Energy "shots" and energy drinks which contain high levels of caffeine are not suitable for children, young teenagers, pregnant women and people sensitive to caffeine, food safety officials say.
The New Zealand Food Safety Authority (NZFSA) today underscored its existing advisory on caffeine, after commissioning a new risk profile.
It warns that when consumed in high doses caffeine can lead to irritability, anxiety, tremors, dizziness and insomnia.
The Environmental Science and Research (ESR) study said some people may experience short-term anxiety effects if consuming more than 3mg of caffeine daily for each kilogram of body weight.
For an adult, this would mean drinking less than two standard cups of coffee, other than instant coffee, or four cups of tea a day.
For most healthy adults, up to 400mg of caffeine in total a day - equivalent to four lattes - appeared to have no ill effects, researchers said, but there were no studies for chronic effects of caffeine consumption by children.
There was evidence that caffeine consumed by a pregnant woman could affect the growth of her baby.
Australia is reviewing scientific evidence on effects of caffeine consumption and does not allow Australian-made energy drinks and "shots" with high caffeine levels to be sold.
But the same drinks made in New Zealand are freely sold because trans-Tasman trade rules permit their import.
New Zealand authorities are expected to work with the Australians on a joint standard for regulation of energy drinks and shots.
ESR noted in its review of the scientific literature that there were significant information gaps.
There were 28 energy drinks (75mg to 240mg of caffeine per drink) and 16 energy shots (10mg to 300mg of caffeine per shot) on sale on this side of the Tasman, cola drinks had 145mg/litre, and hot drinks averaged 80mg (expresso) 99mg (latte) and 55mg (tea).
But there was a lack of knowledge of energy drink and energy shot consumption in New Zealand, weak evidence of adverse effects on which to base safety levels and lack of evidence for the health effects of frequent high caffeine intakes for children and adults.
Baseline intakes calculated from dietary surveys -- mostly before energy shots became widespread -- showed 73 percent of children consumed caffeine through tea and cola-type drinks.
Auckland University of Technology nutrition expert Professor Elaine Rush said that the consumption of caffeine-containing products had risen exponentially and energy shots added to the consumer demand for caffeine.
Community debate should be about the need to protect children and support parents through regulation, she said.
An adjunct professor of nutrition at Massey University, Professor John Birkbeck, said there were health issues posed by the energy drinks.
"The adverse effects of caffeine under these circumstances can be a serious problem," he said.
"The NZFSA should ... seek ways to persuade industry to modify the marketing and even the composition of these drinks".
Energy drinks are covered by a trans-Tasman food standard, but the "shots" had since become widely available and on this side of the Tasman are sold under the NZ supplemented food standard and have to be labelled with how much caffeine they contain, and advice the product is not recommended for children, lactating women, or people sensitive to caffeine.