What's a safe and effective - natural, if possible - product for men to use to prevent falling hair?

Have a healthy diet, keep a good exercise routine and take care not to stress so much. I've read that excessive alcohol and other stimulants like caffeine and tobacco contribute to a bad scalp which can promote hair loss, so best to cut down on those. Also avoid wearing headgear (helmets, caps) for too long, especially if hair is wet. The lack of air and constant rubbing of the scalp will cause breakage of hair.