Evidence to establish a safe consumption limit is unavailable

High-energy drinks have three principal constituents: caffeine, taurine and glucuronolactone. Caffeine is present in our everyday diet in the form of tea, coffee and cola drinks. It can cause an increase in heart rate and also promotes wakefulness and increases concentration.

Taurine is an amino acid which occurs in seafood and meat and so is part of our regular diet. The normal dietary intake is usually less that 200mg per day. Although naturally present in the human body, its exact function is not well established. However, it is thought to be particularly important in the healing of tissue such as occurs after surgery or significant trauma.

Glucuronolactone is a by-product of glucose. There is limited information on what foods might contain it. We do know that one of its precursors is glucuronic acid, which is part of human connective tissue.

The European Scientific Committee on Food was asked to examine the safety of high-energy drinks, which it did in a 1999 report. These were some of its conclusions:

Caffeine:

The committee found that the caffeine content of most energy drinks is 240320mg/litre. This compares with a caffeine content of coffee at 210-340mg/litre. Studies of normal individuals at rest, those taking intensive exercise and people at risk of cardiac arrhythmias showed no danger to health from normal intake of caffeine. However, there have been no studies of the effects of caffeine in combination with taurine. In children, caffeine may cause irritability, nervousness and anxiety.

Taurine:

The committee found that someone consuming 0.5 litre of energy drink per day would have a daily intake of taurine of 2,000mg. However, they concluded that there were insufficient studies to establish a safe upper-level intake. One study of athletes did show a positive effect on endurance of drinks containing taurine. The Safety Committee called for more scientific study of the amino acid.

Glucuronolactone:

The European body concluded that energy drinks contained 2,000mg to 2,400mg per litre of this. They found very limited information on the possible toxic effects. There was also insufficient information to set upper safety limits for the glucose derivative.

So what are the conclusions? Caffeine intake is not a concern for non-pregnant adults, although there has been no research on potential interactions with other products or drugs. Moderation of intake for pregnant women and children is suggested, however.

There is insufficient scientific information available to reach a conclusion on either taurine or glucuronolactone use.