Office Tales: Milk

Today at work, I was asked why I didn't consume dairy by a co-worker. I paused and then replied, "because it is bad for you."
He was blown away! He had never heard of such insane claims.
...Then he wanted to know why soda (that he is so fond of) is bad for you as if he couldn't believe that either.

I understand most Americans think 'milk does a body good' but I guess I just assumed that they were aware milk, in fact, is not good for you on some level... I couldn't believe that soda is thought of as not bad for you.
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Another co-worker wanted to know why I jog.