I discovered this a couple of days ago and I am wondering whether it's me and if not, which specific ingredient of the toothpaste causes such reaction. I am using a regular colgate toothpaste, btw.

Sometimes for strengthening my hair, I make herb mixes or use single herbs  that are perfectly drinkable, like camomile or black tea. Only I make them stronger and let them stand for at least 30 minutes. Once I wanted to be quick and brewed the stuff just before washing my hair. Afterwards as I poured some into the palm of my hand in order to use it, it almost burned me. I found this strange and took a sip - it was not at all too hot to drink, only too strong.

Why does the mouth have no problem with temperatures that are too hot for the hand? I can guess part of the answer: we're used to it. Children get lukewarm food, and then we gradually increase the temperature. OK but when I try to let my hands get used to hot water - maybe the palms would, but the backs become rough and red...

I have attended several different types of exercise class over the years, and I'm always instructed to breathe in through the nose and out through the mouth while exercising. No instructor can tell me why.

Is there a scientific reason for this advice?

Heather Shute, Oxfordshire, UK