids, gamma-linolenic acid, [16] [17] linoleic acid, stearidonic acid, [18] eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid. [19] In contrast to those 2003 estimates (of DHA and EPA each at 2 to 3% of total fatty acids), 2015 research indicated that spirulina products "contained no detectable omega-3 fatty acids" (less than 0.1%, including DHA and EPA). [20]
Spirulina contains no vitamin B12 naturally, and spirulina supplements are not considered a reliable source of vitamin B12, as they contain predominantly pseudovitamin B12 (Coα-[α-(7-adenyl)]-Coβ-cyanocobamide), [21] which is biologically inactive in humans. [22] [23] In a 2009 position paper on vegetarian diets, the American Dietetic Association stated that spirulina is not a reliable source of active vitamin B12. [23] The medical literature similarly advises that spirulina is unsuitable as a source of B12. [22] [24]
Various studies on spirulina as an alternative feed for animal and aquaculture have been done. [4] Spirulina can be fed up to 10% for poultry [25] and less than 4% for quail. [26] An increase in spirulina content up to 40 g/kg (0.64 oz/lb) for 16 days in 21-day-old broiler male chicks resulted in yellow and red coloration of flesh, possibly due to the accumulation of the yellow pigment zeaxanthin. [27] Pigs [28] and rabbits [29] can receive up to 10% of the feed and increase in the spirulina content in cattle resulted in increase in milk yield and weight. [30] Spirulina has been established [4] as an alternative feedstock and immune booster for bigmouth buffalo, [30] milk fish, [31] cultured striped jack, [32] carp, [33] [34] red sea bream, [35] tilapia, [36] catfish, [37] yellow tail, [38] zebrafish, [39] shrimp, [40] [41] and abalone, [42] and up to 2% spirulina per day in aquaculture feed can be safely recommended. [4]
According to the U.S. National Institutes of Health, scientific evidence is insufficient to recommend spirulina supplementation for any human condition, and more research is needed to clarify whether consumption yields any benefits. [1] Administration of spirulina has been investigated as a way to control glucose in people with diabetes, but the European Food Safety Authority rejected those claims in 2013. [43] Spirulina has been studied as a potential nutritional supplement for adults and children affected by HIV, but there was no conclusive effect on risk of death, body weight, or immune response. [44] [45]
Spirulina may have adverse interactions when taken with prescription drugs, particularly those affecting the immune system and blood clotting. [1]
A number of cyanobacteria, of which spirulina is one, produce toxins such as microcystins. [46] Some spirulina supplements have been found to be contaminated with microcystins, albeit at levels below the limit set by the Oregon Health Department. [47] Microcystins can cause gastrointestinal upset, such as diarrhea, flatulence, headache, muscle pain, facial flushing, and sweating. [1] [46] Chronic exposure may lead to liver damage. [1] The effects of chronic exposure to even low levels of microcystins are a concern due to the risk of toxicity to several organ systems. [1] [47]
These toxic compounds are not produced by spirulina itself, [48] but can occur if spirulina batches are contaminated with other, toxin-producing, blue-green algae. Because the U.S. considers spirulina a dietary supplement, its government does not regulate its production and enforces no safety standards for its production or purity. [47] The U.S. National Institutes of Health describes spirulina supplements as "possibly safe", provided they are free of microcystin contamination, but "likely unsafe" (especially for children) if contaminated. [1] Given the lack of regulatory standards in the U.S., some public-health researchers have raised the concern that consumers cannot be certain that spirulina and other blue-green algae supplements are free of contamination. [47] In 1999, Health Canada found that one sample of spirulina was microcystin-free. ("...0/10 samples of Spirulina contained microcystins.") [49]
Heavy-metal contamination of spirulina supplements has also raised concern. The Chinese State Food and Drug Administration reported that lead, mercury, and arsenic contamination was widespread in spirulina supplements marketed in China. [50] One study reported the presence of lead up to 5.1 ppm in a sample from a commercial supplement. [4] Spirulina doses of 10 to 19 grams per day over several months have been used safely. [1]
Like all protein-rich foods, spirulina contains the essential amino acid phenylalanine (2.6–4.1 g/100 g), [5] which should be avoided by people who have phenylketonuria, a rare genetic disorder that prevents the body from metabolizing phenylalanine, which then builds up in the brain, causing damage. [51]
Microcystins have various potential toxicity, especially to children and pregnant women, [52] including liver damage, shock, and death. [1]
In 2024, a literature review on the allergic properties of spirulina was published. It was noted that to date (by July 2023), there have been 5 cases of allergy to spirulina, with 4 out of 5 cases resulting in anaphylaxis according to the classification from the World Allergy Organization's Anaphylaxis Guidance of 2020. Based on their research findings, instances of spirulina allergy are infrequently reported or identified., potentially due to spirulina's ability to inhibit mast cell degranulation, a critical component of allergic reactions. [53]
Omega−3 fatty acids, also called omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.
Vitamins are organic molecules that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in sufficient quantities for survival, and therefore must be obtained through the diet. For example, vitamin C can be synthesized by some species but not by others; it is not considered a vitamin in the first instance but is in the second. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, there are eight vitamers of vitamin E: four tocopherols and four tocotrienols.
Taurine, or 2-aminoethanesulfonic acid, is a non-proteinogenic naturally occurred amino sulfonic acid that is widely distributed in animal tissues. It is a major constituent of bile and can be found in the large intestine, and accounts for up to 0.1% of total human body weight.
Vitamin deficiency is the condition of a long-term lack of a vitamin. When caused by not enough vitamin intake it is classified as a primary deficiency, whereas when due to an underlying disorder such as malabsorption it is called a secondary deficiency. An underlying disorder can have 2 main causes:
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. They are a chemically diverse class of compounds.
Chlorella is a genus of about thirteen species of single-celled green algae of the division Chlorophyta. The cells are spherical in shape, about 2 to 10 μm in diameter, and are without flagella. Their chloroplasts contain the green photosynthetic pigments chlorophyll-a and -b. In ideal conditions cells of Chlorella multiply rapidly, requiring only carbon dioxide, water, sunlight, and a small amount of minerals to reproduce.
Vegetarian nutrition is the set of health-related challenges and advantages of vegetarian diets.
Cat food is food specifically formulated and designed for consumption by cats. As obligate carnivores, cats have specific requirements for their dietary nutrients, namely nutrients found only in meat or synthesised, such as taurine and Vitamin A. Certain nutrients, including many vitamins and amino acids, are degraded by the temperatures, pressures and chemical treatments used during manufacture, and hence must be added after manufacture to avoid nutritional deficiency. Cat food is typically sold as dry kibble, or as wet food in cans and pouches.
Phycocyanin is a pigment-protein complex from the light-harvesting phycobiliprotein family, along with allophycocyanin and phycoerythrin. It is an accessory pigment to chlorophyll. All phycobiliproteins are water-soluble, so they cannot exist within the membrane like carotenoids can. Instead, phycobiliproteins aggregate to form clusters that adhere to the membrane called phycobilisomes. Phycocyanin is a characteristic light blue color, absorbing orange and red light, particularly 620 nm, and emits fluorescence at about 650 nm. Allophycocyanin absorbs and emits at longer wavelengths than phycocyanin C or phycocyanin R. Phycocyanins are found in cyanobacteria. Phycobiliproteins have fluorescent properties that are used in immunoassay kits. Phycocyanin is from the Greek phyco meaning “algae” and cyanin is from the English word “cyan", which conventionally means a shade of blue-green and is derived from the Greek “kyanos" which means a somewhat different color: "dark blue". The product phycocyanin, produced by Aphanizomenon flos-aquae and Spirulina, is for example used in the food and beverage industry as the natural coloring agent 'Lina Blue' or 'EXBERRY Shade Blue' and is found in sweets and ice cream. In addition, fluorescence detection of phycocyanin pigments in water samples is a useful method to monitor cyanobacteria biomass.
Algaculture is a form of aquaculture involving the farming of species of algae.
Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria of the genus Aphanizomenon found around the world, including the Baltic Sea and the Great Lakes.
Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physicochemical properties of a biofilm. EPS in the matrix of biofilms provides compositional support and protection of microbial communities from the harsh environments. Components of EPS can be of different classes of polysaccharides, lipids, nucleic acids, proteins, lipopolysaccharides, and minerals.
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it.
Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes. They typically contain high amounts of fiber. They may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. Seaweeds are also harvested or cultivated for the extraction of polysaccharides such as alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance, especially in food production as food additives. The food industry exploits the gelling, water-retention, emulsifying and other physical properties of these hydrocolloids.
Arthrospira is a genus of free-floating filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-hand helix. A dietary supplement is made from A. platensis and A. maxima, known as spirulina. The A. maxima and A. platensis species were once classified in the genus Spirulina. Although the introduction of the two separate genera Arthrospira and Spirulina is now generally accepted, there has been much dispute in the past and the resulting taxonomical confusion is tremendous.
Vegan nutrition refers to the nutritional and human health aspects of vegan diets. A well-planned vegan diet is suitable to meet all recommendations for nutrients in every stage of human life. Vegan diets tend to be higher in dietary fiber, magnesium, folic acid, vitamin C, vitamin E, and phytochemicals; and lower in calories, saturated fat, iron, cholesterol, long-chain omega-3 fatty acids, vitamin D, calcium, zinc, and vitamin B12.
Microalgae or microscopic algae grow in either marine or freshwater systems. They are primary producers in the oceans that convert water and carbon dioxide to biomass and oxygen in the presence of sunlight.
Arthrospira platensis is a filamentous, gram-negative cyanobacterium. This bacterium is non-nitrogen-fixing photoautotroph. It has been isolated in Chenghai Lake, China, soda lakes of East Africa, and subtropical, alkaline lakes.
Protein quality is the digestibility and quantity of essential amino acids for providing the proteins in correct ratios for human consumption. There are various methods that rank the quality of different types of protein, some of which are outdated and no longer in use, or not considered as useful as they once were thought to be. The Protein Digestibility Corrected Amino Acid Score (PDCAAS), which was recommended by the Food and Agriculture Organization of the United Nations (FAO), became the industry standard in 1993. FAO has recently recommended the newer Digestible Indispensable Amino Acid Score (DIAAS) to supersede PDCAAS.
As in the human practice of veganism, vegan dog foods are those formulated with the exclusion of ingredients that contain or were processed with any part of an animal, or any animal byproduct. Vegan dog food may incorporate the use of fruits, vegetables, cereals, legumes including soya, nuts, vegetable oils, as well as any other non-animal based foods.
Most of the edible blue-green algae (cyanobacteria) used for human supplements predominantly contain pseudovitamin B(12), which is inactive in humans. The edible cyanobacteria are not suitable for use as vitamin B(12) sources, especially in vegans.
The results presented here strongly suggest that spirulina tablet algal health food is not suitable for use as a B12 source, especially in vegetarians.
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