Due to all of the above, the abundance of bacteria that produces azoreductases—Bifidobacterium, Lactobacillus, Enterococcus, Clostridium, Eubacterium, and Bacteroides genus [74,75,76], and bacteria that produces NATs could have a relevant impact on the markers that define the response to RA treatment. The gene discussed is NQO1; the disease is rheumatoid arthritis.