Polyphenols are a group of natural compounds found in plants, characterised by their antioxidant properties. These bioactive substances contribute to the vibrant colours, bitterness and odour in fruits, vegetables, tea, coffee, and other plant-based foods.
Polyphenols play a key role in promoting health by neutralising harmful free radicals and have been shown to have anti-inflammatory properties. There is a large body of research that suggests long term consumption of plant polyphenols offer protection against development of cancers, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. Polyphenols may act as prebiotics, promoting the growth of beneficial gut bacteria and contributing to overall digestive health.
What are Polyphenols?
Polyphenols are distinguished by the existence of multiple phenol structural units in their chemistry. In nature these compounds play a pivotal role by aiding the plant's defence mechanisms against environmental stressors, pathogens, and UV radiation. Due to their potential health benefits, polyphenols are significant components in the human diet. Polyphenols are split into several groups according to their chemical structures.
Flavonoids
This is the largest and most studied group of polyphenols. They possess a number of beneficial properties such as anticancer, antioxidant, anti-inflammatory, and antiviral. Foods high in flavonoids: green and black tea, berries, citrus fruits, apples, pears, onions, broccoli and tomatoes.
Lignans
Lignans are phytoestrogens, which means they have weak oestrogen-like effects. The human body is unable to synthesise its own lignans and therefore can only be obtained through food. They are anti-inflammatory, antioxidant and possess antitumor activities. Research shows that can also decrease the risk of cardiovascular disease. Foods high in lignans: flaxseeds, chia seeds, sesame seeds, barley, oats, chickpeas, lentils, broccoli, Brussel sprouts and kale.
Stilbenes
Stilbenes are part of the plant's defence mechanism. They are produced in response to stressors such as infection, UV radiation, and injury. Stilbenes are an antioxidant and help to neutralise free radicals potentially reducing oxidative stress in the body. Research shows that stilbenes may have potential benefits in cardiovascular health, anti-aging, and certain health conditions. Foods high in stilbenes are red grapes, blueberries, cranberries, peanuts and dark chocolate.
Phenolic Acids
Phenolic acids are made up of hydroxybenzoic acids and hydroxycinnamic acids. They are known for their antioxidant activity neutralizing free radicals and reducing oxidative stress in the body. Similar to other polyphenols they offer various health benefits, including anti-inflammatory, anti-cancer properties and promote good cardiovascular health. Foods high in phenolic acids are berries, apples, spinach, artichokes, whole grains, coffee, tea, and nuts.
Health Benefits of Polyphenols
Antioxidant Properties
Polyphenols are potent antioxidants that help neutralize harmful free radicals in the body, protecting cells from oxidative stress and reducing the risk of chronic diseases.
Anti-Inflammatory Effects
Many polyphenols have been shown to exhibit anti-inflammatory properties which contribute to the prevention and management of inflammatory conditions.
Heart Health
Polyphenols have been shown to improve blood vessel function, resulting in reduced blood pressure, and lower cholesterol levels leading to improved cardiovascular health.
Cancer Prevention
Some polyphenols, particularly flavonoids, have shown potential in inhibiting the growth of cancer cells and reducing the risk of certain cancers (Bhosale et al, 2020).
Brain Health
Polyphenols may support cognitive function and protect against neurodegenerative diseases like Alzheimer's by reducing oxidative stress and inflammation.
Blood Sugar Regulation
Certain polyphenols can help regulate blood sugar levels, making them beneficial for individuals with diabetes or those at risk of developing the condition.#
Sources of Polyphenols
Fruits - Berries, apples, citrus fruits, cherries, grapes, and pomegranates.
Vegetables - Spinach, kale, broccoli, onions, artichokes, and red cabbage.
Whole Grains - Oats, barley, and quinoa.
Legumes - Beans, lentils, and peas.
Nuts and Seeds - Almonds, walnuts, flaxseeds, and chia seeds.
Tea - Green tea, black tea, and white tea.
Coffee - coffee beans (beans or freshly ground are preferred over freeze dried/ instant)
Herbs and Spices - Cloves, cinnamon, oregano, and turmeric.
Dark Chocolate - Dark chocolate (the higher the percentage the better)
Polyphenols contain a myriad of health benefits such as antioxidant, anti-inflammatory and anticancer properties. They are available from an array of fruits, vegetables, teas, and whole grains. Diversifying your diet with a wide variety of these foods is an investment in your health. Adopting a diet rich in plant-based foods will not only increase your polyphenol intake but comes with a host of other benefits associated with high fruit, vegetable, and whole grain intake.
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