There is quite a lot of research to support the use of biotin for hair breakage. Biotin is a B vitamin that is necessary for cell growth. Biotin deficiency leads to hair loss and biotin has even been used in children with genetically brittle hair to improve strength and manageability.
It is important to understand that biotin will not actually stimulate new hair growth. Biotin does, however, prevent breakage and therefore improves overall hair health and thickness. You need at least 3000 micrograms of biotin daily to get the best results AND it can take up to six months to see improvement. This is because hair grows an average of one centimeter per month so you need to be patient.
The good news is that, for nails, the results are much quicker and my patients always comment on nail improvement first. So for thicker hair and stronger nails, consider taking a biotin supplement daily.