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Keeping hydrated for a healthy heart

As the weather begins to warm up, now is a good time to start thinking about the ways in which we quench our thirst and the best drinks for our heart.

Woman pouring water

Getting enough fluid in each day is not only good for your brain, your mood and your digestion – it’s also essential for your heart.

What is dehydration?

Our bodies need water for digesting and absorbing food, removing waste and controlling our internal temperature.1

We become dehydrated when we don’t get enough water. Most water in our diet comes from the fluids we drink but around 20 per cent comes from the food we eat.1 Fruit, vegetables, dairy products like yoghurt and meals like soups and smoothies are all foods that contribute water to our diet.

cucumber, lime, capsicum, tomato, cherries, kiwi, apple, mandarin, watermelon. lettuce, lemon, pumpkin, strawberries

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-coloured urine, fatigue or headaches.

If dehydration is ongoing and becomes worse (moderate to severe dehydration), there is a range of symptoms you may experience, such as urinating less, weakness, feeling sleepy or muscle cramps. It is important to seek immediate advice from a health professional if you experience any of these.

How water affects your heart

Dehydration can affect many parts of our body including your heart. Your heart constantly pumps blood through your body and when you become dehydrated the amount of blood circulating through your body is reduced. To compensate, your heart beats faster, increasing your heart rate and your blood pressure.2

By keeping your body hydrated, you help your heart do its job and pump blood more effectively under less stress.2


How much fluid do we need each day?

An average-sized adult body contains around 35–45 litres of water. That means water makes up about 60 per cent of our overall body weight!

As a guide, men and women need around 8–10 cups of fluid each day (around 2–2.5 litres) which includes water and other fluids like milk and tea.1

What’s most important is listening to your own body and what it needs. We are all different shapes and sizes and have different levels of activity during the day. Some of us may work outside and be exposed to more heat and others may spend more time indoors. The fluids we need to drink each day will vary from person to person and may even vary from one day to the next.

The simplest way to stay on top of your hydration is to keep an eye on the colour of your urine. This is one of our body’s methods of balancing output with input. If your urine appears dark, then it’s a sign to drink more water until it becomes paler and clear in colour.

Some heart medications such as furosemide may cause your body to lose more water through urine and certain medical conditions such as heart failure may require restrictions to your fluid intake. Follow the advice of your doctor or specialist to help you set a goal around your own personal fluid requirements.

Water is the best way to hydrate

While all fluids can count towards your daily total to keep your body hydrated, water is the best choice.

Our 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 your daily water intake, but they both contain caffeine which acts as a diuretic and can cause you to lose more fluids. 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 too. Drinks containing alcohol are also a diuretic. If you regularly drink coffee or alcohol, it’s even more of a reason to drink plenty of water too.

energy drink -250ml 7tbs, soft drinks -  750ml 11 tsp, juice-300ml, 6.5 tsp, soft drink- 355ml 9 tsp, iced coffee - 500 ml 12tsp, iced tea - 500ml 5.5 tsp

Times when you may need more water

Your body loses water in several ways, including through sweat. You may need to drink more water than usual during the following situations:

  • On a day when you are more physically active, i.e. you may be doing more walking, gardening or housework than usual.
  • When you do structured exercise, particularly if it’s a long or intense exercise session.
  • When it is hot and humid and you are sweating more than usual.
  • On a day when you spend more time outdoors in the sun, i.e. when at the beach.
  • When you are travelling or staying away from home, as your usual habits are interrupted.
man running

Six ways to drink more water

Try these tips to keep your fluid intake up:

  1. Get into the habit of starting your day with a glass or two of water. Try to do this before you have any other food or drink in the day to get off on the right foot.
  2. If you don’t enjoy the taste of tap water, make it more appealing. Keep chilled water in the fridge, invest in a soda stream or add ice or a slice of lemon.
  3. Keep a water bottle in your car or bag so that you always have water handy.
  4. Use a reusable drink bottle that you enjoy drinking from and set yourself a goal to drink the contents and refill it a couple of times a day.
  5. Eat your water too! Fruit and vegetables can help you meet your fluid needs as well as giving your body plenty of helpful nutrients. Examples of hydrating fruits and vegetables include cucumber, tomatoes, watermelon, lettuce and strawberries.
  6. Download an App to remind you to drink more water.

Not just one thing

A heart-healthy diet and lifestyle is all about balance. Drinking plenty of water is one part of the puzzle to keep our body and heart in top condition. Eating plenty of whole foods, particularly fruit and vegetables that are close to how they are found in nature, is not only good for your heart, but it helps to keep you hydrated too.

The truth about sugar

Alcohol and the heart

Lily Henderson, NZRD

Lily Henderson, NZRD

National Nutrition Advisor

I am passionate about improving the health of all Kiwis from young through to old. I have enjoyed working in nutrition in the UK, Australia and New Zealand.


  1. Ministry of Health. Eating and Activity Guidelines for New Zealand Adults: Updated 2020. Wellington. 2020.
  2. Watso JC, Farquhar WB. Hydration Status and Cardiovascular Function. Nutrients. 2019;11(8).