Natural beta-carotene and cancer prevention
Increasing cancer rates seem to be caused by environmental factors, especially diet. Scientists are examining foods and substances having protective factors. Beta-carotene is one of the most well known natural anti-cancer substances. Over the past twenty years, cancer health authorities, National Cancer Institute and dozens of publicized studies have shown evidence that eating vegetables rich in beta-carotene reduces the risk of all kinds of cancer.
Beta-carotene is the main source of vitamin A for humans. Our bodies convert beta-carotene to vitamin A as we need it. Although very high dosages of vitamin A supplements are toxic, high amounts of beta-carotene from foods and supplements are safe. Spirulina is the richest beta-carotene food known, having over ten times more beta-carotene than any other food, including carrots.
Beta-carotene is one of the most effective substances for deactivating free radicals, which damage the cells, leading to cancer. Free radicals are molecular fragments from environmental pollution, toxic chemicals, drugs, and physical and emotional stress.
Over 100 animal studies confirm Vitamin A and Beta-carotene inhibit the development of various cancers and tumours. Many human studies correlated high Vitamin A intake with decreased cancer risks. 12 Beta-carotene (and not the preformed Vitamin A from animal sources) correlated with lower cancer rates. *13
Over 15 studies from 1975-1986 correlated lower incidence of lung cancer with beta-carotene and vitamin A. One study found the lower the serum level of beta-carotene, the higher the incidence of lung cancer. 14 Nine  studies from 1974-1986 correlated lower digestive tract cancer (oral, stomach, colon, gastrointestinal) with beta-carotene and vitamin A. Two studies with women correlated lower breast cancer and cervix cancer. A five year study in China completed in 1993 with 29,000 people daily dosages of beta-carotene, vitamin E and selenium reduced the incidence of cancer deaths by 13%.
In 1987 Israeli study demonstrated natural beta-carotene is more effective than synthetic. The body better assimilates natural beta-carotene. Beta-carotene in algae and vegetables have greater antioxidant power than synthetic beta-carotene. *17
13 Shekelle, R. B. et al. Dietary Vitamin A and risk of cancer in Western Electric study. Lancer, 1981. 8257:1185-1189.
14 Menkes, et al. Serum Beta-carotene, vitamins A and E, selenium, and risk of lung cancer. Johns Hopkins, N.E. Journal of Medicine, Nov 1986, p. 1250
17 Ben Amotz, A. Presentation to Polysaccharides from microaglae workshop. Duke University, 1987
Anti-cancer tumour effects
Because it is the richest natural beta-carotene food, Spirulina has been tested for anti-cancer effects. The Harvard University School of Dental Medicine reduced oral cancer cells with Spirulina extracts. A beta-carotene solution applied to cancerous tumors in mouths of hamsters reduced the number and size of tumors or caused them to disappear. 18 When beta-carotene extracts was fed to twenty hamsters pre-treated to develop mouth cancer, none developed the disease. Tissue samples contained an immune stimulating substance believed to have destroyed cancer cells before they could multiply.
Evidence linking natural beta-carotene and cancer prevention is impressive. For those who do not eat 4-9 servings of fruit and vegetables daily, Spirulina will add natural carotene insurance.
18.Shwartz, J. Scklar, G. Suda, D. Inhibition of experimental oral carcinogen sis by topical beta-carotene. Harvard School of Dental Med. Carcinogen sis, May 1986, 7(5) 711-715.