Things that may prevent or slow Parkinsons???

Hi there, my husband's father was diagnosed with Parkinsons and now I'm wondering just what my husband's odd of getting it are. Is there anything that he can be doing now to try and avoid it? I welcome any thoughts or ideas. I find this site to be such a wealth of intelligent information...not just a site to think of a drug first. Thanks so much for any help anyone might be able to give me in this regard.