I learned English during my freshman year of high school, Spanish is my native language. I got a 14 on my last MCAT (first time I scored a 10). I am a fan of reading the classics (Dickens, Dumas, Tolstoy, etc) and although I think that helped me tremendously I think that there were 2 other things that were very important:
1) Use the EK technique, practice with their passages under timed conditions giving yourself less time that what you'll have in the real test. I think someone recommended 6 or 7 min. per passage.
2) Put the author on a box
The MCAT does not care about our opinions; it is assessing how well we understand the author's opinion. I would literally read the passage and ask myself "Is this guy a conservative? An anarchist?" I would think about politicians that hold different views or folks that I've met in random places (I once had a whole plane ride sitting next to a libertarian). I would then ask myself, how would that guy answer this question? I would always be tempted to answer what I thought was right but ended up picking the answer that I thought the anarchist would like...
I think that you can definitely improve on VR based on timing and trying to "judge" the author even if you don't read for fun.