This is a pretty bad pun on an old saying (old wive's tale?), but it is true. Some people only read narrowly and thus have narrow minds. Some don't read much, and can become intellectually, morally or wisdomly (a word?) starved (notwithstanding good old common sense which may trump much of what one can read).
And then there is the way in which you eat - I mean read. Chewing is good - somethings don't need it and somethings do. They say that one of the reasons that maybe we have problems with wisdom teeth is because human diets have been getting softer than our ancestors, and hence our jaws are shrinking. You need to read some things you can really get your teeth into. This does mean that reading the odd blog entry is not enough, neither the newspaper (many newspapers have a reading age of a 10 year old, which is ok if you are 10).
I try to read widely, but realise I need to read more (some!) fiction. In his book, Voltaire's Bastards, John Ralston Saul lambasts the Harvard MBA type who reads no fiction and hence has no imagination. Imagination is good for creativity and compassionate living, the ability to empathise. It is also fun in many areas of life.
Lastly, it goes without saying that reading and really chewing (inwardly digesting I think the Anglican prayerbook would say) the bible leads beyond mere canting of verses and shoving things down people's throats, or making misinformed pronouncments on matters of doctrine or morals, to a biblical wisdom - which starts with "fear" of the Lord.