Amazon Question. Broad or specific?

What would be the better way to go?
This isn't my niche but you should get the idea.

An Amazon affiliate site selling all products in the health niche eg. stress, sex, weight loss etc..
Or is it better to narrow down to one category eg. stress

Will you be a General Store or An Expert In Your Field? Keywords - Long Tail or Short. Where are you getting your traffic from?
Use the "Search" bar located in the upper left corner of this forum. Spend 2 hours searching for these answers, then the next 2 hours Doing what you just learned.

Good Luck

It depends if you will be a big store or just a little. But for me, i suggest you try being broad. If you use the keyword health, everything about health will try to visit your site. get my point? broad is better.