I could be wrong but I think Entropy means this is a net loss in nutrients and calories, based on the waste it took to produce the egg. The building-blocks needed to make it were already there and if my body needed it it would've taken them directly so I probably wouldn't...? Unless I was starving, which presumably egg production would also decrease to begin with.

But this reminds me of something.

We have bacteria in our colons that produce bio-available B12 but this is downstream of the absorption point. I remember reading theories that we originally obtained this B12 from unsanitary food and water sources (river, pond water, fecal-matter on foods in wild, etc.) Surprisingly a significant chunk of those who eat meat are also deficient of B12 in the modern age.