The total bacteria mass [they] find represents about 0.3% of the overall body weight, significantly updating previous statements that 1%–3% of the body mass is composed of bacteria or that a normal human hosts 1–3 kg of bacteria [NIH. NIH Human Microbiome Project defines normal bacterial makeup of the body. Natl Institutes Heal 2012. (accessed January 3, 2015). link 5th paragraph from top].