79 citations,
January 2017 in “Dermatology practical & conceptual” Correcting nutrient deficiencies may help with hair loss, but the benefits of supplements without a deficiency are uncertain and could be harmful.
78 citations,
January 2017 in “Skin appendage disorders” Biotin supplements may improve hair and nail growth in people with certain deficiencies or conditions, but there's not enough evidence to recommend it for healthy individuals.
7 citations,
January 2017 in “Indian Journal of Dermatology, Venereology and Leprology” 
71 citations,
January 2016 in “International Journal of Trichology” Biotin deficiency is not a major cause of hair loss in women, so biotin supplements are not likely to be an effective hair loss treatment.
37 citations,
March 2014 in “Journal of Trace Elements in Medicine and Biology” Lower hair zinc and copper levels found in Turkish males with hair loss; higher BMI linked to less hair zinc.
73 citations,
January 2013 in “Annals of Dermatology” People with hair loss, especially those with certain types, have lower zinc levels, and zinc supplements might help.
98 citations,
October 2012 in “Dermatologic Clinics” Eating the right nutrients can improve hair health, but taking extra supplements usually doesn't help unless you have a deficiency.
21 citations,
June 2011 in “Journal of child neurology” Valproic acid and carbamazepine do not change biotin or biotinidase levels but may lower zinc levels, still within normal range.
70 citations,
June 2010 in “Clinics in Dermatology” Certain groups may need vitamin supplements to improve hair health and prevent other health problems.
11 citations,
May 2009 in “Medical Hypotheses” Male pattern baldness is an unintended side effect of the body's use of androgens for muscle growth, especially in those genetically prone to it.
166 citations,
November 2008 in “Expert Review of Endocrinology & Metabolism” Biotin and biotinidase are essential to prevent health issues, and deficiencies require lifelong supplementation.
60 citations,
October 2005 in “Experimental Dermatology” Zinc can both inhibit and stimulate mouse hair growth, and might help recover hair after chemotherapy.
239 citations,
July 2002 in “Clinical and Experimental Dermatology” Low iron and L-lysine levels can cause hair loss in women, and increasing these nutrients can reduce hair shedding.
68 citations,
April 2002 in “Journal of Alternative and Complementary Medicine” Natural 5AR inhibitors effectively improve mild to moderate hair loss in men.
