The Surprising Amount of Bacteria Living Inside Our Bodies
The bacteria vs human cells myth. Have you ever heard that we are 10 times more bacteria than human and felt skeptical? You should be. Find out why here.
More people have been questioning this and a recent article has given a new estimation.
Where does this 10:1 ratio come from?
The 10:1 myth comes from a publication in 1972 by the microbiologist Thomas Luckey. He estimated that our gut contains around 10^14 bacteria, by assuming that there are 10^11 bacteria in a gram of feces, and scaling it up according to the one-liter volume of the gastrointestinal tract.
In reality, bacteria are not evenly spread in the body, which makes this way of measuring not the most accurate. But fear not, we’ve got a new estimation!
New Estimated Ratio 1.3:1
In a review of 2016, Milo and colleagues came up with an updated and more scientifically accurate estimate of the bacteria vs human cells ratio: 38 trillion microbial cells (3.8x10^13) versus 30 trillion human cells (3x10^13), which leads to a 1.3:1 ratio.
Interestingly, the contribution of bacteria accounts for only 200g, which is about 0.3% of the body weight of the average 70 kg male.
From this it was concluded that the bacteria vs human cells ratio in our body is closer to 1:1 than 1:10. This new estimation is still pretty amazing and does not mean that microbiota has less importance for our health. Continue reading for more in-depth information on how researchers actually came to this new estimation in the full blog post.
