Any vitamins to slow hair loss in near 40 year old men?

Biotin. The most evidence for a vitamin that helps with hair growth and maintaining hair and nails is in taking biotin. For an adult it is often dosed at 3, 000 - 5, 000 mcgs.
Detoxification. Consider de-tox cleansing and anti-oxidents. It is always a good idea... Consider seeing a holistic doctor. Email dr. Chris shade at www.Quicksilverscientific.Com and say you were referred by dr. Jim wright of four seasons dental spa. He has a 3 month cleanse that is excellent. Good luck with your health and hair growth.