Soft drinks were the second biggest contributor followed by all things chocolate as well as energy drinks. Surprisingly, some pastries, cereals and cakes can have “hidden” caffeine.
“There are some very obvious reasons why you don’t want your kids hyped up on caffeine, but there are also some potentially harmful and invisible impacts that you might not be aware of,” said Lisa Te Morenga, a professor of Māori health and nutrition at Massey University.
“I’ve seen adolescents where they showed that high caffeine consumption did increase anxiety, blood pressure.”
The trickle-on effect of poor sleep can spill over into behavioural and learning challenges. Studies also indicate that excessive caffeine can hurt bone development in children who are still growing.
Caffeine is also a diuretic, causing more frequent urination. If you don’t drink additional fluids – preferably water – to top yourself up, then it can put you on the path to dehydration.
Many kids are turning up to school with low hydration levels that typically deplete further throughout the day.
In adults, caffeine – in the right amount – can have positive benefits including increased athletic performance, lower risk of depression, and improved memory and cognitive function, with other benefits, according to Te Morenga.
However, just because it’s good for adults – in the right amount – doesn’t mean that kids will draw the same benefits. And studying kids and caffeine consumption is difficult on a practical level and an ethical minefield.
“Children under-13 should not really be having caffeine and that is a recommendation from the Ministry of Health,” said Massey University’s Ajmol Ali, a professor of exercise science who has studied caffeine and kids.
One of the issues with giving your kids a cup of coffee or a pot of tea is the varied levels of caffeine in an individual beverage. Every person also processes caffeine at different speeds. These two issues can be a problem for adults and children.
For example, the level of caffeine in a coffee will be determined by the beans used, the cup size and the method used to make it.
Filtered or drip coffee tends to have higher caffeine levels than an espresso. Instant coffee probably has the smallest and most reliable amount at around 50mg of caffeine per cup.
“If you don’t realise you’re overindulging, that’s one of the problems,” said Ali, describing a general lack of “caffeine literacy”.
Ali doesn’t drink coffee but occasionally has a Coke or green tea, which has lower levels of caffeine than black tea. But how much caffeine is in your black tea will be determined by how you make it and how strong you like it.
Coke has around 35mg of caffeine per can.
How fast your body purges caffeine from your system depends on your genetics, so caffeine might impact your kids in a similar way to how it impacts you.
“The body produces these enzymes and it clears it out and you pee out the caffeine and it’s good. It’s done what it needed to and it’s gone,” said Ali.
About 45% of people have a lot of these caffeine-expelling enzymes, likely those people who can pound a cappuccino after dinner and sleep perfectly well. Another 45% are considered slow metabolisers of caffeine.
“My enzymes are not as fast at clearing the caffeine, so it stays in my system for longer and that’s part of the reason why if I have caffeine too late, I struggle to sleep,” said Ali.
About 5-10% of people are considered “ultra-slow metabolisers” of caffeine, which can lead to serious health complications when they have too much.
Sometimes this can lead to hospitalisation due to “caffeine-related harm”, Ali said.
Jennifer Douglas, a family nutritionist at Jumpstart Nutrition, remembers drinking tea with her parents at about age 10.
“It was definitely part of my culture and my upbringing,” said Douglas, adding that she probably didn’t like the taste of tea to begin with.
“By the time I was a teenager, they’d say ‘Oh do you want a cup of tea? And you’re like ‘oh yeah’ because that’s what my parents are doing and that seems like an adult thing to do.”
She is trying to hold off introducing caffeinated drinks to her children, aged 12 and 8.
“I’ve offered them herbal teas but I haven’t offered them normal tea, mainly because I know they’re underage.
“I think they’ve got plenty of energy. I wouldn’t want to exacerbate their energy.”
They’ve also tried at least a few sips of Coke because Douglas doesn’t want to “demonise” any food or drink, which can have the opposite effect of kids overindulging in it whenever they can get the opportunity.
Caffeine is an occasional issue for Douglas’ teenage clients, especially for those who are having trouble with sleep and anxiety.
The growing array of energy drinks often marketed to teenagers can have a big impact with many teenagers unaware of how long caffeine can stay in the system. Douglas recommends stopping caffeine eight hours before bed.
“We just have to have open conversations around what’s happening,” she said.
“So think about what types of things you might be buying after school at the dairy with your friends, maybe choosing something that’s not caffeinated so that it doesn’t affect your sleep later on.”
Douglas said parents should also have non-judgmental conversations about how alcohol and caffeine can interact. Alcohol is a depressant that causes sleepiness, whereas caffeine will keep you awake.
“With alcohol, [caffeine] outweighs the sedative effects of alcohol, so it means they’re more likely to drink more...”
“If they’re drinking more alcohol, they’re more likely to be at risk of risky behaviours or getting unwell.”
