Guidelines Dietary - Eat For Health

2.6.3 How drinking plenty of water may improve health outcomesFor oral health, water has an advantage over many commercially available drinks, including sugar-sweetened orlow-kilojoule soft drinks, ‘sports’ and ‘energy’ drinks. As well as the potentially adverse direct effects of sugar andenergy (see Section 3.3), the carbonation process creates an acidic environment that contributes to the erosion oftooth enamel. 655 Tap water also has the beneficial effects of added fluoride in many communities in Australia andfluid intake can affect saliva production and saliva, which is primarily water and essential for the maintenance oforal health. 8,36The mechanism by which coffee consumption may protect against type 2 diabetes is not clear. It has been reportedthat insulin resistance is decreased in peripheral tissues after exposure to caffeine 658 and conversely, the effect ofcaffeine on thermoregulation has been suggested as a mechanism by which glucose homeostasis is improved. 659Other components of coffee, possibly magnesium, may also assist by benefiting insulin sensitivity and reducing riskof type 2 diabetes. 660 Tea contains polyphenols known as catechins which have been reported to reduce hypertension,atherosclerosis and thrombogenesis. 661 Polyphenols also play a part in nitric oxide production from the vascularendothelium, enhancing endothelial health and reducing the risk of cardiovascular diseases and stroke. 6612.6.4 Practical considerations: drink plenty of waterAdequate fluid consumption is an integral component of a healthy diet. Water is a good source of fluids and hasthe advantage of not adding energy (kilojoules) to the diet. It is preferable to meet most fluid needs by drinkingplain water. Many commonly consumed fluids such as tea and coffee provide water, although they can haveunwanted stimulant effects in susceptible people.Guideline 2The NHMRC has developed comprehensive guidelines on tap water standards for drinking. 662 Australian tap wateris an ideal option because it is inexpensive and meets high palatability and hygiene standards. Most tap water inAustralia is fluoridated, which has been shown to be a safe and effective public health measure. Fluoridation oftap water provides an additional benefit for development of strong teeth and bones, making it a very good choiceto ensure adequate hydration. Tank water and bottled waters are a useful alternative when access to tap water islimited. Not all bottled waters contain fluoride.However, access to and availability of clean and safe water may be limited for some population groups, particularlyin remote regions of Australia. Discussion of dietary patterns and the environment is included in Appendix G.Pregnant and breastfeeding womenAs stated in the 2003 edition of the dietary guidelines, pregnant and breastfeeding women have an increasedwater requirement because of expanding extracellular fluid space and the needs of the foetus and the amnioticfluid. The fluid need is therefore 750–1,000ml a day above basic needs. 36Many authoritative bodies advise pregnant and breastfeeding women to limit their caffeine intake. For example theAustralian Department of Health and Ageing and New Zealand Ministry of Health advise that intake be restrictedto a maximum of 300 mg of caffeine per day (about three cups of coffee or six cups of tea). 428,663InfantsWater turnover is higher in infants and young children than in adults. Adequate levels of hydration are important,especially during times of potential heat stress (e.g. due to hot weather or fever). Breast milk supplies adequatewater up to around 6 months of age, but cooled boiled water may need to be provided for formula-fed infants. 351Older peopleOlder people can experience dehydration due to inadequate intake of water or other drinks. The normal declinein kidney function with age, plus hormonal changes, decreased thirst perception, medication, cognitive changes,limited mobility and increased use of diuretics and laxatives may create concern for older people. 34 These changesmay be normal adaptations of the ageing process but the outcomes of dehydration in older people are serious andinclude cognitive impairment, functional decline, falls or stroke. Particular care must be taken to ensure adequatewater intake in this group.Enjoy a wide variety of nutritious foodsNational Health and Medical Research Council63