Where could I find or compile a comprehensive list of philantropists,
particularly those interested in alternative health care, promoting
healthy lifestyles, and / or the use of meditation and yoga as a means
to achieve optimal health?

http://philanthropy.com/ is the home of The Chronicle of Philanthropy

http://www.worldphilanthropists.org/ is a general philanthropy-related site

http://www.philomath.k12.or.us/phs/luta.html has some information on
researching philanthropists that might be useful to you. It mentions
there is a long list of philanthropists in the book "World Almanac &
Book of Facts" which you can get at the library or from an online book
seller.