Yes, this is absolutely true. One time I started having all sorts of issues with fatigue, numbness & tingling in my extremities, and I saw a neurologist who checked my B vitamins. My B6 levels were off the charts. I was taking some sort of mega women's multivitamin from a vitamin store, drinking pre-workout shakes before going to the gym (I weight lifted a lot a that time) but anyway the shakes contained high B6, I was eating cereal fortified with B vitamins, and it was just way too much B6 in my body. It was over a year before I could even take a multivitamin containing B6 (just a plain women's multivitamin, nothing fancy). Unfortunately, I now do have peripheral neuropathy, but all my vitamin levels are normal, my iron is low but still in the normal range, the cause has been given as idiopathic, which is very frustrating because I just wanted to know what was causing it and be able to fix it and I can't.