Energy drinks: any good?

Whether you use them for a boost at work, extra stamina in the gym, or a more vibrant night out, power drinks are the latest answer to hectic modern life. But do they really "give" extra energy, or push your body too far, leaving you drained? Anastasia Stephens tested seven leading energy drinks over a week to find out...

V-Energy Drink

What's in it?

Claiming to "invigorate body and mind", giving a natural energy boost and enhancing concentration, V contains a combination of sucrose, guarana, caffeine and B-vitamins.

Science?

There have been no trials, but the ingredients have well-recognised effects. The 50mg of caffeine in a 250ml can has an adrenaline-like effect, raising heart beat and alertness.

The drink also contains 300mg of guarana, an Amazonian stimulant, which acts like caffeine but causes less anxiety. B-vitamins are added as they are known to help the body produce energy, while sucrose provides the body with immediate fuel.

Does it work?

Drinking a can for my Monday morning pick-me-up, within minutes I felt more alive and awake. It gave me a stronger buzz than my usual cup of coffee. Combined with the high levels of sugar - it tasted sickly - I ended up feeling frenetic and slightly wired. The effect fuelled me until lunch time, after which I felt a definite slump.

Power rating: *****But it seemed to drain my body of reserves.

Lucozade

What's in it?

Claiming to give "brain and body energy", the active ingredients in Lucozade are sugar and caffeine.

Science?

The secret to Lucozade is cramming you with sugar - each 380ml bottle contains 26 per cent glucose syrup. Glucose is the preferred energy source for the brain and nervous system. ECGs of people who have drunk Lucozade have found it boosts mental performance and reaction times.

Does it work?

I tested Lucozade's claims on my way to a meeting: I'd just eaten a heavy lunch so felt mentally slow. In about 10 minutes, I felt my mind becoming more alert. It noticeably helped me with my meeting, but the energy rush made me feel agitated. A few hours later when the sugar left my blood, I was left feeling hungry, agitated and had trouble concentrating.

Power rating: ****A noticeable hit, but I paid for it with a slump.

Purdey's Activation

What's in it? Contains sugar, apple juice, B-vitamins, and the energising herbs damiana, ginseng root and prickly ash bark.

Science?

The sugar and fruit sugars give the body a more sustained release of energy than pure sugar, which usually gives a rush followed by a dip. Ginseng makes the heart work more efficiently for the same energy input and has been shown to enhance mental and athletic performance. Damiana is energising and an aphrodisiac. Prickly ash acts on circulation.

Does it work?

I'd had a light breakfast and, with no morning snacks in sight, I found my concentration waning. It took me 15 minutes to feel the effect of Purdey's and even then it was quite subtle, with no power surge. I felt gently more alert for several hours. The effect gradually and imperceptibly trailed off.

Power rating: ** A subtle boost with no noticeable downside.

Powerade Liquid8 System

What's in it?

The Powerade Liquid8 System contains maltodextrin, glucose, minerals and electrolytes.

Science?

Designed to help prevent dehydration and delay muscle fatigue during exercise, Powerade is isotonic - balanced at the same concentration as your body's natural fluids so it rehydrates you faster than water. Aside from replacing minerals lost in sweat, it fuels you with fast-acting carbohydrates.

Does it work?

I drank the bottle of the azure blue liquid before a workout. It looks like antifreeze but tasted like melted icelollies and wasn't oversweet. It did work: my energy levels remained constant and it kept away the thirst even though I was sweating profusely on a rowing machine.

Power rating: ***

Got me through a workout, but the bright blue colour was hard to stomach.

Red Bull

What's in it?

Each can has 27grams of sugar, around 80mg of caffeine, 1,000g of taurine, glucuronolactone and Bvitamins.

Science? Each can is equivalent to a very strong coffee - it's no wonder Red Bull works. The drink gives the body a massive sugar boost while the caffeine sends levels of adrenaline, surging. It is also high in taurine, an amino acid involved in the function of the heart, brain and eyes, and a sugar, glucuronolactone. Red Bull is banned in some countries due to concerns over the safety of taking in taurine at such high levels.

Does it work?

Took a few cans of Red Bull to a party on Saturday night where it clearly lived up to its name as a stimulant. I was running around boring people with conversation and couldn't stand still. I felt rotten the next day - my stomach reacted badly and I felt the high sugar levels and other ingredients drove my body too far. I had barely drunk any alcohol, yet felt drained and exhausted.

Power rating: *****Gave me a massive energy boost, but my stomach couldn't handle it.

Wellman High Performance

What's in it? Combines fruit juices with guarana, green tea, ginseng, artichoke and vitamins.

Science?

Guarana and green tea are natural sources of caffeine, while studies on ginseng have found it makes energy metabolism more efficient. This drink also contains B-vitamins and the amino-acid tyrosine, nutrients involved in the body's energy production.

Does it work? I tried this before a run in the park. It gave me a subtle lift in energy. Unlike after drinking V, I felt clear and sharp but not wired or "high".

Power rating: ***

Gives a clear lift, without making you feel wired.