Authors: Radha Gupta1, Reshu Tiwari2 and Sushma Tiwari1
Spirulina is a cyanobacterium, (Oscillatoraceae family) which acquired the ability for photosynthesis before any other organism and is considered to be the ancestor from which the higher plants evolved [Desai et al., 2004]. Spirulina refers to various species of blue-green algae found naturally in lakes and grown commercially. Arthrospira platensis earlier known as ‘Spirulina’ platensis is a ubiquitous spiral-shaped blue-green unicellular microalgae which grows in fresh water, in salt water, as well as in brackish bodies of water. It is so named because of the fact that the filaments are spiral. It grows best in a highly alkaline environment of pH 10-12. Such conditions currently exist in certain lakes in Sub-Saharan Africa and formerly in Mexico and Central America. Spirulina has been used as a food source for centuries. In Africa, Spirulina has served as the sole source of nutrition in certain communities in times of famine, and the entire native populations have existed eating only Spirulina for over a month at a time [Capelli et al 2010]. Spirulina is a suitable matrix for biotechnological incorporation of new food trace element preparation because it contain significant amounts of valuable proteins, indispensable amino acids, vitamins, beta-carotene, mineral substances, essential fatty acids, polysaccharides, glycolipids and sulpholipids etc. (Gupta et al., 2008). Spirulina also contains high level of various vitamins B, and minerals including calcium, iron, magnesium, manganese, potassium and zinc (Gireesh et al., 2004). It is a good source of polyunsaturated fatty acid gamma linolenic acid (GLA) (Gupta et al., 2008). They are accepted as functional food, which are defined as products derived from natural sources, whose consumption is likely to benefit human health and enhance performance. The addition of Spirulina to the diet can give a wide range of vital nutrients (Belay et al., 1997). 10 grams of Spirulina contains over 100mg of GLA. Spirulina was originally harvested from lakes in parts of Africa and Mexico, dried and used as a food but it gained prominence more recently after it was used as a dietary supplement for astronauts on space missions. Spirulina is one of the natural sources containing the highest amount of protein five times that of meat. NASA has stated that the nutritional value of 1000 kg of fruits and vegetables equals one kg of spirulina [Ravi et al 2002]. Various spirulina species are Spirulina maxima; Spirulina platensis, Spirulina pacifica (also known as Arthrospira platensis, Arthrospira maxima). Arthrospira platensis is the predominant species and commercially cultivated worldwide though Arthrospira maxima is produced in the South and Central American regions [Thomas 2010].
It contains ten times more protein than soya bean and three times to that of beef protein. It provides full compliment of nine essential amino acids. Dried Spirulina powder contains 65 to 70% protein. Spirulina is known to contain high percentage of glycolipids and sulpholipids. It contains 5-8% lipid, from which 40% are glycolipids and 2-5% are sulpholipids. Sulpholipid is of great therapeutic value. Spirulina contains high amount of bioavailable vitamin B 12 and this is particularly important for vegetarians who often find it hard to get this nutrient in their diet. The Vitamin E levels of dried Spirulina are also high (Thomas et al 2010).
Pigment content including chlorophyll and beta-carotene is also high. These pigments are called phycobilins, include phycocyanin and allophycocyanin. Phycobilins are similar in structure to bile pigments such as bilirubin. In Spirulina cell, phycobilins are attached to proteins; the phycobilin-protein complex is called phycobiliprotein (Thomas et al 2010). Studies have shown that the nutrients of Spirulina are readily absorbed by the body and help to bring nutrient status up to normal level. This is spatially true for minerals such as zinc and iron and vitamins. It is also beneficial for malnourished children (Ciferri, 1983).
Spirulina has been demonstrated to be an effective dietary source of vitamin A. An investigation in India on preschool children with vitamin A deficiency demonstrated that the bioavailability of carotenes from Spirulina was comparable to that from other sources such as carrots and green leafy vegetables thereby suggesting the potential use of Spirulina as a dietary source of vitamin. Spirulina has a positive impact on weight and other parameters like arm circumference, height, albumin, prealbumin, protein and haemoglobin improved after spirulina supplementation (Khan et al, 2005). Improvement in nutritional status of malnourished HIV-infected patients has also been shown by supplementing the diet with Spirulina. Moreover Spirulina can be safely administered to children without any risk and is considered a very suitable food (United Nations World Health Organization, Geneva, Switzerland June 8th, 1993).
Table 1: General Composition of Spirulina [ Thomas, 2010]
| S. No. | Composition | Percentage |
| 1 | Protein | 60 % - 69 % |
| 2 | Carbohydrates | 16 % - 20 % |
| 3 | Lipids | 5% - 7 % |
| 4 | Minerals | 6 % - 9% |
| 5 | Moisture | 2.5% - 6.0% |
| S. No. | Composition | Percentage |
| 1 | Total Carotenoids | 400 – 650 |
| 2 | Beta Carotene | 150 – 250 |
| 3 | Xanthophylls | 250 – 470 |
| 4 | Zeaxanthin | 125 – 200 |
| 5 | Chlorophyll | 1300 – 1700 |
| 6 | Phycocyanin | 15000 –19000 |
| S. No. | Composition | Percentage |
| 1 | Vitamin B1 (Thiamine) | 0.1.5 – 0.30 |
| 2 | Vitamin B2 (Riboflavin) | 4.0 – 7.0 |
| 3 | Vitamin B3 (Niacin) | 10.0 – 25.0 |
| 4 | Vitamin B6(Pyridoxine) | 0.5 – 1.5 |
| 5 | Vitamin B12 (Analogue) | 0.10 – 0.30 |
| 6 | Folic acid | 0.05 – 0.30 |
| 7 | Inositol | 70 – 90 |
| 8 | Vitamin K | 0.90 – 1.05 |
Nutrient profile of Spirulina vs other foods
- 180% more calcium than whole milk
- 670% more protein than tofu
- 5100% more iron than spinach
Health benefits of Spirulina
Research on Spirulina’s health benefits has been farranging. In addition to antioxidant and antiinflammatory effects other potential health applications are:
- Protection of the liver and kidneys
- Improvement of blood quality and prevention of anaemia
- Benefits for diabetes
- Reduction in Blood Pressure
- Removal of heavy metals from the body
- Radioprotection
- Antioxidant action
- Relief in allergic reactions
Spirulina has been recommended as a good source of vitamins and minerals, antioxidant and for its potential antiviral and immunological properties. Studies so far suggest that Spirulina is a safe food supplement but its role as a drug remains to be confirmed. More clinical studies should be undertaken to confirm the role of Spirulina as a drug therapy. Spirulina seems to be the most promising strain in the attempt of using unconventional sources to fight nutritional deficiencies.
References
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