Introduction
The food that we eat and the quantities that we consume are increasingly being studied to better understand how the nutrients that our foods contain, can have a direct effect on the way our bodies work. By understanding these processes and the types of food that are better to consume and in what quantities; we could reduce our risk of developing chronic conditions and use food sources to protect ourselves against disease. This article will review the benefits of the feijoa fruit and the potential benefits to heart health.
What is a feijoa?
Feijoas are egg-shaped green fruits that grow on evergreen shrubs/trees. These tasty aromatic fruits are native to South America; however, they are also cultivated (and very popular) in similar climate countries including Australia and New Zealand. 1 They have shiny outer skin; the inner pulp is white with tiny seeds that taste sweet like a guava with a slightly sour edge to that of a pineapple.
Types of feijoas
There are 16 varieties of feijoa worldwide. New Zealand cultivation has reached approximately 800 tons per year which are incorporated into a range of dietary products to consume. Due to the wide variety of feijoa, it is possible to grow these fruits across the seasons.1 Some of these varieties include:
- Pounamu and Anatoki in the early part of the season
- Apollo and Den’s choice in the mid-season
- Opal star and Triumph in the late season
Significance of heart health
Cardiovascular disease (CVD) is a term that groups conditions that affect the heart and blood vessels. It accounts for 38% of premature deaths globally and has been highlighted by the World Health Organization (WHO) as the leading cause of death globally. Medical conditions that would be classed under this term include coronary artery disease (disease of the blood vessels that supply the heart with blood), which could lead to acute or sudden events such as myocardial infarction (heart attack). Conditions affecting the blood vessels in the brain and the rest of the circulation are also categorized such as a stroke and peripheral arterial disease.
Several risk factors can lead to the development of CVD; some of these include an unhealthy diet, high blood pressure, and high levels of cholesterol.
So, the question is, can eating feijoas have a positive impact on overall heart health?
Packed with vitamins and minerals that can help with tissue repair, regulation of heart rhythm, and the ability to reduce some of the key risk factors in developing cardiovascular disease; feijoas are becoming of increased interest for heart protection.
Key nutrients
Per one feijoa
- Energy – 55kcal
- Carbohydrates 13g
- Protein – 0.98g
- Total Fat 0.6g
- Cholesterol 0%
- Dietary fiber – 6.4g
Vitamin C
The feijoa contains a good source of vitamin C – nearly 30% of the daily recommendation.2 The intake of adequate quantities of vitamin C is well known to contribute to improving the immune system. However, it can also play a key role in effective tissue, bone, and cartilage repair.3 This is important to the heart because it is made up of three key layers of tissue – the endocardium (inner layer), myocardium (middle layer), and pericardium (outer layer). Inside, the chambers are separated by a larger piece of tissue called the septum, and tissue valves separate the chambers.4 So, you get the picture, the heart contains lots of tissue! Adequate intake of Vitamin C could help to keep all of these tissues healthy when eaten in adequate quantities.
Recommended intake
The daily recommended intake of Vitamin C is 90 milligrams for men and 75 milligrams for women.5
Potassium
Feijoas also contains a very important nutrient - potassium. This electrolyte is vital for controlling blood pressure and the normal functioning of cells. Having the right balance of this nutrient in your body even regulates the rhythm of your heartbeat.6 Potassium is required for muscle contraction. When maintained at the correct levels, it contributes to the initiation of the heartbeat and helps the heart muscles to contract.14 When levels are too low or too high, it can cause irregular rhythms also referred to as arrhythmias.
Potassium also causes the walls of your blood vessels to relax which in turn lowers your blood pressure. The main source of potassium comes from our dietary intake. The NHS recommends that adults consume 3,500mg per day of potassium so the feijoa could contribute to this intake. There have been several studies globally that have shown links between populations that have low potassium dietary intake and higher rates of high blood pressure.6,7
More Benefits for Heart Health
Antioxidants
Within the peel and the flesh of the feijoa is a naturally occurring antioxidant called phenolic acid. These antioxidants have been well studied and found to be effective in reducing several diseases affecting the heart such as atherosclerosis and high blood pressure.8
Antioxidants work by attaching to free radicals within the body. Free radicals are molecules that have an electron spare, so they seek out other tissue or DNA to link onto. Free radicals occur as part of natural processes within the body but also can be from external sources such as pollution, smoking, and certain foods.
A harmful process within the body called oxidative stress occurs when there are more free radicals than antioxidants. The free radicals are then free to attach to other cells within the body and cause damage to those cells. Studies suggest that consumption of these antioxidants over long periods can protect against cardiovascular disease.9
Feijoas are also rich in fiber, with 17% of the recommended daily allowance in 100g of fruit.2 Dietary fibre is important for aiding digestion but also has some benefits for the heart! Several clinical studies have shown a reduction in the risk of cardiovascular disease when linked with adequate dietary fibre consumption.10 These studies have shown a reduction in cholesterol levels and in blood pressure, which as previously mentioned are key risk factors in developing cardiovascular disease.11
Another important mineral that feijoas contain is called pectin. Pectin is mostly found in different fruits and vegetables and has a gel-like consistency. When consumed, it reduces the absorption of low-density lipoproteins (LDL) also labelled as the ‘bad’ cholesterol.12 Lowering these LDLs within the bloodstream, leads to a decrease in the accumulation of deposits within the walls of the arteries, otherwise known as atherosclerosis. When cholesterol builds up within the walls of the arteries, it can increase the risk of an individual developing a heart attack or stroke. This can happen when the plaque becomes detached from the walls of the vessels and causes a blockage within the vessel. When this happens, it can lead to a heart attack or a stroke. So, keeping these levels down in the blood is important to maintain heart health.
Further to this, when pectin is processed within the bowel, it stimulates the production of short-chain fatty acids (SCFA) which play a key role in metabolism and the protection of the bowel. Several studies have linked these SCFA’s to reducing obesity, improving diabetes, and reducing inflammation within the lining of the bowel.13
Incorporating feijoa into your diet
Feijoas can be easily incorporated into a balanced diet in a variety of ways. Don’t be deceived by these unassuming small fruits, they are juicy and bursting with flavour, perfect for all kinds of recipes.
If eaten fresh, peel the skin and slice it into chunks to eat raw. These can be easily tossed into salads, pureed into yoghurts, and blended with other fruits to make smoothies. Feijoas can also be cooked, so can be made into crumbles with baked apples and processed into jams!
Smoothie recipe
Here is a smoothie recipe to get started -
- 2-3 fresh feijoas, pulped.
- 1 banana, fresh or frozen
- 1 handful of spinach leaves
- 2 chia seeds
- ½ c coconut water
- ½ c coconut milk/cream
- ½ t vanilla essence
Combine all ingredients in a blender until the desired consistency.
Start simple when incorporating feijoa into your diet. Try eating fresh and trying smoothie recipes to get started. The more you experiment with the flavour combined with other fruits and ingredients, you will get to know the combination that works for you. There are plenty of recipes out there to try.
Allergies and precautions
The fruit is generally well tolerated however, if you have any existing allergies, especially to any other foods similar to citrus fruits it is recommended to discuss with your healthcare professional before consumption. Adverse effects of consumption could be rashes, respiratory symptoms, and/or nausea. Seek help and advice from a healthcare professional if you experience any unwanted effects.
Summary
Feijoas are a unique, versatile fruit that can be easily incorporated into a well-balanced diet. They are full of nutrients that can have a positive impact on some of the key risk factors that can contribute to heart disease and have the potential to improve your current health and also protect your heart for the future. As with most foods – always enjoy in moderation!
References
- Zhu F. Chemical and biological properties of feijoa (Acca sellowiana). Trends in Food Science & Technology [Internet]. 2018 Nov [cited 2024 Jan 19];81:121–31. Available from: https://linkinghub.elsevier.com/retrieve/pii/S0924224418304606
- Phan ADT, Chaliha M, Sultanbawa Y, Netzel ME. Nutritional characteristics and antimicrobial activity of australian grown feijoa(Acca sellowiana). Foods [Internet]. 2019 Sep 1 [cited 2024 Jan 19];8(9):376. Available from: https://www.mdpi.com/2304-8158/8/9/376
- nhs.uk [Internet]. 2017 [cited 2024 Jan 19]. Vitamins and minerals - vitamin c. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-c/
- How the heart works - what the heart looks like | nhlbi, nih [Internet]. 2022 [cited 2024 Jan 19]. Available from: https://www.nhlbi.nih.gov/health/heart/anatom
- Mayo Clinic [Internet]. [cited 2024 Jan 19]. Vitamin c. Available from: https://www.mayoclinic.org/drugs-supplements-vitamin-c/art-20363932
- Sica DA, Struthers AD, Cushman WC, Wood M, Banas JS, Epstein M. Importance of potassium in cardiovascular disease. J Clin Hypertens (Greenwich) [Internet]. 2007 May 31 [cited 2024 Jan 19];4(3):198–206. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101903/
- Dyer AR, Elliott P, Shipley M. Urinary electrolyte excretion in 24 hours and blood pressure in the INTERSALT Study. II. Estimates of electrolyte-blood pressure associations corrected for regression dilution bias. The INTERSALT Cooperative Research Group. Am J Epidemiol. 1994 May 1;139(9):940–51.
- Zhang H, Tsao R. Dietary polyphenols, oxidative stress and antioxidant and anti-inflammatory effects. Current Opinion in Food Science [Internet]. 2016 Apr 1 [cited 2024 Jan 19];8:33–42. Available from: https://www.sciencedirect.com/science/article/pii/S2214799316300133
- Khan J, Deb PK, Priya S, Medina KD, Devi R, Walode SG, et al. Dietary flavonoids: cardioprotective potential with antioxidant effects and their pharmacokinetic, toxicological and therapeutic concerns. Molecules [Internet]. 2021 Jan [cited 2024 Jan 19];26(13):4021. Available from: https://www.mdpi.com/1420-3049/26/13/4021
- Threapleton DE, Greenwood DC, Evans CEL, Cleghorn CL, Nykjaer C, Woodhead C, et al. Dietary fibre intake and risk of cardiovascular disease: systematic review and meta-analysis. BMJ [Internet]. 2013 Dec 19 [cited 2024 Jan 19];347:f6879. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898422/
- McRae MP. Dietary fiber is beneficial for the prevention of cardiovascular disease: an umbrella review of meta-analyses. J Chiropr Med [Internet]. 2017 Dec [cited 2024 Jan 19];16(4):289–99. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5731843/
- Brouns F, Theuwissen E, Adam A, Bell M, Berger A, Mensink RP. Cholesterol-lowering properties of different pectin types in mildly hyper-cholesterolemic men and women. Eur J Clin Nutr. 2012 May;66(5):591–9.
- Blanco-Pérez F, Steigerwald H, Schülke S, Vieths S, Toda M, Scheurer S. The dietary fibre pectin: health benefits and potential for the treatment of allergies by modulation of gut microbiota. Curr Allergy Asthma Rep [Internet]. 2021 [cited 2024 Jan 19];21(10):43. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8433104/
- Weiss JN, Qu Z, Shivkumar K. Electrophysiology of hypokalemia and hyperkalemia. Circ: Arrhythmia and Electrophysiology [Internet]. 2017 Mar [cited 2024 Jan 19];10(3):e004667. Available from: https://www.ahajournals.org/doi/10.1161/CIRCEP.116.004667