Polyphenols: The Secret Plant Compounds Linked to Longevity

Plant-based foods have long been associated with better health and a lower risk of lifestyle diseases. Most people assume that their benefits are linked solely to their nutritional complexity as they deliver a variety of vitamins and minerals, along with plenty of dietary fibre. While this is true, and plant-based foods are absolutely essential for balanced nutrition, they may also hold the secret to a longer life. This much sought-after benefit has been linked to the presence of compounds in plants, called polyphenols. You’ve probably heard influencers talk about them or seen posts on Instagram about them, but what is the connection between polyphenols and longevity, and is there any truth to the claims?

Although polyphenols have only become a trendy buzzword in recent years, scientists have been studying them for decades. So, we have plenty of evidence from which we can find clear answers.

What are polyphenols?

Polyphenols are naturally occurring compounds that are found specifically in plant-based foods, such as vegetables, fruits, nuts, seeds, grains, spices, herbs, teas, wine, and dark chocolate. These compounds exhibit strong health-promoting or protective effects, which adds to the health benefits derived from eating plant-based foods. There are also different types of polyphenols, which is why certain foods are associated with very specific health benefits. For example, garlic is known to help fight infections with strong antimicrobial effects, while berries are known to boost brain and heart health.

Research shows that there are, in fact, over 10,000 types of polyphenols, and we still have much more to discover and understand. Based on current knowledge, there are five main categories of polyphenols, including flavonoids, phenolic acids, lignans, stilbenes, and tannins. The primary purpose of polyphenols in plants appears to be for protection against a variety of threats, from exposure to UV radiation and diseases to insects and environmental stressors. When we consume plants as food, some of these compounds also provide us with protection.

Why polyphenols are key to healthy ageing

When we consume plant-based foods that contain polyphenols, they usually work as antioxidants in the body. This is the main mechanism of action that offers immense health benefits, reducing health risks posed by exposure to environmental and other risk factors such as UV damage and pollution. Research suggests that diets that include a good amount of polyphenol-rich foods may also offer protection against chronic diseases and age-related degenerative conditions. While antioxidant protection does explain many of these benefits, there are also other mechanisms at work.

Many polyphenols protect against ageing by reducing inflammation and cellular senescence, which is a process in which cells stop dividing and release harmful molecules. Some polyphenols may also slow ageing by enhancing gut health and supporting mitochondrial function. We have seen, from some studies, that polyphenols like quercetin and resveratrol support the repair of damaged mitochondria, while other polyphenols can induce autophagy, which is a process of clearing damaged proteins and organ parts that can give rise to age-related degenerative diseases.

A 2024 review published, involving more than 150,000 participants across several studies, pointed to a 7% reduction in all-cause mortality. This has been supported by other studies as well, with some indicating that high polyphenol diets may have an even stronger association with increased longevity.

Health benefits of polyphenols

Polyphenols have been linked with a variety of health benefits, including the following:

Lower risk of premature death

A 2024 meta-analysis of seven cohort studies involving 178,657 adults found that higher dietary polyphenol intake was associated with a 7% reduction in all-cause mortality.

Neuroprotective

Cognitive decline is a major concern in ageing, and polyphenol-rich foods may offer protection against it. Studies suggest that high polyphenol intake can improve blood flow to the brain, strengthen memory, and boost focus. Polyphenols in wine have even been linked with a 29% lower risk of dementia.

Cardioprotective

Plant-based diets are highly recommended for heart health as they reduce inflammation, lower blood pressure, and improve lipid levels, reducing the risk of heart disease. These benefits are attributed to the antioxidant effects of polyphenols. Studies also show that higher dietary intake of some polyphenols, such as isoflavones from soy and lignans from flax seeds, can lower the risk of cardiovascular mortality by over 40%. Meta-analyses of randomized trials indicate that polyphenol-rich foods or extracts lead to meaningful cardiovascular benefits, including an average reduction of ~3.7 mmHg in systolic blood pressure, lower triglyceride and total cholesterol levels, and improved vascular function as measured by flow-mediated dilation.

Anti-diabetic

Polyphenols can help in diabetes prevention and management through various mechanisms. In addition to reducing systemic inflammation, they can slow or prevent the breakdown of starch into simple sugars and improve insulin production and sensitivity, keeping blood sugar levels stable. Research shows that the risk of developing diabetes can be reduced by as much as 57% with polyphenol-rich diets.

Cancer prevention

Population studies across the world point to a lower incidence of cancer in regions where people follow primarily plant-based diets with little intake of ultra-processed foods. This benefit is mainly linked to the antioxidant and anti-inflammatory effects of polyphenols. Some of these plant compounds have even been found to inhibit the growth of cancerous cells in laboratory settings.

Gut-friendly

Polyphenols promote gut health directly by encouraging the growth of good bacteria, while limiting populations of harmful bacteria such as E. coli and Salmonella. Anti-inflammatory and antioxidant effects can also protect the intestinal barrier and lower the risk of inflammatory bowel diseases.

Polyphenol-rich foods to include in your diet

When trying to include more polyphenol-rich foods in your diet, focus on the following.

• Dark and brightly coloured fruits and veggies such as brinjal, beetroot, purple cabbage, spinach, kale, plums, and pomegranates.
  
  
• Blueberries are one of the healthiest polyphenol-rich foods, but all berries are a good source of polyphenols, including strawberries and raspberries.
  
  
• Beans are also rich in polyphenols, with darker varieties such as kidney beans or rajma and black beans being particularly good choices.
  
  
• Coffee and tea, including green and black tea, are among the richest sources of polyphenols.
  
  
• Herbs and spices like cloves, ginger, mint, turmeric, cinnamon, and oregano don’t just add flavour to meals but are also some of the best sources of polyphenols.
  
  
• Nuts and seeds like almonds, walnuts, flaxseeds, and chia seeds, as well as some seed oils and olive oil, are also polyphenol-rich foods.

Make polyphenols part of your longevity strategy

Adding more polyphenols to your regular diet shouldn’t be challenging if you follow some simple advice. Simply make sure to follow the plate rule, which recommends a half plate serving of fruits and vegetables, while the other half may be divided equally between lean protein (foods like beans, fish, and poultry) and healthy carbohydrates (whole grains and starchy vegetables). Keep it varied and colourful to ensure that you get balanced nutrition and a variety of polyphenols from different sources, as they all offer unique health benefits that work together to promote longevity and healthy ageing.

Frequently Asked Questions

1. Do polyphenols really promote longevity?

Decades of research show that polyphenols offer a wide range of health benefits, which can help increase longevity through a variety of mechanisms.

2. What are the best sources of polyphenols?

All plant-based foods are healthy, but spices and dried herbs are particularly concentrated sources of polyphenols, while dark chocolate comes quite close.

3. Can polyphenols help prevent diabetes?

Yes, some studies show that polyphenol-rich diets can lower the risk of diabetes by as much as 57%.