A study published in the British Journal of Cancer found that physical activity can reduce the risk of developing polyps by 16%, and developing large or advance polyps by 30%, and the risk of colon cancer by 25%. An analysis of studies involving over 250,000 patients, found less precancerous colon polyps in those individuals who exercised moderately 30 minutes a day. This benefit was found in both men and women. Proposed explanations for this effect is that exercise can boost the immune system and reduces inflammation in the bowel.