Spirulina's protective properties against cancer
A study of Spirulina's antioxidant effects tested the supplement on 87 people in Kerala, India, who regularly chewed paan tobacco. Paan is prepared from the leaf of the betel tree and various spices, and is typically chewed after meals and ceremonies such as weddings and receptions. Paan tobacco chewers are at increased risk of an oral cancer called oral leukoplakia. Over the course of one year, 45% of the tobacco users who took daily Spirulina supplements saw a complete regression of lesions. While only 7% of people in the placebo group saw a complete regression in tumours in the same period.
Mathew, B., et al. (1995). Evaluation of chemoprevention of oral cancer with Spirulina fusiformis. Nutrition and Cancer, vol. 24, iss. 2.