I have to respond none. Not because I am lucky or anything. I just work it from the inside out. I take gralic, vitamin B 100, flaxseed, chlorella and biotin daily. I know it sounds like alot but it is working for me very welll. I got my hair cut 3 months age and it is growing just fine. My ends are fab. I told my stylist I do not plan on cuttin gthem until the end of the year I just took and install down and I did shed hair but breakage is minimal. I exercise, watch my diet (even though I celebrated Labor day today) and drink more water than ever in my life my hair is thriving and I look and feel great. IMHO