>> “No, it doesn’t regrow - once it’s gone, it’s gone.” <<
Depends on why it’s gone.
Condroitin Sulphate promotes regrowth for about 2/3 of people.
That's more of an oil to promote easier moving of bones at joints. Look what's in that - I would be dead - shell fish oil. Shell fish puts me in the hospital. See, I thought that might help my bone on bone situation move easier - then, I'm standing in the drug store and reading the ingredients and put the bottle back on the shelf - I didn't dare take that. That was a big disappointment. I have a permanent scar on my arm where the hospital did an iodine test. Man, did I fail that test. Before that was over, my skin rotted out where they put the iodine under the skin. That wound had to heal from the inside out and it is a white spot as it took all the pigment out of that spot.
No hospital can give me iodine in anything - it's on every medical chart I have. Shrimp, crab, clam, now that is poison to me. I still wish I could take that Condroitin Sulphate.
Just out of curiosity, where did you go to medical school?