Eli5: If every living thing has DNA in its cells, and DNA contains the instructions for functions of life, why do our bodies NOT interact with the DNA that we consume from eating plants and animals?
In: 5
Your body is *really* good at separating “inside” from “outside”. Weirdly, the interior of your digestive tract (inside the stomach, intestines, and colon) are all “outside” your body. The food in there, like cells with DNA, are broken down *outside your body* before they are taken into the real “inside”. So it is rare for large pieces of intact DNA to make it inside your body.
Second, your immune system does NOT appreciate free floating DNA. It will trigger an immune response resulting in the very quick destruction of the DNA.
Third, DNA is only useful inside the nucleus of your cells, where there are special enzymes that can make use of it. Those enzymes however, are really tuned to human DNA. Most random DNA won’t do anything even if it gets into the nucleus.
Lastly, DNA is *gigantic*. Functional DNA is just way too big to get from outside a cell to inside a cell. Imagine someone told you had to eat a spaghetti noodle in one bite, but that spaghetti noodle was a mile long.
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