Submitted to: Nutrition in Cancer
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/1995
Publication Date: N/A
Interpretive Summary: Oral cancer is one of the commonest forms of cancer with a worldwide distribution. Our recent experience has shown that this form of cancer is a good human model to study for the effect of various dietary nutrients as preventive substances. We selected human subjects suffering from a condition called oral leucoplakia (a non-cancerous, but high risk pre-cancerous condition) and supplemented their diet with 1 gram/day of dried Spirulina (blue-green algae commonly used in Asia as a food supplement) as a source of beta-carotene (source of vitamin A). Our hypothesis was that Spirulina, as a good dietary source of beta-carotene, may be effective in curing oral leucoplakia. Our studies showed that 57% of the subjects had symptomatic and objective improvement with this dietary supplement compared to 7% among those who were given a placebo. These studies strongly support the idea that nutritional supplements rich in carotenoids may be useful in cancer prevention. Further research on other forms of cancer where there is a clearly definable pre-cancerous condition, should be conducted to test the effectiveness of this approach.
Technical Abstract: The blue green microalgae, Spirulina algae, used in daily diets of natives in Africa and America has been found to be a rich natural source of proteins, carotenoids and other micronutrients. Experimental studies in animal models have demonstrated an inhibitory effect of Spirulina algae on oral carcinogenesis. Studies among pre-school children in India have demonstrated Spirulina fusiformis (SF) to be an effective source of dietar vitamin A. We evaluated the chemopreventive activity of SF (1 gm/day X 12 months) in reversing oral leucoplakia in pan tobacco chewers in Kerala, India. The complete regression (CR) of lesions was observed in 20/44 (45%) evaluable subjects supplemented with SF as opposed to 3/43 (7%) in the placebo arm (p<0.0001). When stratified by type of leucoplakia, the response was more pronounced in homogenous lesions: CR was seen in 16/28 (57%) subjects with homogeneous leucoplakia, 2/8 subjects with erythroplakia, 2/4 subjects with verrucous leucoplakia and 0/4 subjects with ulcerated and nodular lesions. Within a year of discontinuing supplements, 9/20 (45%) complete responders with SF developed recurrent lesions. Supplementation with SF did not result in increased serum concentration of either retinol or B-carotene. It was also not associated with any toxicity. This is the first human study evaluating the chemopreventive potential of SF. More studies in different settings and different populations are needed for further evaluation.