Thanks for your replies.
I made a lil observation on the results that google is displaying.
for example, you are looking for 'vitamins'
you will see that most results are showing this url format:
www.samplehealthsite/vitamins
www.samplehealthsite/vitamins/someinfohere
www.samplehealthsite/someinfohere/vitamins
i wonder if i will rank higher even if i use:
www.vitamins.myhealthsitedomain.com/infoaboutvitamins