This was a big fear for me as I had very long hair going into surgery especially since a surgery in my 20's relieved me of 50% of what I had on my head!
I started taking 5000 mcg of Biotin 1 month prior to surgery. After surgery I added in a band specific (Opurity) multi, and although my hair did get stronger, I still started to shed right at the 3 month mark. This was despite the fact that I tracked every gram of Protein I ate in a day and always made sure I was well over 70g.
Then someone recommended Omega 3. I don't eat fish, and really when I looked at my diet I wasn't getting a lot of Omega 3 from anything. I started taking 3 a day, and oh my god the difference in my hair was amazing after 30 days. The shedding stopped completely and my hair just glowed.
On an added note I can say that the biotin made my nails super strong. The zinc in my Multivitamin removed those tiny white spots that I had for years on my nails as well!
I'd say that the combination of everything contributed to me not losing as much hair after this surgery. But I can't say for sure the magic pill was specifically the omegas, the biotin, the multi or the protein, but either way my hair, skin and nails are the best they have ever been.
Hard to believe with all I used to eat (and it was a lot!) I was so nutritionally void.