Gun ownership and suicide

I've been doing some research on firearms and suicide rates across states and countries. It appears as though across states in the US, higher gun ownership is strongly correlated with higher overall suicide rates (and gun suicide rates). [1] This would suggest that either the people who own guns tend to be more suicidal (causality) or that suicidal people tend to own guns (reverse causality). 

However, there is no correlation between international gun ownership and international suicide rates. [2] For example, while Canada has a gun ownership rate far lower than that of the US, it has a near identical suicide rate. Additionally, countries like Japan have a suicide rate near twice that of the US despite have virtually no gun ownership. 

These conflicting results certainly are interesting, but the tendency for gun owners to committ suicide more often than non-gun owners could possibly be a correlation without a causation. For example, as (M.P) has noted in his book, 'The Conscience of a Young Conservative", the amount of country music played on the radio is significantly correlated with higher suicide rates even when gun availability, poverty, and other factors are controlled for. [3] Additionally, non-coastal western states have the highest suicide rates in the country. [4] Could it be that geography is driving the correlation? After all, rural living people tend to own guns and listen to country music more often than people living in urban settings. 

Overall, the causal relationship, or lack thereof, between gun ownership and suicide isn't entirely clear. However, even if increased gun ownership was proven to increase the suicide rate, would that be any justification for restricting it? I personally don't think so. If firearms caused people to kill themselves, than it still wouldn't be a public health issue and thus not a problem worthy of government intervention. Moreover, any intervention would necessitate the restriction of firearm ownership, which is inherently a violation of the 2nd amendment of the Bill of Rights and people's right to choose to own a firearm. 

What do you think?

Citations:

[1]http://marginalrevolution.com/marginalrevolution/2013/11/firearms-and-suicides-in-us-states.html
[2]http://www.law.harvard.edu/students/orgs/jlpp/Vol30_No2_KatesMauseronline.pdf
[3] http://www.jstor.org/discover/10.2307/2579974?uid=3739888&uid=2&uid=4&uid=3739256&sid=21103901015353
[4] http://www.cdc.gov/ViolencePrevention/images/suicidestats/USmap_2009_lrg.gif