Obesity and cancer third most important risk factor for cancer in the United States, just behind tobacco and diet (see Figure). Obesity is the source of about 15% of all preventable cancers. In 2018, Chinese researchers performed a systematic review and comprehensive quantitative meta‐analysis of cohort studies reporting body mass index (BMI) and the risk of 23 cancer types, providing epidemiological evidence supporting the association between BMI and cancer risk. The strongest positive association between BMI and cancer risk was found among patients in North America. The mechanisms by which obesity may increase the risk of cancer are not well understood, but it
Diet and cancer Cancer Research UK, "there is currently no evidence that any type of mushroom or mushroom extract can prevent or cure cancer", although research into some species continues. According to the American Cancer Society, although laboratory research has shown the possibility of some connection between soybeans and cancer, as yet there is no conclusive evidence about the anti-cancer effect of soy on human beings. Laboratory experiments have found that turmeric might have an anti-cancer effect. Although trials are ongoing, large doses would need to be taken for any effect. It is not known what, in any, positive effect turmeric has for