High-salt environments such as salt evaporation ponds and salt lakes.
Beta carotene, other carotenoids (including alpha carotene, lutein, and lycopene), glycerol, protein.1
Dunaliella salina is a genus of one-celled green microalgae first discovered in 1838 in southern France.2 It is often referred to as a halophile (literally, “salt-loving”) alga because it grows only in high-salt marine environments. Throughout the 1800s, after its first recorded discovery, a number of other biologists also independently discovered this form of algae. It was found in various locations in Europe and Algiers.3 In the early 1900s, even without the advanced technology of today, scientists recognized that Dunaliella contained beta carotene and thus had potential commercial value as a food or nutritional supplement. Although it is technically a green microalgae, the carotenoids (which are pigments) can mask the chlorophyll, at times giving this alga a red or orange hue.4
The key to Dunaliella’s high carotenoid content is its saline environment. The higher the salinity, the greater the beta carotene concentration.5 This organism’s saline requirements also make it easier to grow, because it has few natural competitors in the high-salt environment. Conditions are easily controlled for commercial production. Manipulation of salinity and light conditions, and restriction of nutrients, can stimulate formation of more beta carotene.6
The first commercial enterprise to cultivate Dunaliella for its beta carotene was founded in 1966 in the Soviet Union. Within 10 years, commercial research projects were begun in Australia. Today Australia is one of the world’s leading producers of beta carotene from Dunalliella salina,7 the most common species of this algae. Dunaliella is also cultivated in Israel, China, and the United States. Dunaliella powder is used by the aquaculture industry as a food coloring to give shrimp and farmed salmon an attractive pink hue. The beta carotene from Dunaliella is used as a natural food coloring agent in processed foods and cosmetics. The most valuable use of Dunaliella’s beta carotene is perhaps in nutritional supplements.
One of this alga’s most valuable characteristics is its antioxidant effect. In one recent rat study, for example, markers of antioxidant activity were greatly increased in rats receiving natural beta carotene from Dunaliella.8 Another study focused on the antioxidant effects of Dunaliella in eye health. In this mouse study, researchers demonstrated that the algae can protect the cornea from UVB-induced radiation damage. It does so by decreasing oxidation and increasing antioxidant activity in the cornea.9
This salt-loving microalgae also has beneficial effects on immune health. In a study of rats with cancer, Dunaliella extract stimulated two immune defense processes: spleen cell proliferation and tumor necrosis factor. (The cancer was inhibited by about 55%).10 Rainbow trout given Dunaliella in their diet show enhanced immune function, with increased phagocytosis and increased lysozyme activity.11
Dunaliella has also attracted the interest of cancer researchers. When rats with fibrosarcoma were given freeze-dried Dunaliella salina, their tumors showed signs of regression.12 Mice with cancer in the upper digestive tract were given high doses of Dunaliella extract; their cancer was inhibited by 55%.13 Mice with breast tumors also benefited from Dunaliella treatment; they had significantly fewer tumors than mice who were not given Dunaliella.14 In vitro studies also show promise for Dunaliella as a potential cancer treatment. An extract of this microalgae exposed to human lung cancer cells decreased cancer cell proliferation by 48% by inducing cell death in the first stage of cell division.15 Extracts of Dunaliella are also effective against skin cancer cells in vitro, inducing cell death.16
Another area of Dunaliella research is in liver health, where this alga shows great potential. In two separate experiments, researchers demonstrated that Dunaliella salina protects against liver toxicity in rodents. In the first, Dunaliella was shown to protect the liver by increasing antioxidant activity and decreasing lipid peroxidation.17 In the second, it was shown that the more Dunaliella given to rats, the greater the protective effect.18 Yet another rodent study showed that Dunaliella salina protected against liver damage. In this study, researchers concluded that the mixed carotenoids present in the algae conferred a greater benefit than both natural beta carotene alone or synthetic beta carotene.19
Dunaliella also shows potential benefits for arterial health. Researchers have demonstrated that it can reduce the vascular smooth muscle cell proliferation associated with restenosis (narrowing of the arteries).20 This is supported indirectly by another study showing that high blood levels of carotenoids (such as those found in Dunaliella) can protect against the development of atherosclerosis.21 Another way Dunaliella may help prevent atherosclerosis is through its ability to reduce the oxidative stress associated with high cholesterol. After inducing high cholesterol and triglycerides in rats, oxidative stress – and antioxidant levels – increased as a result. When Dunaliella was administered, antioxidant levels returned to normal.22 (The same study found that Dunaliella may also help protect against hypothyroidism.)
One of the most significant findings in this field of research bodes could well create increasing demand for Dunaliella. Researchers have established that beta carotenes from natural sources such as algae and plant foods are more effective and confer greater health benefits than synthetic beta carotene.23
1 Bishop, W.M., and Zubeck, H.M. Evaluation of microalgae for use as nutraceuticals and nutritional supplements. Journal of Nutrition and Food Sciences. 2012. 2:147.
2 Oren, A. A hundred years of Dunaliella research: 1905–2005. 2005 July 4.
5 Farahat N., et al. Optimization of salt concentrations for a higher carotenoid production in Dunaliella salina (Chlorophycceae). Journal of Phycology. 2011. 47 (5), 1072-1077.
6 Oren, A. A hundred years of Dunaliella research: 1905–2005. 2005 July 4.
7 http://www.bsb.murdoch.edu.au/groups/beam/BEAM-Appl0.html , accessed June 10, 2013.
8 Chidambara Murthy, K.N. In vivo antioxidant activity of carotenoids from Dunaliella salina–a green microalga. Life Sciences. 2005. 76 (12), 1381-1390.
9 Tsai, C.F., et al. Protective effects of Dunaliella salina – a carotenoids-rich alga – against ultraviolet B-induced corneal oxidative damage in mice. Molecular Vision. 2012. 18, 1540-1547.
10 Xue, LX. Experimental study on extract of Dunaliella salina in preventing NSAR-induced cancer of proventriculus in mice. Zhonghua Yu Fang Yi Xue Za Zhi. 1993. 27 (6), 350-353.
11 Amar, E.C., et al. Enhancement of innate immunity in rainbow trout (Oncorhynchus mykiss Walbaum) associated with dietary intake of carotenoids from natural products. Fish & Shellfish Immunology. 2004. 16 (4), 527-537.
12 Raja, R., et al. Protective effect of Dunaliella salina (Volvocales, Chlorophyta) against experimentally induced fibrosarcoma on wistar rats. Microbiological Research. 2007. 162 (2), 177-184.
13 Xue, LX. Experimental study on extract of Dunaliella salina in preventing NSAR-induced cancer of proventriculus in mice. Zhonghua Yu Fang Yi Xue Za Zhi. 1993. 27 (6), 350-353.
14 Nagasawa, H., et al. Inhibition by beta-carotene-rich algae Dunaliella of spontaneous mammary tumourigenesis in mice. Anticancer Research. 1989. 9 (1), 71-75.
15 Sheu, M.J., et al. Ethanol extract of Dunaliella salina induces cell cycle arrest and apoptosis in A549 human non-small cell lung cancer cells. In Vivo. 2008. 22 (3), 369-378.
16 Mo, E., et al. Anticancer effect of Dunaliella salina under stress and normal conditions against skin carcinoma cell line A431 in vitro. Iranian Journal of Fisheries Sciences. 2012. 11 (2), 283-293.
17 Hsu, Y.W., et al. Protective effects of Dunaliella salina–a carotenoids-rich alga, against carbon tetrachloride-induced hepatotoxicity in mice. Food and Chemical Toxicology. 2008. 46 (10), 3311-3317.
18 Chidambara Murthy, K.N., et al. Protective effect of Dunaliella salina–A marine micro alga, against carbon tetrachloride-induced hepatotoxicity in rats. Hepatology Research. 2005. 33 (4), 313-319.
19 Murthy, K.N. Comparative evaluation of hepatoprotective activity of carotenoids of microalgae. Journal of Medical Food. 2005. 8 (4), 523-528.
20 Sheu, M.J., et al. Molecular mechanism of green microalgae, Dunaliella salina, involved in attenuating balloon injury-induced neointimal formation. British Journal of Nutrition. 2010. 104 (3), 326-335.
21 Karppi, J., et al. Serum carotenoids reduce progression of early atherosclerosis in the carotid artery wall among eastern Finnish men. PLoS One. 2013. 8 (5). doi:10.1371/journal.pone.0064107
22 Bansal, M.P. and Jaswal, S. Hypercholesterolemia induced oxidative stress is reduced in rats with diets enriched with supplement from Dunaliella salina algae.American Journal of Biomedical Sciences. 2009. 1 (3), 196-204.
23 Chidambara Murthy, K.N. In vivo antioxidant activity of carotenoids from Dunaliella salina–a green microalga. Life Sciences. 2005. 76 (12), 1381-1390.
1. Evaluation of microalgae for use as nutraceuticals and nutritional supplements
Bishop, W.M., and Zubeck, H.M. Journal of Nutrition and Food Sciences. 2012. 2:147.
In this review article, the authors looked at a variety of microalgae for their nutritional and therapeutic potential. Dunaliella, one of the varieties examined, is rich in carotenoids, primarily beta carotene, which has been demonstrated to scavenge free radicals and neutralize reactive oxygen species. It also supports immune response, promotes intracellular communication, and protects against abnormal cell growth. The natural beta carotene in Dunaliella has been shown to be superior to synthetic forms; for instance, certain antioxidant enzymes in Dunaliella beta carotene are more effective. Other beneficial carotenoids present in Dunaliella include alpha carotene, lutein, and lycopene. Dunaliella is also shown to protect the liver. In vitro multigenerational animal studies demonstrate the safety of this microalgae in the diet.
2. Protective effects of Dunaliella salina, a carotenoids-rich alga, against ultraviolet B-induced corneal oxidative damage in mice
Tsai, C.F., et al. Molecular Vision. 2012. 18, 1540-1547.
In this animal study, researchers examined the potential for Dunaliella salina to mitigate UVB damage on the cornea. Mice were exposed to UVB radiation resulting in corneal ulcers, cell exfoliation, and corneal surface roughness. After the radiation, one group of the mice was given Dunaliella salina for eight days. The mice were then euthanized and their corneal tissue examined further. In corneal tissue of mice given Dunaliella, one particular oxidant showed decreased activity, while specific antioxidants showed increased. In the control mice (not given Dunaliella) the opposite was observed. Researchers conclude that Dunaliella salina likely protects corneal damage from UVB radiation by decreasing oxidation and increasing antioxidant activity.
3. Hypercholesterolemia induced oxidative stress is reduced in rats with diets enriched with supplement from Dunaliella salina algae
Bansal, M.P. and Jaswal, S. American Journal of Biomedical Sciences. 2009. 1 (3), 196-204.
In this rat study, researchers looked at Dunaliella salina’s effect on high cholesterol and deiodinase, an enzyme involved in thyroid hormone production. Rats were fed a special diet to increase their cholesterol and triglycerides, which led to increased antioxidant activity and increased lipid peroxidation. Thyroid hormone levels were also affected. When rats were given Dunaliella salina, antioxidant levels and thyroid hormone levels were normalized. The results suggest Dunaliella salina may be of benefit in the prevention of high cholesterol and hypothyroidism.
4. Anticancer effect of Dunaliella salina under stress and normal conditions against skin carcinoma cell line A431 in vitro
Mo, E., et al. Iranian Journal of Fisheries Sciences. 2012. 11 (2), 283-293.
In this in vitro study, researchers looked at the effect of Dunaliella salina extracts on skin cancer cells. One sample of the algae was cultured under normal conditions; another was cultured under stress conditions (e.g., high salinity, light conditions, etc.). They then exposed skin cancer cells to varying concentrations of each extract at several different time intervals. All cancer cell samples exposed to Dunaliella experienced cell death to varying degrees. Researchers learned that the Dunaliella grown under stress conditions was more effective (i.e., the median lethal dose against cancer cells was lower) as compared to the Dunaliella grown under normal conditions. Researchers believe this is because the stressful growing conditions produce more plant compounds that are effective against cancer.
5. Molecular mechanism of green microalgae, Dunaliella salina, involved in attenuating balloon injury-induced neointimal formation
Sheu, M.J., et al. British Journal of Nutrition. 2010. 104 (3), 326-335.
Narrowing of the arteries (restenosis) is believed to be caused by too much proliferation of special cells called vascular smooth muscle cells. In this experiment, researchers looked at the effects of Dunaliella salina on this phenomenon. They demonstrated that Dunaliella reduced cell proliferation in a dose-dependent manner, with apoptosis possibly being one of the mechanisms involved. Researchers conclude that Duniella may be of therapeutic or preventive benefit in cases of restenosis.
6. Protective effects of Dunaliella salina, a carotenoids-rich alga, against carbon tetrachloride-induced hepatotoxicity in mice
Hsu, Y.W., et al. Food and Chemical Toxicology. 2008. 46 (10), 3311-3317.
In this mouse study, mice were given regular doses of either Dunaliella salina or silymarin for eight weeks. Liver damage was then induced, and key markers examined. In control mice, liver damage was identified by the increase of ALT, AST, and ALP detected in the blood, along with a decrease in antioxidant activity in the liver. Mice who were given either Dunaliella or silymarin showed the opposite; ALT, AST, and ALP were decreased, and antioxidant markers were increased. In addition, Dunaliella-fed mice had fewer liver lesions. Researchers conclude that Dunaliella helps protect the liver by increasing antioxidant activity and decreasing lipid peroxidation.
7. Protective effect of Dunaliella salina, a marine microalga, against carbon tetrachloride-induced hepatotoxicity in rats
Chidambara Murthy, K.N., et al. Hepatology Research. 2005. 33 (4), 313-319.
Researchers cultivated Dunaliella salina under stress conditions in order to stimulate greater beta carotene formation. The enhanced Dunaliella was fed to rats for two weeks, and then toxins were given to them to induce liver damage. Rats who were given higher amounts of Dunaliella received greater liver protection than rats who received less or no Dunaliella. Researchers conclude that because Dunaliella contains more than one isomeric form of beta carotene, it offers greater protection than synthetic beta carotene, which contains only one. The carotenoid xanthophyll, also found in Dunaliella, may also play a role in liver protection.
8. Ethanol extract of Dunaliella salina induces cell cycle arrest and apoptosis in A549 human non-small cell lung cancer cells.
Sheu, M.J., et al. In Vivo. 2008. 22 (3), 369-378.
In this in vitro study, researchers treated human lung cancer cells with Dunaliella salina extract. After 24 hours, cell proliferation decreased by 25%. After 48 hours, it decreased by 48%. The extract worked by inducing apoptosis (cell death) in the first phase of cell division. Researchers believe Dunaliella shows promise as an antiproliferative substance.
9. Protective effect of Dunaliella salina (Volvocales, Chlorophyta) against experimentally induced fibrosarcoma on wistar rats
Raja, R., et al. Microbiological Research. 2007. 162 (2), 177-184.
Researchers induced fibrosarcoma (a malignant tumor of the connective tissue) in rats and then gave them freeze-dried Dunaliella salina. The Dunaliella lowered markers such as catalase, superoxide dismutase, AST, and ALT. Most significantly, the tumor tissue exhibited signs of regression. Two types of beta carotene were identified in the freeze-dried Dunaliella and together may be responsible for the observed effects.
10. Comparative evaluation of hepatoprotective activity of carotenoids of microalgae
Murthy, K.N. Journal of Medical Food. 2005. 8 (4), 523-528.
In this study two types of algae, Spirulina plantensis and Dunaliella salina, were examined for the effects of their carotenoids on liver function. Rats were divided into five groups: those fed Spirulina, those fed Dunaliella, those given no algae but in whom hepatic damage was induced, those fed synthetic beta carotene, and a control group. Typical liver function tests were conducted, including SGOT, SGPT, ALP, and others. While Spirulina demonstrated protective effects, Dunaliella across the board showed the most protection against liver damage. Researchers conclude that the mixed carotenoids in Dunaliella have a greater effect than either natural beta carotene by itself or synthetic beta carotene.
11. In vivo antioxidant activity of carotenoids from Dunaliella salina, a green microalga
Chidambara Murthy, K.N., Life Sciences. 2005. 76 (12), 1381-1390.
In this rat study, researchers looked at the effects of Dunaliella salina on oxidative stress. Rats were divided into four groups: those treated with 125 microg/kg body weight of powdered Dunaliella salina, those treated with 250 microg/kg body weight of powdered Dunaliella salina, those treated with 250 microg/kg body weight of synthetic beta carotene, and those treated with a toxin. A variety of antioxidant markers were tested across all groups. The natural carotenoids from Dunaliella were significantly more effective at inducing antioxidant activity than synthetic carotene. Researchers believe Dunaliella may have beneficial applications as a food additive and in dietary supplements.
12. Enhancement of innate immunity in rainbow trout (Oncorhynchus mykiss Walbaum) associated with dietary intake of carotenoids from natural products
Amar, E.C., et al. Fish & Shellfish Immunology. 2004. 16 (4), 527-537.
In a nine-week study, researchers examined the effects of dietary cartenoids on the immune system of rainbow trout. The trout were divided into three groups: those given a control diet, those given a diet containing 100 mg/kg beta carotene from Dunaliella salina, or those given a diet containing 200 mg/kg astaxanthin from red yeast Phaffia rhodozyma. Both carotenoid groups showed increased immune response detected in body fluids and increased phagocytosis (the process of immune cells engulfing and breaking down foreign invaders). Only the Dunaliella group showed increased activity of lysozymes (enzymes that destroy cell walls of bacteria). Researchers conclude that carotenoids from both Dunaliella salina and Phaffia rhodozyma are helpful in supporting immune response in rainbow trout.
13. Experimental study on extract of Dunaliella salina in preventing NSAR-induced cancer of proventriculus in mice
Xue, LX. Zhonghua Yu Fang Yi Xue Za Zhi. 1993. 27 (6), 350-353.
Researchers looked at the effects of Dunaliella salina extract on squamous cancer cells in mice. Cancer was induced in the proventriculus (a portion of the upper digestive tract) in mice. Researchers discovered that high doses of Dunaliella extract inhibited the cancer by approximately 55%. They achieved similar, but not quite as great, results with beta carotene. Both Dunaliella extract and beta carotene also increased spleen cell proliferation and creation of tumor necrosis factor (which helps regulate the immune system). Researchers conclude that cell immunity was increased with treatment of both substances.
14. Inhibition by beta-carotene-rich algae Dunaliella of spontaneous mammary tumourigenesis in mice
Nagasawa, H., et al. Anticancer Research. 1989. 9 (1), 71-75.
Researchers looked at the effects of Dunaliella on the formation of breast tumors in mice. The mice were given powdered Dunaliella bardawil and an oil solution containing Dunaliella salina. A control group was given no supplementary Dunaliella. The mice receiving the supplements had significantly fewer breast tumors than the control group. Endocrine markers did not appear to be affected by the Dunaliella; thus researchers conclude the mechanism of action is not through the endocrine system, but some other pathway.
15. Effect of beta-carotene on immunity function and tumour growth in hepatocellular carcinoma rats
Cui, B., et al. Molecules. 2012. 17, 8595-8603.
In this study, researchers examined the effects of beta carotene in rats with liver cancer. Rats were given either low, medium, or high doses of beta carotene. A control group was given no beta carotene. After 30 days, various blood markers (including NK, IL-2, tumor necrosis factor alpha, and more) showed the effectiveness of the treatment; tumor growth was also slowed or stopped. When the liver tissue was examined, the findings showed that the beta carotene lessened the tissue damage from the cancer. In rat models, beta carotene shows promise for boosting immune function and hampering tumor growth. While Dunaliella was not studied directly, it is rich in beta carotene and thus it can be expected to have a similar effect.
16. Epidemiologic evidence for beta-carotene and cancer prevention
van Poppel, G., and Goldbohm, R.A. The American Journal of Clinical Nutrition. 1995. 62, 1393S-1402S.
This review looked at epidemiological studies involving the relationship between dietary beta carotene intake and various forms of cancer. (While the beta carotene in Dunaliella was not specifically considered, it is a rich dietary source of beta carotene.) Researchers concluded several things from their review. First, a diet rich in beta carotene from plant foods and/or high blood levels of beta carotene are associated with a lower risk of lung and stomach cancers. There is a moderately reduced risk of colon cancer. There is no association with beta carotene and reduced risk of breast or prostate cancers. Furthermore, while the data showed promise for high dietary beta carotene intake and lower risk of esophageal cancer, more study is needed.
17. Serum carotenoids reduce progression of early atherosclerosis in the carotid artery wall among eastern Finnish men
Karppi, J., et al. PLoS One. 2013. 8 (5). doi:10.1371/journal.pone.0064107
In this study involving 840 men, researchers looked at the effects of blood levels of carotenoids on the development of atherosclerosis. While the study did not look at Dunaliella, it is worth noting that Dunaliella is rich in natural carotenoids. Sonograms were performed to assess the thickness of carotid artery walls; serum blood levels of carotenoids were tested at the same time. Study participants underwent initial tests at the beginning of the study period and then again 7 years later. Adjusting for BMI, blood pressure, smoking and exercise habits, and other factors, artery wall thickness was inversely associated with carotenoid blood levels. Researchers conclude that carotenoids may help protect against the development of atherosclerosis.