What are energy drinks really doing to your body?

Energy drinks are proliferating in food-store fridges but how much caffeine and sugar is in them? And do they really provide consumers with energy? In-depth reporter Mava Moayyed investigates for Fair Go.

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In supermarkets and dairies across the country, there is an eye-watering array of super sweet, highly-caffeinated energy drinks for sale.

Red Bull says it will “give you wings”, drinking Monster will “unleash the beast”, and a can of Mother will “keep the good times spinning morning, noon, and night”.

There is a reason these claims are creatively vague; making actual health or performance claims on a product in New Zealand isn’t easy and must be backed by robust scientific evidence.

The truth is, there are only limited studies to support any health or performance benefits of energy drinks. But the popularity of these concoctions seems to be increasing.

A New Zealand survey found 35% of secondary school students reported consuming an energy drink in the past week, and 12% reported consuming energy drinks four or more times in the previous week. International studies have shown the drinks are particularly popular among young men.

Energy drinks are regulated in New Zealand. The Food Standards Code limits the amount of caffeine to a maximum of 32 milligrams per 100 ml.

Prime Energy drinks, developed and promoted by YouTube megastars Logan Paul and KSI (Olajide Olayinka Williams "JJ" Olatunji) were initially banned in New Zealand for having 57mg of caffeine per 100ml – nearly double the New Zealand limit. But a version with less caffeine has recently been made available here.

Fair Go looked at a range of energy drinks to compare the amount of sugar and caffeine in them. All the 500ml energy drinks we compared had between 150-160mg of caffeine. For comparison, a double shot flat white has 200mg of caffeine.

Coke has far less with the 600ml bottle coming in at 60mg of caffeine.

There is no legal limit on the amount of sugar energy drinks can contain. In the 500ml cans we tested (with the exception of Prime which contains artificial sweetener Sucralose) all the drinks had more sugar than the recommended intake of 6-12 teaspoons a day.

V Blue topped the list with 17.3 teaspoons of sugar.

The separate effects of sugar and caffeine are well-known, but scientists are still discovering what happens when we combine them.

Nutritional physiologist Associate Professor Jennifer Miles-Chan says research has shown the mix of caffeine and sugar can increase stress on the heart muscles. (Artificial sweeteners such as Sucralose have also sparked questions about cardiovascular risks.)

“If you were one of those unfortunate folks who has an undiagnosed heart condition, these drinks would turn from being a kind of high to having real serious medical consequences,” she said.

Recent research has also shown links to increased risk of mental health issues, including depression and ADHD, among children and young people who consume energy drinks.

Miles-Chan, who is the director of the Human Nutrition Unit at the University of Auckland, answered our questions about what these drinks really do to our bodies.

Miles-Chan: There's no recommended amount of caffeine. But there is a recommended maximum intake of caffeine, and in New Zealand, that maximum is set at three milligrams per kilogram of body weight.

So if you are 50 kgs, then that's going to be 150 milligrams per day. If you are 100 kgs, it's going to be 300 milligrams per day.

Caffeine is a central nervous system stimulator that is absorbed through your small intestine and enters into your bloodstream in about 30 to 45 minutes.

That's going to cause adrenaline to be released. It's going to cause your blood vessels to all tighten up. It's going to cause your blood pressure to increase, your heart rate to increase. It's going to give you a little bit of the jitters.

Miles-Chan: Guarana is a vine that grows in the rainforest, and it has these cool little flowers that kind of open up and look like a little eyeball inside, so the name comes from “eye of God”.

Guarana seeds contain about four times the caffeine content as coffee beans.

If you see the ingredient list has both caffeine and guarana listed, it’s basically listing caffeine twice.

Miles-Chan: No, that’s not true! Taurine is an amino acid that the body makes itself. Most of us will get plenty of taurine in our diet so we don't need to consume extra taurine.

There are some claims that taurine has some sort of benefit on the brain, I think primarily because there's lots of taurine circulating around in the brain. But there's very little evidence that getting taurine in your diet, let’s say through an energy drink, will actually increase taurine levels in your brain.

Miles-Chan: Energy drinks sometimes have some B group vitamins. B group vitamins are largely water soluble, and we get plenty of them in our diet.

For the most part, if you overconsume them, they're going to come out in your pee. That's where the yellow pee comes from. So not really going to have much of an effect there.

Miles-Chan: Well, [most of them] contain plenty of sugar so in that respect, you're getting your calories in.

But the caffeine is not giving you a hit of energy. In fact, the caffeine is going to cause your body to use more energy.

The thing that scares me... is that when you combine sugar and caffeine, the heart is under added stress compared to what it would usually be.

Miles-Chan: New Zealand already has some of the toughest regulations around energy drinks. My personal feeling is that putting an age restriction on it isn't going to stop young people from drinking them, in the same way it doesn't necessarily stop young people from drinking alcohol.

[In 2019, Supermarket chain Woolworths voluntarily introduced an age restriction of 16 years on the sale of energy drinks. People may be asked to produce ID at the checkout.]

Miles-Chan: So that's an interesting one. There are terminology issues surrounding that. A lot of the companies will tell you that these drinks aren't addictive [but] there's certainly a dependency that can occur.

A dependency is when the body has a sort of physiological response that is being driven by the drinks. When you take them away, there is consequences.

For example, if you drink a lot of coffee, you may notice headaches or irritability if you stop drinking it. That might be physiological withdrawal.

Miles-Chan: Certainly, they will keep you awake. They're a stimulant. So, if you are needing to avoid sleep, then they would work.

You should consider your reason for picking up the drink. Are you picking up a drink to quench your thirst? Maybe water's a better idea. Are you picking up a drink to give you a caffeine hit? Maybe a coffee is a better idea. Are you wanting to recover from exercise? Maybe a chocolate milk is a better idea.

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