Relentless drinks canIngredients
  • Carbonated water
  • Sugar
  • Citric acid
  • Taurine
  • Glucuronolactone
  • Acidity regulator E331
  • Colour, caramel E150d
  • Flavourings
  • Preservative E202
  • Caffeine
  • Inositol
  • Vitamins (niacin, pantothenic acid, B6, B12)
  • Guarana

Published May 2009

This is a high caffeine energy drink produced by Coca Cola, providing 200 Calories from sugar, and 160 milligrams of caffeine which is twice as much as a can of Red Bull and four times as much as a can of Coke or Pepsi. Caffeine stimulates the body's metabolism. The drink also supplies a few other ingredients for which there is some evidence for them boosting brain and body activity.


Citric acid provides the acid tang and the acidity regulator E331 is its sodium salt, sodium citrate, which is added to keep the acid level stable. This chemical is produced naturally by citrus fruits (hence the name) but is also made on an industrial scale by the action of a yeast on glucose solution. All kinds of household products contain citric acid such as lavatory cleaners and limescale removers.

Taurine is an acid found in testicles and named after the Latin for a bull which is taurus. It guards against oxidative stress due to over-strenuous exercise. It is sometimes given to epileptics and those with uncontrolled facial tics. Taurine is manufactured from the chemicals ethylene oxide, sodium hydrogen sulfite and ammonia.

Glucuronolactone is thought to counteract fatigue and is made by the liver from glucose and sent to the body's connective tissue and its tendons.

Colour, caramel E150d is modified caramel which is more stable than normal caramel. It is manufactured by slowly heating sugar to around 180 °C with sulfur dioxide (the gas of acid rain) and ammonia (the gas used to make artificial fertilizers).

Preservative E202 is potassium sorbate and this is added as a preservative. It occurs naturally in rowan berries.

Caffeine is the active ingredient in this drink and it both stimulates the brain by increasing the level of dopamine, relaxing the airways so making breathing easier, and it prolongs physical endurance by releasing energy from stores within the body.

Inositol is a simple carbohydrate which has a role as a messenger molecule and plays a part in the nervous system, and in the breakdown of fats to release energy. Caffeine depletes the level of inositol in the body, hence the need to add it to drinks like Relentless. Inositol comes as a white powder and it is often used to cut street drugs such as cocaine and methamphetamine (aka meth, ice, or crystal.)

Vitamins (niacin, pantothenic acid, B6 and B12) are essential dietary components which the body must have if it is to work properly.

Guarana comes from the seeds of the guarana plant which grows in Brazil and which are a rich source of caffeine.