的確有人懷疑B2 和葉酸缺乏會增加癌症風險，但是經過試驗否定了（ZT）

Again, based on animal experimental evidence and supported by epidemiologic evidence of connections between diets low in B vitamins and increased cancer risk, a large randomized controlled trial was begun in 1985 in central China, where micronutrient deficiency was common and where rates of cancers of the stomach and esophagus were extraordinarily high. Nonetheless, several years of supplementation with a combination of riboflavin (vitamin B2) and niacin (vitamin B3) had no effect on incidence of upper gastrointestinal cancers. Interest in folic acid (vitamin B9) persisted, though, in part because of its striking effect on neural tube birth defects, coupled with speculation about possible benefits of food fortification for diseases such as colorectal cancer that were inversely associated with diets rich in folate-containing foods and supplements. However, a 7-year randomized controlled trial found that high-dose folic acid supplements actually increased risk of colorectal adenomas. The vitamin B era was over.
如何解釋，還需要進一步研究。