Eating more polyphenols can help you live a longer, healthier life – here’s why and what to eat | Canada Voices

If your regular diet doesn’t include berries, walnuts, leafy greens and spices, it should.

These are only a handful of foods that are packed with polyphenols, plant compounds thought to contribute significantly to cardiovascular, metabolic, brain and gut health.

These powerful compounds are a compelling reason to add more plants to your everyday diet. Here’s a breakdown of their studied health benefits and which foods you’ll find them in.

How can I eat well to ensure better brain health? Nutrition expert Leslie Beck answered your questions

What are polyphenols?

Polyphenols are a large and diverse group of compounds produced by plants that contribute to a species’ colour and flavour. There are 8,000 known types, each belonging to one of four major classes.

These are flavonoids (found in berries, citrus, apples, leafy greens, soybeans, tea, cocoa), phenolic acids (coffee, berries, whole grains, red onion, nuts, herbs, spices), stilbenes (berries, red grapes, peanuts) and lignans (flaxseeds, sesame, whole grains).

Polyphenols help protect plants from ultraviolet radiation and disease. Turns out, when we consume polyphenols, they protect us too.

How polyphenols support healthy aging

Polyphenols have potent antioxidant and anti-inflammatory effects. They’ve also been shown to improve blood vessel function, lower (bad) LDL cholesterol, increase (good) HDL cholesterol and reduce blood pressure.

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As well, polyphenols act as prebiotics, nourishing beneficial gut bacteria. They’re also believed to improve insulin secretion and the uptake of glucose into muscle cells.

Polyphenols have also been shown to improve blood flow to the brain. Some are able to cross the blood-brain barrier, shielding brain cells from oxidative stress and inflammation.

Research also suggests polyphenols may modestly help weight control by increasing fat oxidation (breakdown).

Polyphenols and longevity: what the science says

There’s strong evidence that a polyphenol-rich diet guards against cardiovascular disease. Many observational studies have tied higher daily polyphenol intake – especially from flavonoids – to a lower risk of heart disease, stroke and cardiovascular death.

Randomized controlled trials have also found polyphenol-rich diets reduce the incidence of heart attack, stroke and cardiovascular death.

The landmark five-year PREDIMED trial, published in 2018, found that among 7,447 older adults at elevated risk for cardiovascular disease, those who ate a Mediterranean diet enriched with olive oil or nuts (both high in polyphenols) experienced 30 per cent fewer major cardiovascular events than participants assigned to a low-fat diet.

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Several observational studies have associated diets plentiful in polyphenol-rich foods – especially berries, tea, cocoa, leafy greens and soy – with improved insulin sensitivity and a lower risk of Type 2 diabetes.

The PREDIMED trial found a 30 to 40 per cent lower risk of diabetes among participants in the Mediterranean diet groups compared with those in the low-fat diet group.

There’s growing evidence, too, that a polyphenol-rich diet can slow age-related cognitive decline.

Studies conducted in older adults have linked long-term adherence to a high-polyphenol diet to better cognitive function.

Evidence from randomized controlled trials, while still limited, suggests that increasing polyphenol intake can improve cognition and/or delay cognitive decline, especially in older adults at increased risk for cardiovascular disease.

Foods to boost your daily polyphenol intake

While there is no established recommended daily intake for polyphenols, studies have linked higher intakes in the range of 500 to 1,500 milligrams a day with a lower risk of chronic disease. It’s best to include a variety of polyphenol-rich foods in your diet since different types provide distinct benefits and can have complementary effects.

The polyphenol content of a plant can vary, sometimes widely, depending on factors such as temperature, sunlight, soil composition, time of harvest and postharvest storage conditions.

One cup of wild blueberries, for example, contains 600 to 1,000 milligrams of polyphenols, mainly as flavonoids called anthocyanins. One cup of cultured blueberries, meanwhile, is also an exceptional source but has 400 to 500 milligrams.

Strawberries provide about 340 mg of polyphenols in each cup. One medium red apple, with skin, supplies 200 to 300 mg, and one cup of red grapes has 120 to 130 mg.

One cup of artichoke hearts contains approximately 415 mg of polyphenols. A cup of cooked kale provides roughly 90 to 120 mg and one cup of raw spinach supplies 35 to 50 mg.

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One ounce of walnuts (14 halves) has 300 to 450 mg of polyphenols. An ounce of hazelnuts contains 140 mg. Two tablespoons of ground flax contain 200 to 300 mg of polyphenols.

One cup of cooked black beans delivers 260 to 330 mg of polyphenols, while the same amount of red kidney beans has 340 to 370 mg.

When it comes to beverages, you’ll find 120 to 300 mg of polyphenols in 240 millilitres of green tea and 100 to 200 mg in 240 ml of black tea. Longer steep times and higher quality loose-leaf teas yield higher amounts.

A 240 ml cup of coffee, meanwhile, offers 200 to 400 mg of polyphenols, with light-roasted beans having more than dark-roasted ones.

Other good sources include cocoa and dark chocolate, as well as dried herbs and spices, especially cloves, cinnamon, turmeric, peppermint, oregano, thyme, rosemary and sage.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.