Cranberries And Heart Health: What You Need to Know

  • Ciera Parsons Cardiac Physiology - University of Southampton, UK
  • Kiana Bamdad Bachelor of Medicine, Bachelor of Surgery - MBBS, Medicine, Cardiff University / Prifysgol Caerdydd

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Introduction

Cranberries are known to have vast health benefits due to their rich source of vitamins and nutrients. The most widely recognised health benefit of cranberry consumption is the prevention of Urinary Tract Infections (UTI), but what may be of less common knowledge is the benefits towards overall heart health. These benefits include reducing the risk of developing Coronary Artery Disease and heart failure through reducing blood pressure, lowering cholesterol and controlling blood sugar levels. Continue reading to learn more about the beneficial properties of cranberries. 

Nutritional profile of cranberries 

Cranberries are a rich source of certain vitamins and minerals, as well as containing high levels of fibre. Vitamins are an essential product of a healthy, balanced diet because they are necessary in facilitating many different bodily processes and functions. Fibre is also a very important substance in a healthy diet, providing the gut with “food” for “good bacteria” allowing it to grow and promote a well-balanced gut flora, protecting you from gut-related illnesses.1

Cranberries have been proven to have significant anti-oxidant and anti-inflammatory properties, which contribute to lowering one's risk of developing heart disease. 

Impact of cranberries on heart health 

Cardiovascular disease is an umbrella term used to encompass a class of diseases that involve the heart itself, as well as blood vessels throughout the body. The purpose of striving for a healthy heart is to avoid developing cardiovascular disease,  the leading cause of death globally.2 There are many preventative measures which can be taken to maximise the health of your heart, one of which is a healthy diet, involving the intake of vitamins, minerals and antioxidants. This is where the cranberries come in. 

Antioxidants 

A chemical reaction, known as oxidation, is constantly occurring throughout the body as a part of normal processes, such as cellular signalling (cells communicating with each other to achieve a function). This reaction occurs when an oxygen-containing molecule has an uneven number of electrons on its outer shell, meaning it will be actively seeking another ‘free’ electron to react with.3 This electron comes from a product known as a free radical, which also has an uneven number of electrons on its outer shell. Reactive oxygen species (ROS) are an example of a free radical and are a natural by-product of physiological processes throughout the body. However, ROS can also come from bodily exposure to harmful environments such as pollution and UV light from the sun.4

Excessive amounts of ROS in the body can cause cellular damage, which can increase the risk of developing a range of different diseases, including heart disease. Usually, cells have a defence mechanism in place to detoxify these products to prevent this damage. However, a problem arises when there is an inequality between the production of ROS and the cells’ ability to instantly detoxify reactive products. This imbalance causes something known as oxidative stress.5 

Cranberries have strong antioxidant properties which mainly come from its rich source of Vitamin C, Vitamin E and Vitamin K.6 Antioxidants pair with the free electron on the outer shell of ROS, called a free radical. This prevents the ROS from reacting with body cells thus reducing the risk of them causing cellular damage. 

Vitamin C 

Vitamins are organic compounds that everybody needs in small quantities to maintain various body functions. Vitamin C, which is also known as ascorbic acid, is essential in protecting body cells, as well as protecting cells against oxidative stress. Vitamin C also aids in the maintenance and regeneration of other antioxidants, such as Vitamin E. 

Severe Vitamin C deficiency can lead to a disease known as Scurvy, which causes bleeding, poor wound healing, hair and tooth loss and bone fragility. However, low levels have also been associated with high blood pressure and atherosclerosis (a buildup of plaque on the inside of blood vessel walls); both of which are contributors towards heart health. A study in 2003, found that a sufficient intake of Vitamin C was associated with a lower risk of coronary heart disease7, as well as finding a lower incidence of heart failure amongst participants with higher levels of Vitamin C in their blood.

Promotion of healthy blood vessels 

Additional naturally occurring compounds which are abundant in cranberries are (poly)phenols, which have been shown to provide improvement in the functioning of blood vessels (vascular function) throughout the body. The vascular system plays a significant role in regulating blood pressure, which contributes significantly to heart health. High blood pressure is often considered the most important risk factor associated with heart disease.8 A meta-analysis found that taking cranberry supplements could lead to a significant reduction in brachial systolic pressure.

In addition, flow-mediated dilation is described as the change in the diameter of a blood vessel in response to a change in blood flow, and this can be used to measure endothelial dysfunction.9 Endothelial dysfunction refers to a type of coronary artery disease in which large blood vessels constrict instead of dilate in response to changing blood flow throughout the vascular system. This can cause symptoms of chest pain, dizziness and shortness of breath during exercise and exertion. Polyphenols in cranberries have been proven to improve flow-mediated dilation in both elite athletes and coronary artery disease patients,10 suggesting significant benefits towards cardiovascular health. 

Cholesterol 

Cholesterol is a natural fatty substance in blood which is produced in the liver but is also found in some foods that we eat11. It is important in maintaining healthy cells, however, too much cholesterol in the blood can lead to health problems such as an increased risk of heart attack and stroke. Being carried around the blood in proteins, they combine to make a compound known as lipoproteins. 

You may have heard the term “good” and “bad” cholesterol. This is because there are two different types, one of which carries excess cholesterol to the liver, where it is broken down and removed from the body. This type is called high-density lipoprotein (HDL).  Non-high-density lipoprotein is the type often referred to as “bad” cholesterol. This is because a build-up of non-HDL can cause fatty deposits on the inside of blood vessels, which can lead to the narrowing of arteries and can progress to a heart attack. 

Cranberry seed oil has been proven to have great benefits in promoting low cholesterol. A study found that a dietary intake of cranberry seed oil had the potential to lower total cholesterol and increase HDL.12 

Fibre 

Fibre is a type of carbohydrate which can’t be completely digested/broken down. This means that it passes into the large intestine where it aids in a healthy digestive system and reduces constipation. 

The gut has an ecosystem of bacteria, consisting of over 100 trillion microorganisms, and makes up what is referred to as the gut microbiota. This is important because it protects the gut from harmful bacteria. Fibre is broken down by gut microbiota via fermentation which supports the growth of specialist microbes which are vital for many different mechanisms, such as control of blood sugar.13 

Regulation of blood glucose: 

Blood glucose (often referred to as blood sugar) is important because it provides cells with energy, allowing them to carry out vital processes. However, if you have excessive amounts of blood sugar it will stay in the bloodstream which can be harmful to cells. Therefore, having balanced blood glucose is very important for general health. 

As previously mentioned, cranberries are rich in polyphenols. These compounds suppress glucose release from the liver and improve uptake in peripheral tissue by encouraging cellular signalling. Therefore, less glucose remains in the bloodstream, preventing it from becoming harmful to cells.14 

Incorporating cranberries into your diet 

Cranberries can be an acquired taste due to the sharp flavour, however, there are many ways of incorporating them into your diet so that you can begin to focus on your heart health. See below for suggestions: 

  • Great on top of oatmeal or porridge for breakfast 
  • Dried cranberries as an afternoon snack 
  • Cranberry sauce pairs nicely with a range of savoury meals, such as a roast dinner 
  • A glass of cranberry juice 
  • If you don't like the taste of cranberries in any form, cranberry supplements can be a good alternative 

Considerations and precautions 

  • Like everything, cranberries should be eaten in moderation
  • Excessive consumption may lead to an upset stomach and diarrhoea 
  • Intake should be carefully considered in diabetics as it may cause a spike in blood glucose due to natural sugars 
  • High oxalate content may increase the risks of formation of some types of kidney stones15
  • If you have an allergy to aspirin, you may also be allergic to cranberries 
  • May interact with some drugs 

Potential drug interaction 

  • Warfarin, which is a blood thinner, may be affected by cranberries. They can increase the amount of time that the drug remains in the body, increasing the risk of bleeding 
  • Aspirin can be affected by the salicylic acid which is found in cranberries
  • Medications which are broken down by the liver may be affected by cranberry consumption

Other health benefits of cranberries 

Urinary tract infections 

Urinary tract infections (UTIs) are caused by bacteria in the bladder or urethra. Cranberries contain fructose and polymeric compounds which prevent bacteria, specifically E.coli from sticking to the wall of these structures.16 Therefore, this reduces the chances of infection. 

Anti-cancer properties 

The phenolic compounds found in cranberries have been found to have anti-cancer properties. This is down to a mechanism in which gene expression is influenced to decrease the growth of cancer cells and promote their self-destruction.17 

Summary 

Cranberries have many properties that can be beneficial in reducing risk factors that contribute towards overall heart health. They have the potential to lower blood pressure and cholesterol, as well as promote healthy blood vessels. They also have powerful antioxidant properties, contributing to reducing the risk of heart disease by reducing oxidative stress. As well as the many benefits provided towards heart health, cranberries also contain compounds which have been known to have anti-cancer properties and prevent UTIs. 

Whilst cranberries may be an acquired taste, there are many different ways of incorporating them into your diet, such as via cranberry juice or supplements. They’re an easy option for anyone wanting to make a small lifestyle change towards bettering their overall health!

References

  • Cronin P, Joyce SA, O’Toole PW, O’Connor EM. Dietary fibre modulates the gut microbiota. Nutrients [Internet]. 2021 May 13 [cited 2023 Dec 6];13(5):1655. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8153313/
  • Cardiovascular diseases [Internet]. [cited 2023 Dec 7]. Available from: https://www.who.int/health-topics/cardiovascular-diseases
  • Pham-Huy LA, He H, Pham-Huy C. Free radicals, antioxidants in disease and health. Int J Biomed Sci [Internet]. 2008 Jun [cited 2023 Dec 7];4(2):89–96. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614697/
  • Lodovici M, Bigagli E. Oxidative stress and air pollution exposure. J Toxicol [Internet]. 2011 [cited 2023 Dec 7];2011:487074. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3155788/
  • Pizzino G, Irrera N, Cucinotta M, Pallio G, Mannino F, Arcoraci V, et al. Oxidative stress: harms and benefits for human health. Oxid Med Cell Longev [Internet]. 2017 [cited 2023 Dec 7];2017:8416763. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5551541/
  • Nemzer BV, Al-Taher F, Yashin A, Revelsky I, Yashin Y. Cranberry: chemical composition, antioxidant activity and impact on human health: overview. Molecules [Internet]. 2022 Feb 23 [cited 2023 Dec 8];27(5):1503. Available from: https://www.mdpi.com/1420-3049/27/5/1503
  • Yan J, Tie G, Messina LM. Tetrahydrobiopterin, L-arginine and vitamin C actsynergistically to decrease oxidative stress, increase nitricoxide and improve blood flow after induction of hindlimbischemia in the rat. Mol Med. 2012 May 9;18(1):676–84. 
  • Fuchs FD, Whelton PK. High blood pressure and cardiovascular disease. Hypertension [Internet]. 2020 Feb [cited 2023 Dec 11];75(2):285–92. Available from: https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.119.14240
  • Raitakari OT, Celermajer DS. Flow-mediated dilatation. Br J Clin Pharmacol [Internet]. 2000 Nov [cited 2023 Dec 11];50(5):397–404. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2014404/
  • Labonté K, Couillard C, Motard-Bélanger A, Paradis ME, Couture P, Lamarche B. Acute effects of polyphenols from cranberries and grape seeds on endothelial function and performance in elite athletes. Sports [Internet]. 2013 Sep [cited 2023 Dec 11];1(3):55–68. Available from: https://www.mdpi.com/2075-4663/1/3/55
  • British Heart Foundation [Internet]. [cited 2023 Dec 12]. High cholesterol - symptoms, causes & levels. Available from: https://www.bhf.org.uk/informationsupport/risk-factors/high-cholesterol
  • Uw-stout [Internet]. [cited 2023 Dec 12]. Available from: http://www2.uwstout.edu/
  • Valdes AM, Walter J, Segal E, Spector TD. Role of the gut microbiota in nutrition and health. BMJ [Internet]. 2018 Jun 13 [cited 2023 Dec 12];361:k2179. Available from: https://www.bmj.com/content/361/bmj.k2179
  • Kim Y, Keogh JB, Clifton PM. Polyphenols and glycemic control. Nutrients [Internet]. 2016 Jan 5 [cited 2023 Dec 12];8(1):17. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728631/
  • Gettman MT, Ogan K, Brinkley LJ, Adams-Huet B, Pak CYC, Pearle MS. Effect of cranberry juice consumption on urinary stone risk factors. J Urol. 2005 Aug;174(2):590–4; quiz 801. 
  • Hisano M, Bruschini H, Nicodemo AC, Srougi M. Cranberries and lower urinary tract infection prevention. Clinics (Sao Paulo) [Internet]. 2012 Jun [cited 2023 Dec 12];67(6):661–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370320/
  • Cranberries: contain phenolic compounds [Internet]. American Institute for Cancer Research. [cited 2023 Dec 12]. Available from: https://www.aicr.org/cancer-prevention/food-facts/cranberries/

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Ciera Parsons

Cardiac Physiology - University of Southampton, UK

Ciera is a Cardiac Physiologist with clinical experience spanning emergency departments and clinics in both the UK and Canada. Her passion for the medical field led her to diversify into medical writing, expanding on past experiences as a writer, including producing an award-winning research project during University studies.

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