Introduction

Your cardiovascular system, which consists of your heart and blood vessels, is essential to you. The heart, which beats roughly 2.5 billion times over an average lifespan, pumps blood full of oxygen, important nutrients and a variety of crucial cells into blood vessels called arteries. These arteries then carry this rich blood to every part of the body, to give your every other organ system the energy and resources it needs to function properly. Another type of blood vessels, called veins, instead take away any waste product from organs all over the body, and bring it back to the heart, where the organ will then pump this blood to the lungs for the waste products to be expelled out of the body.¹ When the cardiovascular system stops working, so does the rest of the body, as it does not have the proper nutrients to function effectively. Hence, keeping your cardiovascular system healthy is vital. Not only does a healthy cardiovascular system help keep the rest of your organ systems functioning properly, it also greatly reduces your chances of developing any type of cardiovascular disease (CVD), which is the leading cause of death worldwide. 

The fruit kiwi, also known as Chinese gooseberry, is an edible fruit from a type of plant known as woody vines (Actinidia). Native to China and Taiwan, this fruit (which is most commonly found in golden and green variations) is now grown all around the world, due to its rising demand. One of the reasons as to why the kiwi fruit is becoming more and more popular is due to its significant health benefits. Kiwis are considered one of the healthiest fruits you can consume - part of this is due to its benefits to your cardiovascular system.² This article will outline how the rich nutritional components of the kiwi benefit your cardiovascular health.

Nutritional composition of the kiwi 

Although the kiwi is a relatively small fruit in size, it is full of rich, essential nutrients. 

Kiwis are packed with the following vitamins and minerals:³

• Vitamin A
• Vitamin B9 (also known as folate)
• Vitamin C - Kiwis are exceptionally high in this vitamin (particularly the golden kiwi variation). In fact, one kiwi provides more vitamin C than two oranges
• Vitamin E
• Vitamin K
• Potassium
• Copper
• Magnesium 

Kiwis are also packed with dietary fibre - in fact, if you consume 2 green kiwis per day, they would provide you with approximately ¼ of your daily recommended intake of dietary fibre (6g of fibre).³ 

The kiwi is also an excellent source of phytochemical compounds, which are chemical substances that plants produce, and such compounds help fight any infections that could hinder their growth and the growth of their fruit. These substances remain in the fruit as well as the plant, and can be very beneficial to your cardiovascular health. Examples of these phytochemical compounds include polyphenols, flavonoids and carotenoids.³ 

How do kiwis help keep your cardiovascular system healthy? 

The rich nutrient profile of kiwis help keep your cardiovascular system healthy in a variety of different ways. The most prominent mechanisms are detailed below.  

Minerals’ contribution to regulating blood pressure

Your blood pressure is the pressure of blood pushing against the walls of your arteries. If this pressure is too high, this is known as hypertension, and this can affect your arteries’ function of carrying nutrient-rich blood around the body. In turn, hypertension can also increase your chances of developing a CVD.⁴ The minerals in kiwis help reduce your chances of having hypertension, and instead keep your blood pressure at healthy levels:

• Magnesium - Magnesium helps significantly lower the risk of developing hypertension by releasing a hormone-like compound called prostacyclin, which can reduce tension in your blood vessel walls^5,6    
• Potassium - Potassium can significantly decrease your blood pressure by aiding in the relaxation of the walls of the blood vessels, and protecting the walls from ‘cramping up’⁷

Impact of vitamins on the cardiovascular system

The wide array of vitamins found in the kiwi all work together to keep your heart and blood vessels healthy:

• Vitamin C - Vitamin C is essential for the endothelium, which is the inner surface of your blood vessels. This layer of your vessels has various important functions, including the regulation of all exchanges that take place between the bloodstream and organs (such as exchange of oxygen and waste products), as well as the regulation of the size of blood vessels.⁸ If the endothelium does not function properly, then this can lead to hypertension, atherosclerosis (the build-up of fats in your blood vessels, causing blockages) and CVD formation.⁹ Hence, vitamin C helps keep your endothelium and in turn blood vessels healthy and functioning properly. Moreover, vitamin C has shown to significantly reduce your risk of dying from a CVD¹⁰ 
• Vitamin B9 (folate) - Folate has shown to significantly lower your risk of developing a CVD. This is likely due to the fact that folate can break down an amino acid (chemical ‘building blocks’ of proteins) called homocysteine. Elevated levels of this amino acid is actually a known risk factor for developing a heart disease, and hence folate can help reduce such a risk by eliminating these high levels of homocysteine¹¹ 
• Vitamin E - Vitamin E prevents the formation of dangerous blood clots in your blood vessels. Blood clots are gel-like blood masses that form in your blood vessels which help control bleeding. However, they can also cause serious cardiovascular issues, such as heart attacks, if they get too big or if they obstruct an important part of your cardiovascular system. Hence, vitamin E helps in the prevention of cardiovascular problems¹² 
• Vitamin K - Vitamin K is known to regulate calcium in your cardiovascular system. Calcium is a mineral which helps blood clot normally, as well as helps the heart beat normally by aiding the organ’s muscles and nerves to function properly. Vitamin K helps direct the calcium where it needs to go to help your heart and blood vessels function. In addition, vitamin K helps avoid atherosclerosis development¹³ 

Antioxidants and their benefits for cardiovascular function

There are various nutrients in the kiwi that are known to be substances called antioxidants. Antioxidants are substances which protect your cells from compounds known as reactive oxygen species (ROS). ROS are naturally-occurring, highly reactive compounds which are produced in your body either during various cellular reactions or via exposure to toxins such as radiation, pollution, and cigarette smoke.¹⁴ Moderated levels of ROS play important roles in a variety of bodily processes. However, elevated levels of ROS in your body can lead to DNA damage (damage of our genetic material found within cells, causing the cells to not function properly and die). This process is known as oxidative stress, and this process can damage our cardiovascular system by increasing your risk of developing hypertension, atherosclerosis, arrhythmia (irregularities in your heartbeat) or a CVD.¹⁵ 

The antioxidants in kiwis help counter this oxidative stress, by interacting with excess ROS and preventing them from affecting your cardiovascular system too much. This in turn can lower your risk of developing any of the conditions mentioned above, helping to keep your cardiovascular system as healthy as possible. Specific examples of antioxidants found in the kiwi include its  phytochemical compounds, potassium, copper, and the vitamins  A, B9, C, E and K.¹⁶  

Dietary fibre and its role in heart health

The dietary fibre found in kiwis can help keep your heart and blood vessels healthy as it helps reduce and regulate your blood pressure. It also helps prevent inflammation around the heart, which if left unregulated can damage the heart and stop it from functioning properly. A further way dietary fibre helps your cardiovascular system is that it leads to a decrease in a type of fat found in your body called low-density lipoprotein (LDL) cholesterol, which is the fat that typically leads to the formation of atherosclerosis in your blood vessels. 

Hence, through its regulation of blood pressure and inflammation, as well as its prevention of LDL cholesterol build-up in your blood vessels, dietary fibre overall helps reduce your chances of developing and suffering from a CVD.¹⁷

FAQs

What is the daily recommended intake of kiwi?

Having kiwi as one of your 5-a-day fruit and vegetable portions is highly recommended. One 5-a-day portion equals 2 kiwis. It is important to not only eat kiwis for your daily fruit and vegetable portions - it is crucial to have a balanced diet, as too much of any food can in turn cause adverse effects. 

What are the best ways to eat kiwi?

Most people prefer to consume kiwis fresh. You can also add kiwis to smoothies, in fruit salads, and you can also pair it with yoghurt. 

Do kiwis cause any adverse reactions?

Although generally safe, kiwis can sometimes cause some adverse effects. Some people can be allergic or have an intolerance to kiwis or substances within them, and this can cause allergic reactions, from mild to severe. Examples include:

• Itchy mouth
• Rashes
• Stomach pains
• Breathing difficulties
• Vomiting 
• Dysphagia - trouble swallowing

Moreover, as certain kiwi substances prevent blood clots, consuming kiwi along with slow blood clotting medications can sometimes lead to certain issues. Too little clotting of the blood can in turn lead to more bleeding or bruising. Hence, if you are on medication specific for blood clotting, you must be cautious about consuming kiwi. The same applies to people who have a bleeding disorder. 

As kiwis are known to help decrease your blood pressure, if you are on any medications to decrease high blood pressure already, then consuming kiwis alongside such medication can sometimes cause your blood pressure to drop too low, in turn causing adverse effects. Hence, it is also important to be cautious when consuming kiwi if you are on high blood pressure medication. 

Summary

Kiwis are known as one of the healthiest fruits to consume - and for good reason. The kiwi’s rich nutritional composition of vitamins, minerals, dietary fibre and phytochemical compounds all help in keeping your cardiovascular system healthy, and help prevent the development of CVDs. The nutrients do so through a variety of mechanisms - including lowering high blood pressure and cholesterol levels, regulating the clotting of your blood, and through their antioxidant components. Hence, adding kiwis to your daily fruit and vegetable portions is definitely recommended. However it is important to not limit yourself to just kiwis - having a variety of fruits and vegetables daily is very important for your cardiovascular health.