What are the dangers of whip its?

I've been doing nitrous oxide for a month now and I haven't noticed any change in my behavior or anything, but I'm still slightly worried that long term use might be damaging. Considering as extensively nitrous oxide is used medically and how it's used fairly regularly at dentists offices, I don't think it'd be an issue. Does it really kill brain cells? As long as I eat good food and replenish my vitamin B12 will I be fine? Please no "drugs are bad" responses, I'm looking for a convincing answer from someone who knows what they're talking about.