My answer to Why is L-Lysine so good for treating acne and hair loss?
Answer by Nature Crazy:
Lysine inhibits MMP-9 which is a collagenase enzyme that degrades hair and skin follicles. It also helps lower Lp (a) levels which are typically elevated in MPB sufferers.
There are other ways of lowering Lp (a) levels through a variety of other supplements or diet choices but overall Lysine is a great choice. Vegetarians should definitely be supplementing with Lysine regularly.