So you're talking physical health? How regularly? Once a week? Twice? Once every two weeks? Who did the study?
Masturbating may protect against prostate cancer - 16 July 2003
http://www.newscientist.com/article.ns?id=dn3942
In 1999, the Society for the Scientific Study of Sexuality held a
research conference on the topic of
Masturbation, and from this meeting, chaired by Walter
...
http://www.ejhs.org/volume6/masturbation.html
Why is Female Masturbation Important to Understand[SIZE=-1]
Masturbation is one of the most important subjects to discuss.
... Women in my
research say they can touch to [bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse] with ease in just a few minutes,
...[/SIZE]
http://www.hite-research.com/artmasturbation.html
Amazon.com: Masturbation As a Means of Achieving Sexual Health ...[SIZE=-1]
Masturbation As a Means of Achieving Sexual
Health (Paperback) by Walter O. Bockting (Editor), Eli Coleman (Editor) "ABSTRACT.
Research on
masturbation has
...[/SIZE]
Mastubation: Questions and Answers - sexual health information[SIZE=-1]Sexual
health information discussing
masturbation, which refers to touching
... The National
Health and Social Life Survey and other
research conducted
...[/SIZE]
Male masturbation: Can it affect fertility? - MayoClinic.com[SIZE=-1]
Masturbation generally has no negative effects on
health.
... Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and
Research. AN01189
...[/SIZE]
The Health and Pleasure of Frequent Masturbation[SIZE=-1]SYDNEY - Frequent
masturbation may be really good for you.
Research by Australia's Cancer Council Victoria found that the more often men [bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse] between
...[/SIZE]
There are a few you might like to look at.
As far as I'm aware, there is absolutely no evidence to suggest that masturbation is bad for you, and lots to suggest it is good for you.
Note: Yes, it IS true that certain pathologies result in masturbation to a degree that is physically harmful... but that is not the masturbation responsible for the damage, but rather the underlying psychological, pharmocological, or physical reason for the behaviour