16 Can I drink too much?Hyponatremia is when there isn’t enough sodium com-pared to the water content in the blood. Sodium is es-sential for many essential bodily functions including nervous impulses, maintenance of fluid balance and maintenance of blood pressure. Hyponatremia is usu-ally caused by excessive consumption of water without correcting electrolyte loss, often after endurance or strenuous exercise. A study published in the American Journal of Physiology (2002) and a further study in the Journal of the American Society of Nephrology (2008) demonstrated no significant health benefits of drinking the recommended eight glasses of water daily. However, the kidneys do an excellent job of filtering and secreting excess water from the body, so surely it’s better to keep our organs and internal environment well watered for optimum health and performance, rather than accept sub-optimum existence or run the risk of ill health? Best options for hydration – hypotonic, isotonic or hypertonic? Hypotonic drinks contain a lower level of solutes (sug-ars, mineral salts) than human blood. These types of drinks, such as water, are best for general on-going re-hydration. Isotonic drinks contain 4-8% of solutes in solution, the same concentration as in blood (hence the prefix of iso-). The isotonic solution can enhance ab-sorption across the intestinal and capillary membranes into the bloodstream, re-hydrating and replenishing mineral salts and sugars more quickly. Although not necessary for the average exerciser, these drinks can be useful after prolonged or very strenuous activity. Hypertonic drinks are those that contain more than 8% solutes, and include most carton fruit juices, which are usually 10% sugar, fizzy drinks and sports gels. These require digestion and are best for replenishing carbohy-drates after sport or activity, rather than for rehydration purposes. However, you can use juices to make your own isotonic drink – just mix 50% fruit juice (contain-ing 10g per 100ml sugar content) with 50% water, and you have diluted the sugar content down to 5%, creat-ing your own isotonic drink. unIted KIngdom Hyponatremia is usually caused by excessive consumption of water without correcting electrolyte loss, often after endurance or strenuous exercise. Water Already contains electrolytes such as sodium, potassium, magnesium, calcium and chloride. Freshly ‘blitzed’ fruit or vegetables in a blender Better than juicing as you still get the fibre in a blended fruit or vegetable. This option requires digestion, so is not absorbed as quickly plain or isotonic but contain of vitamins, minerals (including electrolytes), phytonutrients (e.g. carotene, lutein, lycopene) and sugars for energy. Choose fruits vegetables specific properties and/or glycaemic index (GI) values. A higher GI value will sugars the oodstream carbohydrate stores more quickly. Watermelon has a high GI meaning its sugars are predominantly glucose wilreplenish quickly. water will also replenish fluid levels.