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27 Sep 2023

Hydration for health

Food & Fluids

With warmer weather on the horizon we should be even more mindful about keeping our body hydrated. Adequate liquid intake is not only important for our brain, mood, digestion, skin, kidneys, bladder and bowel, it is essential for heart health too.

So what should we be drinking and why? The New Zealand Heart Foundation is very pumped up on hydration. With good reason.
Our bodies need water for digesting and absorbing food, removing waste and controlling our internal temperature.

In simple terms, we become dehydrated when we don’t get enough water. Most water in our diet comes from the fluids we drink but around 20% comes from food. Fruit, vegetables, dairy products like yoghurt and meals like soups and smoothies. These are all foods that contribute water to our diet.

Feeling thirsty is one way we know that we need to drink more water, but it’s also a sign your body is already slightly dehydrated. Other early signs of dehydration include a dry or sticky mouth, dark-yellow and/or smelly urine, fatigue, headaches, or feeling light headed.
If dehydration is ongoing and becomes worse (moderate to severe dehydration with symptoms such as urinating less, weakness, feeling sleepy or muscle cramps), get advice from a medical professional.

The heart of the matter
Dehydration can affect many parts of our body including the heart. The heart constantly pumps blood through the body. When dehydration occurs the amount of blood circulating through your body is reduced. The heart beats faster, increasing both the heart rate and blood pressure.

How much fluid do we need each day?
An average-sized adult body contains around 35–45 litres of water, meaning that water makes up about 60 per cent of overall body weight.

As a guide, NZ Nutrition Foundation advises women need to drink around 8 cups (2.1 litres) of fluid each day and men 10 cups (2.6 litres). This represents water or other fluids such as milk or tea. Each person is different in their tastes and absorption so ‘listening’ to the body is important. If your doctor has advised a different daily fluid intake follow your Doctors instructions.

In older age, the thirst signals decrease thus it’s important to check that you are going to the toilet regularly, and check the colour of your urine (pee): 

  • pale yellow = you are drinking enough (well hydrated)
  • dark yellow = you need to drink more (dehydrated)
  • looks like water = you are drinking too much (over hydrated).

An average-sized adult body contains around 35–45 litres of water, meaning that water makes up about 60 per cent of overall body weight. 

Nothing beats H2O
While all fluids can count towards the hydration total for the day, water is clearly the best choice. In Aotearoa New Zealand tap water is fine, you do not need to purchase bottled water; unless you doctor has advised this, or your local Council has issued a boil drinking water alert due to contamination of the water supply.

First off the body doesn’t need all the sugar found in energy drinks, soft drinks, sports drinks, juice, iced tea and flavoured milk. These drinks are high in energy (or calories) and have no or very little nutritional value.

Coffee and black tea can contribute to the daily water intake, but they both contain caffeine which acts as a diuretic (makes you pee). High consumption of either or both can cause loss of too much fluid. The amount of caffeine in black tea is usually much less than coffee (so tends to be less of an issue); and most herbal teas are either low or have very little caffeine, but they may have artificial sweeteners added which can be diuretic. Drinks containing alcohol are also a diuretic. If coffee and alcohol are on the daily drinks menu, there’s even more reason to drink more water.

Upping the intake
The body loses water several ways including through perspiration. Drinking more water might be necessary when:

  • More physically active, i.e. you may be doing more walking, gardening or housework than usual.
  • Doing structured exercise, particularly if it’s a long or intense exercise session.
  • It is hot and humid and you are sweating more than usual.
  • Spending more time outdoors in the sun.
  • Travelling or staying away from home, as your usual habits are interrupted.

Six ways to drink more water
Try these tips to keep your fluid intake up:

  1. Get into the habit of starting the day with a glass or two of water. Try to do this before having any other food or drink.
  2. If the taste of tap water doesn’t hit the spot ‘jazz’ up the liquid by keeping it chilled, adding ice, a slice of lemon or even investing in a Soda Stream type device.
  3. Keep a water bottle in the car or in your bag to keep the liquid handy.
  4. Use a reusable drink bottle that is fun, different and distinctive. Fill up and drink up the contents several times a day. This is a good way to keep track of how much water you drink per day.
  5. Fruit and vegetables help count in keeping the body hydrated. Not to mention getting more nutrients. Cucumber, tomatoes, watermelon, lettuce and strawberries are all good for hydration.
  6. If you’re computer savvy download an App to remind you to drink more water such as WaterReminder available on Google.

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Date Published: September 2023

To be reviewed: September 2026