"Energy drinks are not recommended for children and they already have to carry a warning on pack. We're simply choosing to proactively put this recommendation into effect in our stores and that's why you'll need to be 16 years or older to buy energy drinks at Countdown."
Supermarkets in Britain, including Asda, Sainsbury's and discount retailer Aldi, have introduced similar measures, requiring children to prove they are at least 16 at the time of checkout.
The Ministry of Health does not recommend energy drinks for young people because of the high amounts of caffeine and sugar. There have been warnings of the danger associated with high caffeine consumption.
In the past few years there have been a number of cases in recent years of young people dying after consuming too many energy drinks in a short timespan.
In 2017, a 16-year-old in the United States died after drinking a large bottle of Mountain Dew, a McDonald's latte and an energy drink within less than two hours.
In 2013, a New Zealand mother of eight died after drinking too much Coke. A coroner found Natasha Harris - who drank up to 10 litres of Coke each day - died from a cardiac arrest due to high levels of caffeine. She was 30.
Consumer NZ head of research, Jessica Wilson, told the Herald the decision was a good move.
"Energy drinks are heavily marketed. But they contain caffeine and are often packed with sugar, and they're not a product you want your kids consuming.
"Countdown's move comes after UK supermarkets have imposed a similar ban.
"It's a small step but it may help to raise awareness about the high-sugar content of these types of drinks."
The Food Standards Code restricts how much caffeine can be added to cola-type soft drinks and energy drinks.
Foods containing added caffeine must also have a statement on the label that the product contains caffeine. Foods containing guarana - a South American plant with high levels of natural caffeine - must also be labelled as containing caffeine. This is to help people avoid caffeine either for themselves or their children.
A Food Standards Australia New Zealand Working Group study found there was evidence of increased anxiety levels in children at doses of 3 mg of caffeine per kilogram of body weight per day.