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Can I drink coffee and have a healthy heart?

Coffee is the biggest source of caffeine worldwide and Kiwis love their coffee. This week we're looking at how much caffeine we should have and how it affects our heart health.

Two holds holding coffee cups

What is caffeine?

Caffeine is a naturally occurring substance that belongs to a group of compounds called methylxanthines.

It is found in over 60 plants worldwide, including the humble coffee bean and the berries of the guarana plant. It's believed that the caffeine in these plants helps to protect them from insect damage. For us humans, it acts as a stimulant and is the most commonly consumed psychoactive substance in the world.

Where is caffeine commonly found?

There are several common food and drinks that naturally contain caffeine such as: coffee, tea (both black and green tea) and chocolate. Caffeine can also be added to drinks, such as energy drinks and soft drinks. Both tea and coffee are the most popular beverages worldwide, with coffee being by far the biggest source of caffeine consumption.

How does caffeine affect your body and especially your heart?

The first benefit that comes to mind when thinking about coffee is that it helps when we’re tired. Coffee and other drinks containing caffeine increase the activity in our brain which helps to increase alertness, reduce tiredness and increase concentration.

This can be a driver for many getting their morning coffee fix. However, there can be potentially negative side-effects for some as caffeine affects everyone in different ways and some people can be more sensitive to caffeine than others. 

Some downsides can include feeling jittery, irritable or anxious, an increased heart rate and/or heart palpitations and sleep problems. 

Research over the years has resulted in inconsistent messaging about whether we can continue our daily coffee fix. Most studies find no association between heart disease and coffee intake. Some also see a small benefit when looking at moderate coffee consumption. 

It’s important to remember that in plant sources of caffeine, and especially in coffee, there are a vast range of other compounds and nutrients, such as antioxidants, that can also have a positive influence on our heart health. Therefore, it is difficult for researchers to single out one component of the coffee bean, the caffeine, to look at the effect it has on humans.

Does caffeine affect your blood pressure?

Many effects of caffeine, both positive and negative, can be temporary and reversible. For example, some people experience an increase in blood pressure, but this may only last for around four hours. This is therefore reversible, however the long-term impact on overall blood pressure from this temporary effect has not been well researched and remains uncertain.

How much caffeine is too much?

In New Zealand, there are no firm guidelines on how much caffeine is too much for the general population. For children and pregnant or breastfeeding women there are strict caffeine guidelines. For children it’s recommended to have no more than 3mg of caffeine per kg of bodyweight. For pregnant and breastfeeding women, it’s recommended they limit caffeine to 200mg or less a day from all sources.

Although there is a lack of guidelines, there is a recommended maximum daily caffeine intake.

For adults who are not pregnant or breastfeeding this equates to a maximum of 400mg of caffeine per day and no more than 200mg in one sitting. As food and drink sources of caffeine can vary, so does the caffeine content. Depending on the product and size, 400mg can add up quickly.
For example, a cup of coffee tends to have more caffeine than a cup of tea, but this also varies between the type of beans and how they are prepared.

  • Caffeine in brewed coffee can range between 95–200mg per cup.
  • Instant coffee can range from 27–173mg per cup.
  • Black tea contains between 40–120mg per cup.
  • Green tea between 25-29mg per cup.

For tea, the amount of caffeine depends on how much water it is brewed in, how long it’s brewed for and the quality of the tea.

Examples of 400mg of caffeine in drinks. 8 cups of tea (50mg caffeine per 220ml cup) 14 cups green tea (27mg caffeine per 250ml cup) 2.5 cups instant coffee (80mg per 250ml cup) + 2 cups tea (50mg caffeine per 220ml cup) 2 espressp, 1 energy drink & 1cola

What about pure and highly concentrated caffeine products?

Caffeine powder is referred to as 'pure caffeine' and is sometimes found in products sold online or in health food stores.

These products can contain thousands of serves of caffeine in a packet. This makes it very difficult for the consumer to measure out what would be a maximum dose (around 1/16th of a teaspoon). One small teaspoon can be equivalent to 25–50 cups of coffee which can be lethal.

Another example of this is green tea extract (GTE) which can be found in supplements or other health food products claiming to be good for your health. GTE has resulted in liver damage and can also be lethal.

In December 2019 Food Standards Australia New Zealand (FSANZ) updated their regulations which prohibit the retail sale of pure caffeine and highly concentrated caffeine products of certain levels (caffeine concentration of 5% or more if the food is a solid or semi-solid food or 1% or more if the food is a liquid food). 

Moderating caffeine intake

Sometimes our caffeine consumption from food and drinks can creep up over time. Moderating the amount of caffeine, you have a day can help keep you feeling at your best and prevent any unwanted side-effects.

Here are some simple swaps to your hot and/or cold drinks to reduce the amount of caffeine you have each day.

  • Swap to decaf coffee and decaf black tea.
  • Swap to naturally caffeine-free herbal tea such as peppermint, camomile, berry or lemon & ginger.
  • Swap soft drink/energy drink for plain or sparkling water with cucumber and mint for flavouring.

Coffee maker

What does the Heart Foundation recommend?

When it comes to our energy levels and overall health, caffeine cannot replace the combination of a well-balanced heart-healthy diet, exercise and sleep.

A moderate amount of caffeine should be fine for most healthy people to consume. Keep in mind the recommended limit of 400mg per day to avoid any negative side-effects. It is important to remember we are all different and some of us are more sensitive to caffeine than others. These sensitivities can result in several negative symptoms mentioned above which can be unpleasant or unsettling. 

If you find yourself experiencing these symptoms, take a note of how much caffeine you have consumed and aim to reduce this gradually until you reach a point where you are no longer experiencing these adverse effects. Some people prefer to remove caffeine entirely and that is completely OK as well. 

Do keep in mind the timing of your last caffeine intake. Caffeine can still be in our system around six hours after our last cup. Good quality sleep is important for maintaining health and preventing disease. Be mindful of whether a late afternoon or evening coffee is keeping you up later than planned or preventing a restorative sleep that the body needs every night.  

The risk from pure and highly concentrated caffeine products is clear, and the Heart Foundation recommends avoiding all types of products that contain this type of caffeine.

Read more nutrition facts

Nickie Hursthouse, NZRD

Nickie Hursthouse, NZRD

National Nutrition Advisor

As a Registered Dietitian, I know that food gives us so much more than just nutrients. I am driven to simplify nutrition messages, educate on all aspects of food and support Kiwis to develop a love of food that helps them stay healthy throughout their life.