Context: I'm 31 and have been dealing with hair thinning for about two years. Tried biotin, collagen, iron pills, all of it. Some helped a little, nothing was dramatic. A nutritionist I follow online mentioned that most hair loss in women under 35 comes down to depleted iron, B12 and retinol, and that synthetic versions absorb poorly compared to food-based sources. Started these and within 5 weeks the clumps in the shower drain got noticeably smaller. My ponytail feels thicker. I know that sounds small but if you've dealt with hair loss you know it's not small at all.