Water
Anything that places stress on the system will increase our inability to cope. Water is the most important nutrient to life itself. We can go for long periods without food but not water. Most people do not drink sufficient water.
When under stress our need for water increases yet most people top up with tea and coffee to give themselves a boost and to get them going. Tea and coffee have a diuretic effect in that they stimulate the release of water from the body making it more stressed.
We require water for brain function, to carry oxygen to the cells of the body and for almost every vital physical function. We require about two pints of water a day. Not in the form of tea, coffee, fruit juice or cola but pure water itself. A simple formula for a daily requirement is one third of an ounce of water to one pound of body weight.