Antioxidant Powerhouse: Feijoa's Cellular Protection

What is Feijoa?

Feijoa (Acca sellowiana) is a fruit belonging to the myrtle family, native to the highlands of southern Brazil, eastern Paraguay, Uruguay, and northern Argentina. Its sweet and aromatic flavours make it delicious for consumption whilst being packed full of nutrients and antioxidants which exhibit many health benefits.

One serving of feijoa provides a great source of dietary fibre and immune-boosting vitamin C whilst remaining at a low glycaemic index. Feijoa is a popular fruit in South America and New Zealand where the climate conditions favour its growth but it is now starting to become more recognised in other parts of the world due to its delicious flavours and myriad of health benefits. 

This article explores the cellular protection properties that feijoa provides by being packed full of antioxidants, offering many powerful health benefits. 

What are free radicals and antioxidants? 

Antioxidants are vital to the body to maintain cellular health to deal with both internal and external environmental stresses. During normal metabolic reactions and other exogenous processes such as UV radiation and smoking, molecules called free radicals are produced. These free radicals are extremely unstable and reactive within our cells due to the fact they have one unpaired electron in their outer shell.

Within our cells, biomolecules such as DNA are particularly susceptible to attack by free radical molecules. Free radical attack on the DNA double helix structure results in oxidative damage which can lead to mutagenesis. The introduction of mutations within the DNA can lead to an increased risk of cancer development and other degenerative diseases such as rheumatoid arthritis and cardiovascular diseases.

Luckily, our bodies are capable of many DNA repair mechanisms which can recognise these free-radical damaged sites on DNA and prevent the development of cancers. These processes are greatly reliant on antioxidant molecules within our cells which donate an electron to the free radicals reducing their reactivity and neutralising their instability within the cell.

Antioxidants can be acquired naturally through endogenous sources such as alpha lipoic acid and glutathione, and an exogenous supply such as from fruits and vegetables containing vitamin C, vitamin E and beta-carotene. Additionally, phytochemicals which are packed into all plants exhibit further antioxidant properties suggesting that all plant sources are of great help to maintenance of cellular protection and health.¹ 

Feijoa: an antioxidant powerhouse

A 100g serving of fresh feijoa is packed full of vitamin C, providing us with 32.9mg - 82% of our daily recommended intake according to the NHS.^2,3 As previously mentioned, vitamin C from our diet provides an exogenous supply of antioxidants whilst boosting immunity by stimulating the activity of white blood cells.

Vitamin C antioxidant mechanism of action 

Vitamin C is a potent reducing agent capable of neutralising the unstable effects of free radicals by donating an electron to the damaging molecules within our cells. Vitamin C’s hydrophilic properties allow it to work both inside and outside the cell to neutralise free radicals. Not only can vitamin C reduce free radicals and prevent oxidative damage themselves, but it can also regenerate other antioxidants in the body such as vitamin E.

Like vitamin C, when vitamin E exerts its antioxidant powers it becomes oxidised. To continue its protective role of neutralising free radicals in the cell it must be reduced again which creates a vitamin E recycling mechanism.⁴ Vitamin C can restore vitamin E to its reduced state - further demonstrating it as another powerful anti-oxidising tool within the cell.

Our bodies cannot produce vitamin C on their own so getting complete supplies from sources from our diet such as feijoa is important to maintain cellular protection. The antioxidant activity of feijoa fruit extracts has been investigated by A. Smeriglio et al. using an antioxidant and free radical scavenging activity assay on human red blood cells.⁵

Their research shows that feijoa extracts not only exhibit strong antioxidant activity but also prevent oxidative damage mediated by free radicals in a dose-dependent manner. This suggests that consuming a greater quantity of feijoa boosts antioxidant activity and cellular protection demonstrating it to show great health-boosting benefits.⁵ 

Not only does a deficiency in vitamin C reduce the antioxidation of free radicals, but it also leads to several other health defects. Adults aged 19-64 require 40 mg of vitamin C a day which is easily obtainable through dietary sources without the need for supplementation. Furthermore, since vitamin C cannot be stored in the body a sufficient supply must be consumed each day.¹⁰

Vitamin C deficiency effects:

• Weakness and fatigue
• Bleeding under the skin and gums
• Anaemia 
• Prone to infections 
• A severe deficiency can cause scurvy 

In the case of vitamin C overconsumption through the use of supplements, some negative effects can occur. 

Overconsumption (>2000mg) of vitamin C effects:

• Diarrhoea
• Nausea
• Vomiting 
• Stomach cramps 

Luckily, since fresh fruits and vegetables such as feijoa are packed full of vitamin C, a deficiency can be easily overcome without the need for further medical intervention. 

FAQs

Is it possible to grow feijoa in the UK?

Yes, it is possible to grow feijoa in the UK, particularly in more temperate regions with mild climates. However, due to the cooler weather, it may require specific care and consideration. Feijoa trees can tolerate temperatures down to around -9°C (15°F), but they benefit from a sheltered, sunny spot, well-draining soil, and potential winter protection against frost when young.

While the fruits might not achieve the same sweetness or size as in their native climates, with proper attention, including site selection and potential winter safeguards, feijoa trees can still be cultivated and produce enjoyable fruits in the UK.

How many feijoas should you eat in a day?

Feijoas are nutritious and low in calories, rich in vitamin C, fibre, and antioxidants. Consuming a few feijoas a day as part of a balanced diet is generally considered healthy. However, eating excessively large quantities may cause digestive discomfort due to their fibre content. 

What other fruits have high antioxidant content? 

Some of the fruits with the highest levels of antioxidants include berries like blueberries, strawberries, raspberries, and blackberries. Other fruits rich in antioxidants include pomegranates, cherries, cranberries, and oranges. These fruits are abundant in compounds like vitamin C, flavonoids, anthocyanins, and other polyphenols, which contribute to their potent antioxidant properties. Regular consumption of these fruits as part of a balanced diet can offer various health benefits, including reducing oxidative stress and supporting overall well-being.

Summary 

The damaging effects of free radicals are largely unavoidable in the world we live in today due to factors such as pollution, UV damage and smoking but the consumption of antioxidant-rich foods, such as feijoa, is one of the best ways to boost our body's ability to deal with these damaging agents.

Feijoa’s high vitamin C content makes it a powerhouse full of antioxidants that help protect our DNA from damage and maintain the normal metabolic processes in our cells. Whilst feijoa is not currently a popular fruit for consumption in the UK, hopefully, we will see a rise in its popularity due to the strong cellular protection and health-boosting benefits it provides.