Hydration and Heart Health: Why Staying Hydrated Matters

Helena Davies
Jun 27
3 min read

As temperatures rise it’s essential to prioritise hydration—especially since our bodies are made up of around 50 - 70% water. Water is essential for life. It plays a key role in regulating body temperature, supporting digestion, removing waste via urine and even helping to keep our joints lubricated and moving smoothly.

Why Hydration Is So Important for Your Heart

When we don’t drink enough fluids, dehydration can cause extra strain on the heart. Here’s why hydration is particularly important for heart health:

Dehydration can lower blood pressure, trigger palpitations or tachycardia (a fast heartbeat) and even increase the risk of blood clots.
Hydration supports alertness and concentration, which can dip if we don’t drink enough.
It helps prevent constipation and supports healthy digestion.
During episodes of vomiting or diarrhoea, your body loses fluids more quickly—so it’s extra important to rehydrate during these times.

Important: If you have been advised by your doctor to follow a fluid restriction (for example, if you have heart failure or kidney disease), always follow your medical team’s advice and speak to a healthcare professional before making changes to your fluid intake.

How Much Should You Drink?

The general recommendation is to aim for:

6-8 glasses (about 1.6–2 litres) of fluid per day, whether you’re exercising or not.

Symptoms of Dehydration

Watch out for signs that you may not be drinking enough:

Feeling dizzy or lightheaded
Feeling tired or weak
Headaches
Dry or sticky mouth
Sunken eyes
Passing urine less often

Seek immediate medical attention if you experience:

Confusion or drowsiness
Severe dizziness or fainting
Not passing urine for more than 8 hours
A weak or rapid pulse

Top Tips for Staying Hydrated

Aim for 6-8 cups per day.
Choose low-calorie, sugar-free options like water, sugar-free drinks, tea or coffee.
Set regular reminders to have a drink throughout the day.
Always carry a water bottle, especially in hot weather.
Make your drinks more appealing: add ice, no-added-sugar squash or fruit slices to your water.
Include hydrating foods like watermelon, cucumber, and tomatoes.
Sip fluids little and often—this can help you stay on top of hydration without feeling overwhelmed.
Hydration is especially important if you’re feeling unwell.
Limit fruit juice to 150ml per day due to its natural sugar content.

Hydration and Exercise

If you are drinking regularly throughout the day (around 6-8 cups), you’re likely starting your exercise session well hydrated.
For most people doing cardiac rehabilitation (CR) or general exercise, water is the best option for hydration.
Always remember to replenish fluids after exercising.

Special Considerations: Fluid Restrictions

Some people with heart conditions, particularly heart failure, may be advised to limit their fluid intake to prevent fluid overload. It’s essential to continue following this advice even in hot weather or when exercising.

If you’re feeling symptoms of dehydration but are on a fluid restriction, speak to your GP or specialist cardiac nurse—they can help adjust your plan if necessary.

Top tip: If you are following a fluid restriction chewing gum or using mouth sprays can help stimulate saliva and reduce the sensation of a dry mouth.

Hydration Myth: Does Tea and Coffee Dehydrate You?

Myth Busted: Tea and coffee do not dehydrate you. In moderate amounts (around 4-5 cups per day), they actually contribute to your overall fluid intake. The water content outweighs the mild diuretic effect of caffeine.

Want to Learn More?

If you’d like personalised advice or further information on heart health and hydration, feel free to get in touch. You can email me at dietitian.davies@gmail.com to enquire about consultations and tailored support. I’d love to help you on your journey to better health!

References

This blog post was written by Helena Davies, Clinical Dietetic Specialist, with AI assistance