We all know it: eating fruits and vegetables is good for our health. But how much is enough, exactly? The World Health Organisation (WHO) says, to help lower the risk of serious health conditions such as heart disease, stroke, type 2 diabetes and several types of cancer, we should eat at least 400g a day (for context, your typical apple weighs 150g).
How well we meet this goal varies around the world. But across the 38 countries in The Organisation for Economic Co-operation and Development (that includes the US and UK), only 15 per cent of people eat the recommended amount.
That's worrying because, as you'd expect, fruit and veg contain a smorgasbord of nutrients that keep our brains and bodies in tip-top shape. However, it could be that one class of nutrients, known as polyphenols – the biggest nutritional buzzword of 2025 – is of particular value.
The hidden reasons fruits and vegetables are vital for our health
When we talk about the health benefits of fruits and vegetables, we often focus on the fact that they are nutrient-dense whole foods. This means that they are packed with vitamins and minerals – essential in supporting normal functions in our bodies – without being high in calories, fats, salt, or sugar.
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We could, theoretically, get all the vitamins and minerals we need without eating many, if any, fruits or vegetables. And although the same could be possibly said for eating supplements and meal replacement products, they aren’t natural whole foods. This means they are missing one important element that gives us huge health benefits: phytonutrients.
Phytonutrients are natural compounds found in plants that give them their colours and flavours and help protect them from environmental stress, pests and disease. They also play a key role in promoting human health.
There are thousands of different phytonutrients which can be grouped into major classes based on their chemical structures. These include carotenoids (which give fruits and vegetables their red, orange and yellow colours) and glucosinolates (found in cruciferous vegetables such as broccoli and cabbage).
However, the most abundant and well-researched class of phytonutrients are polyphenols. More than 8,000 of these unique compounds have been identified in plants. Foods such as olives, plums, hazelnuts and tea all contain high levels of polyphenols.
How polyphenols change your body
Polyphenols are named for their chemical structure: 'poly' means many, and 'phenols' indicate they contain phenolic groups. These are ring-like structures composed of carbon, hydrogen, and oxygen atoms.
It's these unique structures that play a crucial role in the biological reasons behind polyphenols' health benefits, including their antioxidant, antimicrobial, and anti-inflammatory effects.
Antioxidant polyphenols protect the body from damage caused by free radicals and reactive oxygen species (ROS) – molecules produced during metabolism and stress responses. They can also form due to environmental factors like pollution, sunlight, and toxins such as cigarette smoke.
Free radicals and ROS can cause damage to your cells, proteins, and DNA. They can contribute to the ageing process and the development of heart disease, cancer, and neurodegenerative disorders like Alzheimer's and Parkinson's. Fortunately, polyphenols have been shown to neutralise these.
Inflammation can play a key role in healing wounds and clearing infection, but uncontrolled, chronic inflammation can increase the risk of health issues such as arthritis and cardiovascular disease. Polyphenols can also help with this by inhibiting the enzymes involved.
Polyphenols can also protect against harmful bacteria, viruses, and fungi, which can trigger inflammation and disease if allowed to go unchecked. They achieve this by interacting with cell membranes, disrupting their structure and function, and ultimately stopping their growth or destroying them altogether.
If that wasn't enough, polyphenols also interact with enzymes in the body to support digestion and metabolism. For instance, they can block enzymes that break down certain beneficial nutrients or activate those that boost detoxification.
This is all before we come to how polyphenols impact what's known as 'gene expression'.
Genes, as you'll probably know, are segments of DNA that carry the instructions for building everything in the body. They serve as the blueprint for creating proteins, essential molecules that perform a wide variety of functions throughout the body including the building and repair of muscles and bones and the production of hormones and enzymes.
Each gene contains instructions for making specific proteins, but they don't always give the green light for your body to do so. Genes can be turned on or off depending on the situation – they get flipped based on what the body needs at any given moment.
Some polyphenols can influence this process, helping to increase the production of protective proteins or decreasing the production of harmful molecules.
Finally, polyphenols can also have a ‘prebiotic-like’ effect on the microbes in the gut. This means that they can promote the growth of beneficial bacterial families such as Bifidobacteriaceae and Lactobacillaceae, which help to protect us from infection, and reduce the number of harmful bacteria.
How to get the most polyphenols
The good news is that all fruits and vegetables contain polyphenols. There isn't just one specific polyphenol superfood. In fact, it’s better to eat a variety of colourful fruits and vegetables in your diet – the different colours often indicate foods containing different types of polyphenols.
Eating a variety of polyphenols is important because the different types have unique structures and provide different specific health benefits. This means several polyphenols can act with each other to enhance their impact. So, eating as diverse a range as possible will help to maximise their potential advantages for your overall health.
Extracts and supplements can be a useful way to make valuable products from the wasted parts of fruits and vegetables. However, taking polyphenols in very concentrated amounts may have counter-intuitive impacts, including acting in a way that damages the body in some cases.
Also, don’t forget that fruits and vegetables come as a complete package, so the benefits of eating them can never be replaced with a supplement containing just one component of their health-giving goodness.
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