[steven]

This year was particularly hot. Most middle schools had their Undokai (sports day) last week, so I think a lot of schools were worried about the health and safety of their kids. Schools in my area were suggesting their students drink "sports drinks". In Japan the two big "sports drinks" are Pocari Sweat and Aquarius. By sports drinks, I mean drinks that include sodium to replenish what is lost by sweating. I was curious myself, so I asked a lot of my students which they liked better, Pocari or Aquarius. Everyone I asked said they liked Aquarius better. When I asked why, they didn't really have a reason other than it's more popular. Personally speaking, I usually buy Aquarius because it tends to be cheaper (at least in my area).

As far as I know, those two drinks basically consist of water, sodium, and citrus fruit (or their flavors). Japan has like thousands of citrus fruit so I don't really know off hand which are included.

Looking at the wikipedia article on Pocari Sweat, it says that it was created by what appears to be a Pharmaceutical company. The article says the ingredients listed are "water, sugar, citric acid, sodium citrate, sodium chloride, potassium chloride, calcium lactate, magnesium carbonate and flavor" and quotes the Pocari website for that. It says that it has a mild grapefruit flavor-- I think that is pretty accurate.

Personally, I don't see why it wouldn't be safe for a 3 year old. Then again, I'm not a doctor so I wouldn't be listening to me if I were you. I'd ask an actual doctor about it if you're concerned.