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Polyphenol

Polyphenols featured article

Polyphenols comprise a group of antioxidant compounds found in a variety of plants consumed as foods and beverages. Polyphenols are one of the most common classes of bioactive compounds found in plants, along with alkaloids (e.g., berberine), organosulfur compounds (e.g., sulforaphane), and terpenoids (e.g., beta carotene). A growing body of evidence suggests that polyphenols have disease-fighting properties, although the evidence to support these claims varies in quality.

Research has demonstrated some degree of efficacy of polyphenol consumption for:

  • reducing intestinal hyperpermeability (i.e., leaky gut syndrome)
  • increasing antioxidant defenses
  • reducing cardiovascular disease risk
  • ameliorating metabolic syndrome
  • improving memory, cognitive function, and mood
  • promoting good quality sleep

Chemically, polyphenols...

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Q&A #69 with Dr. Rhonda Patrick (4/5/25)

Posted on April 28th 2025 (about 1 month)

Dr. Rhonda Patrick covers lithium microdosing, reducing homocysteine, aluminum's link to cancer, and beta-alanine and alpha-lipoic acid supplements.

polyphenol

Why I Stopped Adding Bananas to My Smoothies

Posted on January 20th 2025 (5 months)

In this clip, Dr. Rhonda Patrick explains how PPO in bananas affects polyphenols and how vitamin C acts as an inhibitor.

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Q&A #64 with Dr. Rhonda Patrick (11/2/24)

Posted on November 19th 2024 (7 months)

Dr. Rhonda Patrick discusses silicone safety, grounding, pentadecanoic acid, and the potential benefits of olive leaf extract and peptides.

Topic Pages

  • Cocoa flavonoids (chocolate)
    stub

    Chocolate cocoa flavonoids are polyphenolic flavan-3-ols that scavenge reactive oxygen species and enhance endothelial nitric-oxide synthase activity.

  • Intestinal permeability

    Polyphenols reduce intestinal permeability by activating AMPK and Nrf2 pathways that upregulate tight-junction proteins occludin and claudin.

  • Polyphenol-rich diets and neurodegeneration (glycemic control)
    stub

    Polyphenols and polyphenol-rich diets improve glycemic control, reducing AGE-induced oxidative-neuroinflammatory damage underlying neurodegeneration.

  • Polyphenols

    Polyphenols are secondary plant metabolites with multiple phenolic hydroxyls that scavenge reactive species via hydrogen-atom or electron donation.

News & Publications

  • Anti-inflammatory treatments, particularly omega-3 fatty acids and plant-based compounds, effectively reduce depression symptoms in older adults. www.nature.com
    Omega-3 Inflammation Depression Mental Health NSAID Polyphenol

    Inflammation and depression are often linked, particularly in older adults, who tend to experience chronic low-grade inflammation and elevated rates of depression. A recent study found that anti-inflammatory interventions may help reduce symptoms of depression and the risk of developing depression in older adults.

    Researchers conducted a systematic review and meta-analysis of 31 randomized, placebo-controlled trials that assessed the effects of anti-inflammatory therapies on depression in older adults. The various anti-inflammatory agents included omega-3 fatty acids, nonsteroidal anti-inflammatory drugs, and plant-based compounds. The researchers included only trials with at least 20 participants.

    The analysis revealed that anti-inflammatory treatments were more effective than placebos in reducing depression symptoms among older adults. On average, people receiving these treatments exhibited a moderate improvement in symptom severity compared to those taking a placebo. Omega-3 fatty acids and plant-based compounds, such as curcumin and soy protein, appeared particularly beneficial. There was also some evidence suggesting that these treatments might help prevent depression, although the results were not statistically conclusive.

    These findings suggest that targeting inflammation is a promising strategy for managing depression in older adults, especially those with chronic inflammation. Learn more about links between inflammation and depression in Aliquot #36: Inflammation and Depression, part 2

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  • Strawberry consumption boosts thinking speed and lowers systolic blood pressure by 3% in older adults. www.sciencedirect.com
    Nutrition Diet Heart Disease Memory Blood Pressure Polyphenol Cardiovascular

    Cognitive decline and cardiovascular disease often go hand in hand—and both become more common with age. Nutrition plays a key role in protecting brain and heart health, and certain fruits rich in antioxidants may offer targeted benefits. A recent study found that consuming fresh strawberries daily improved cognitive function and lowered systolic blood pressure by an average of 3% in older adults.

    Researchers provided 35 healthy adults, ages 60 to 78, a strawberry powder or a placebo each day for eight weeks. Each person tried both options in random order, with a four-week break in between. The strawberry powder, made from freeze-dried fruit, delivered the same nutrients and antioxidants as two cups of fresh strawberries. The researchers measured the participants' cognitive function using standard tests and tracked markers of heart health, including blood pressure, waist size, blood lipids, and antioxidant levels.

    The participants' thinking speed improved during the strawberry phase, while episodic memory improved modestly during the placebo phase. After eight weeks of strawberry consumption, systolic blood pressure dropped by an average of 3%, and waist size decreased slightly. Participants' blood antioxidant capacity increased with strawberries but decreased with the placebo. Triglycerides increased during the placebo period but remained stable with strawberries.

    The findings from this small study suggest that regular strawberry intake supports brain and heart health in older adults. Strawberries are rich in polyphenols. Learn more about polyphenols in our overview article.

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  • Regular green tea consumption correlates with fewer cerebral white matter lesions, potentially reducing the risk of stroke, dementia, and disability. www.nature.com
    Brain Aging Green Tea Dementia Polyphenol

    About half of your brain is white matter—a network of nerve fibers that allow for the exchange of information and communication within the brain. Aging and lifestyle factors can damage the white matter, increasing the risk of stroke, dementia, and disability. However, a recent study found that the brains of regular green tea drinkers have fewer white matter lesions than non-drinkers.

    The study included nearly 8,800 older adults living in Japan. Participants provided information about their green tea and coffee consumption and underwent magnetic resonance imaging to assess their brain health and volume.

    They found that higher green tea consumption correlated with fewer cerebral white matter lesions but had little effect on brain volumes, even after accounting for demographic, lifestyle, and health factors. People who drank about three cups (~20 ounces) of green tea daily had 3% less white matter damage in their brains than those who drank just one cup (~7 ounces). Those who drank around seven to eight glasses (~50 ounces) daily had 6% less damage. Coffee consumption did not affect white matter or brain volume, suggesting that green tea protects against white matter damage.

    Green tea contains epigallocatechin gallate (EGCG), a polyphenolic compound that exerts robust antioxidant, anti-inflammatory, and neuroprotective effects. Evidence suggests that EGCG reduces the buildup of amyloid beta and tau—two proteins involved in the pathophysiology of Alzheimer’s disease. Learn more about EGCG and other polyphenols in our overview article.

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  • A diet abundant in antioxidants, iron-chelating nutrients, and polyunsaturated fatty acids mitigates harmful iron accumulation in the brain, preserving cognitive function. www.sciencedirect.com
    Brain Diet Iron Polyphenol

    Although iron is essential for many physiological processes in the body, it can also be harmful, inducing oxidative stress and hindering neurogenesis. The body typically stores iron in protein complexes until needed, but these storage processes decline with age, leading to iron accumulation in body tissues. A recent study revealed that iron can build up in the brain, impairing cognitive function. Nevertheless, dietary components can help reduce iron accumulation in the brain and maintain cognitive health.

    Researchers examined the brain health of 72 cognitively healthy older adults by conducting brain scans at baseline and two to three years later. Participants provided details about their dietary habits, physical activity, and overall health. They also underwent cognitive tests that evaluated their episodic memory and executive function.

    The brain scans revealed that iron levels increased markedly over time, and higher iron accumulation correlated with poorer cognitive function. However, a higher intake of antioxidants, vitamins, iron-chelating nutrients, and polyunsaturated fatty acids mitigated iron accumulation. Iron-chelating nutrients include polyphenolic compounds, such as gallic acid and catechins (in tea), caffeic acid (in coffee), quercetin (in apples and onions), ellagic acid (in walnuts and pomegranates), curcumin (in turmeric) and others.

    These findings suggest that diet mitigates iron accumulation in the brain, ultimately influencing cognitive health. Interestingly, alcohol can promote iron accumulation in the brain. Learn more in this episode featuring Dr. Rhonda Patrick.

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  • Mediterranean diet variations, rich in polyphenols and targeted at metabolic health, halve brain atrophy markers, slowing age-related brain shrinkage by up to 50% over 18 months. www.sciencedirect.com
    Brain Diet Aging Polyphenol

    Brain atrophy occurs naturally with aging, but certain factors such as type 2 diabetes, high blood pressure, and inflammation can accelerate this process, increasing the risk of cognitive decline. However, eating a healthy diet may help slow brain aging. A recent study found that two versions of the Mediterranean diet reduced markers of brain atrophy by 50% over 18 months compared to general healthy eating guidelines.

    Researchers assigned participants aged 50 or older with abdominal obesity or abnormal blood lipids to one of three diets: one that followed standard healthy dietary guidelines, a calorie-restricted Mediterranean diet (which included walnuts and olive oil and substituted chicken and fish for lamb and beef), or a “green” calorie-restricted Mediterranean diet enriched with polyphenols from green tea and mankai, an aquatic plant. The participants underwent brain imaging to assess hippocampal atrophy, a key marker of brain aging, and the researchers tracked changes in body weight, blood sugar, and inflammation over the study period.

    Participants following the green Mediterranean diet showed the greatest preservation of brain volume, particularly in the hippocampus. They also experienced improvements in HbA1c (a marker of long-term blood glucose control), insulin resistance, fasting glucose, and C-reactive protein. Improvements in blood sugar levels and inflammation were closely linked to better brain health outcomes, and greater intake of polyphenol-rich foods like mankai and green tea further enhanced these benefits.

    Mankai, also called duckweed, is rich in polyphenols, omega-3 fatty acids, dietary fiber, and many micronutrients, including iron and vitamin B12. The polyphenols in mankai exert robust antioxidant activity and support healthy blood glucose levels—critical elements in maintaining brain health.

    These findings suggest that diets rich in polyphenols and designed to improve metabolic health may help protect against age-related brain atrophy and keep the brain biologically younger. Learn more about the health benefits of polyphenols in our overview article.

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  • Daily cinnamon supplementation averaging 2,100 milligrams – roughly a teaspoon – shows promise in managing type 2 diabetes. pubmed.ncbi.nlm.nih.gov
    Diet Diabetes Insulin Resistance Insulin Polyphenol

    Cinnamon is one of the most consumed spices in the world, popular in both sweet and savory dishes in many cuisines. Evidence suggests cinnamon improves lipid profiles and protects against damage induced by oxidative stress. A recent systematic review and meta-analysis found that cinnamon helps maintain healthy blood glucose levels and reduces insulin resistance in people with type 2 diabetes.

    Researchers analyzed the findings of 24 clinical trials investigating the effects of cinnamon supplementation on blood glucose levels. The various trials included more than 1,800 participants from 11 nations.

    The analysis revealed that cinnamon supplementation reduced fasting blood glucose levels, hemoglobin A1c concentrations, and insulin resistance (without lowering insulin) in people with type 2 diabetes. The trials varied in duration from six to 16 weeks, and daily cinnamon doses ranged from 120 to 6,000 milligrams, averaging 2,100 milligrams – roughly a teaspoon.

    These findings suggest that cinnamon improves symptoms of type 2 diabetes and may be a valuable adjunct to traditional therapies. Cinnamon is rich in polyphenols, a broad class of plant bioactive compounds. Learn more about polyphenols in our overview article.

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  • Naringenin, a citrus fruit flavonoid, preserves muscle mass in aging while enhancing exercise capacity and aerobic metabolism efficiency (animal study). medicalxpress.com
    Nutrition Aging Muscle Polyphenol

    Muscle mass declines markedly with age, with up to 8 percent muscle mass loss occurring per decade after age 30. Evidence suggests that naringenin, a flavonoid compound found in citrus fruits, maintains muscle mass in aging. Mice that ate a diet supplemented with naringenin showed improved muscle endurance and grip strength.

    Researchers supplemented the diets of young adult mice, middle-aged mice, and mice prone to muscular dystrophy (accelerated muscle loss) with naringenin. Then, they assessed naringenin’s effects on exercise capacity and aerobic metabolic levels in skeletal muscle.

    They found that young adult and middle-aged mice receiving naringenin could run farther than those that did not. Middle-aged mice also showed improved grip strength and increased calf muscle size. Mice prone to developing muscular dystrophy ran farther and showed improved grip strength.

    The researchers attributed these improvements in muscle endurance to naringenin’s capacity to increase the number of oxidative myofibers (muscle fibers that use oxygen) and improve the overall efficiency of aerobic metabolism in the body. They found that Sp1, a transcription factor that influences gene expression in muscle, likely mediated naringenin’s effects.

    These findings indicate that naringenin may preserve muscle mass in aging and disease. Other dietary components, such as omega-3 fatty acids, influence muscle maintenance, too. Learn more in this episode featuring Dr. Chris McGlory.

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  • Eating a polyphenol-rich diet may cut abdominal fat. bmcmedicine.biomedcentral.com
    Diet Polyphenol Visceral Fat

    Eating a Mediterranean-style diet, which is abundant in polyphenol-rich fruits, vegetables, olive oil, legumes, and nuts, helps reduce abdominal fat, a 2022 study found. People who followed a Mediterranean-style diet supplemented with a polyphenol-rich shake for 18 months lost twice as much abdominal fat as those who consumed a lower-polyphenol diet.

    Researchers assigned nearly 300 people to follow one of three diets plus exercise: a Mediterranean-style diet that included walnuts; a Mediterranean-style diet that included walnuts, green tea, and a shake that contained duckweed (a polyphenol-rich aquatic plant native to Asia); and a diet that adhered to conventional healthy dietary guidelines. They measured the participants' body weight and waist circumference and conducted magnetic resonance imaging (MRI) studies to assess their abdominal fat at the beginning and end of the intervention.

    They found that participants who followed the two variations of the Mediterranean/walnut diets lost body weight and their waist circumferences decreased, compared to those who followed the healthy dietary guidelines. However, MRIs revealed that while those who followed the Mediterranean/walnut diet lost 6.0 percent of their abdominal fat, those who followed the Mediterranean/walnut diet that included tea and duckweed lost 14.1 percent of their abdominal fat – more than twice as much.

    Walnuts are rich in the polyphenolic compound ellagic acid. Bacteria in the human gut break down ellagic acid to produce urolithins. Scientists have identified about 20 urolithins, but the most studied of these is urolithin A, which exerts potent anti-obesity effects.

    Duckweed is rich in polyphenols, carotenoids, omega-3 fatty acids, fiber, and many micronutrients, including iron and vitamin B12. The polyphenols in duckweed exert robust antioxidant activity and support healthy blood glucose levels – critical elements in maintaining healthy body weight and waist circumference.

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  • Pomegranate juice improves blood pressure and reduces arterial plaques in people with atherosclerosis. www.clinicalnutritionjournal.com
    Blood Pressure Polyphenol Cardiovascular

    Pomegranate juice reduces symptoms associated with the narrowing of arteries that supply the brain, a small study has found. Patients who drank pomegranate juice for one year experienced improvements in blood pressure, antioxidant status, and carotid artery thickness (an indicator of the extent of plaque buildup in the arteries).

    The study involved 19 people who had atherosclerosis with carotid artery stenosis, a condition in which the arteries that supply the brain thicken and narrow due to the accumulation of plaque. Ten of the participants drank 50 milliliters (about 1.7 ounces) of pomegranate juice daily for one year, while the remaining nine participants did not consume any pomegranate juice. The researchers assessed various aspects of the participants' cardiovascular health before, during, and after the intervention.

    They found that several parameters of cardiovascular health improved after one year of pomegranate juice consumption. For example, the participants' carotid artery thickness decreased by up to 30 percent and their blood pressure decreased by 21 percent. In addition, their total antioxidant status increased by 130 percent. Participants who didn’t drink pomegranate juice did not experience these improvements, and in some cases, their cardiovascular measures worsened.

    This small study shows that drinking pomegranate juice may improve symptoms associated with narrowing of the arteries. Pomegranates are rich in various bioactive polyphenols, including tannins, ellagic acid, and anthocyanins, that exert potent antioxidant, anti-inflammatory, or cardioprotective effects in humans.

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  • How cranberries could improve memory and ward off dementia www.sciencedaily.com
    Memory Dementia Polyphenol

    Eating polyphenol-rich cranberries improves memory and neural functioning in older adults.

    As many as 55 million people worldwide have dementia, a figure expected to triple in the next three decades. Evidence suggests that dietary patterns and components may reduce the risk of developing dementia. Findings from a recent study suggest that eating cranberries improves memory and neural functioning in older adults.

    Cranberries, like many other red, purple, or blue fruits, are rich in bioactive compounds called polyphenols, including anthocyanins, proanthocyanidins, flavonols, and others. Robust evidence indicates that these compounds exert antioxidant, anti-inflammatory, and/or neuroprotective effects in humans.

    The investigators conducted a randomized, placebo-controlled trial involving 60 healthy adults between the ages of 50 and 80 years. Half of the participants consumed 4.5 grams of freeze-dried cranberry powder (to be mixed in liquid) every day for 12 weeks. The daily portion of supplemental cranberry powder was roughly equivalent to eating about one-half cup of fresh cranberries and provided 59 milligrams of anthocyanins, 281 milligrams of proanthocyanidins, and 20 milligrams of flavonols. The other half of the participants consumed a similar-looking non-nutritive powder for the duration of the study. Before, during, and after the intervention, participants underwent cognitive testing and provided blood samples for biochemical assessment. A subset of participants underwent magnetic resonance imaging (MRI) studies.

    At the end of the intervention, participants who received the cranberry powder exhibited improvements in visual episodic memory. In addition, their low-density lipoprotein cholesterol (which contributes to atherosclerosis and impaired brain function) decreased. The MRIs revealed that the supplemented group had increased blood flow to areas of the brain involved in memory formation and consolidation.

    These findings suggest that polyphenol-rich cranberries improve memory and aspects of neural functioning in older adults. It is noteworthy, however, that many commercial cranberry products contain copious amounts of added sugar to counter the berries' tartness. Because sugar can have harmful effects on brain and metabolic health, consuming unsweetened cranberries (or other berries) will likely have the greatest benefits on cognition.

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  • Combined anthocyanins and bromelain supplement improves endothelial function and skeletal muscle oxygenation status in adults: a double-blind placebo- pubmed.ncbi.nlm.nih.gov
    Polyphenol

    A combined pineapple and berry supplement improves vascular function.

    Cardiovascular disease is a major public health threat, with deaths from cardiovascular diseases expected to reach 23 million by 2030. A diet rich in fruits and vegetables is known to reduce heart disease risk, in part due to the antioxidant and anti-inflammatory compounds provided by the diet that reduce oxidative stress and improve vascular function. Findings from a new report show that a supplement containing bromelain and anthocyanin antioxidants improves blood vessel function and muscle oxygenation.

    Bromelain is a compound found in pineapple that breaks down protein, called a protease. In the kitchen, bromelain is used to tenderize meat, but in the medical field, topically applied bromelain is an approved treatment to promote wound healing. Research shows that bromelain has anti-inflammatory and antithrombotic properties that may improve vascular function and reduce cardiovascular disease risk. Anthocyanins are blue- and purple-colored pigments found in fruits and vegetables that absorb free radicals in the blood stream, reduce inflammation, and reduce blood pressure.

    The authors recruited 18 healthy adults who engaged in regular recreational physical activity and randomly assigned them to receive either a placebo or a supplement containing 465 milligrams of hawthorn extract (source of anthocyanins), 480 milligrams of tart cherry powder (source of anthocyanins), and 400 milligrams of bromelain. One hour after the participants consumed the treatment, the researchers measured heart rate, blood pressure, flow mediated dilation (a measure of endothelial function), muscle oxygenation, and muscle fatigue and collected a blood sample. The participants returned two weeks after their first visit and repeated the same testing after receiving the treatment (placebo or anthocyanin+bromelain) they did not receive the first time.

    The anthocyanin+bromelain supplement led to a marked increase in total serum antioxidant capacity. Participants consuming the active supplement experienced a statistically significant increase in flow mediated dilation and reduction in systolic blood pressure. The anthocyanin+bromelain supplement increased muscle oxygenation during a leg extension exercise, but did not affect diastolic blood pressure, resting heart tate, or muscle fatigue.

    These results show that supplementation with anthocyanins and bromelain acutely improves vascular function in healthy adults; however, additional research is needed to understand the long-term effects of supplementation on cardiovascular disease risk.

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  • Eating spices reduces chronic inflammation. academic.oup.com
    Inflammation Immune System Polyphenol Lipopolysaccharide

    Obesity causes chronic inflammation, which promotes atherosclerosis and cardiovascular disease. Previous research suggests that spices such as cinnamon, cumin, and ginger exert short-term anti-inflammatory effects; however, studies with longer durations are needed to confirm these findings. Authors of a recent study found that four weeks of spice consumption reduced inflammation and altered monocyte function in adults at risk of cardiometabolic disease.

    Monocytes are white blood cells that respond to infection by promoting inflammation. Obesity and dyslipidemia cause inappropriate activation of monocytes, promoting chronic inflammation in the arteries. Pro-inflammatory monocytes carrying excess lipids, called foam cells, accumulate in arterial walls, narrowing the arteries and restricting blood flow. Consuming spices that contain anti-inflammatory bioactive compounds may help reduce cardiovascular disease risk.

    The authors recruited 71 participants and assigned them to consume a standard American diet with added spices in three doses: low (a dash), medium (a quarter teaspoon), or high (a half teaspoon). Participants consumed each dose of spices for four weeks and completed the doses in random order. The spice mixture contained the most common spices used in the United States, the most abundant of which were cinnamon, coriander, ginger, cumin, and parsley. Participants provided blood samples at multiple points throughout the study. Finally, the investigators isolated monocytes from the participants’ blood and exposed the cells to bacterial endotoxin in order to promote inflammation.

    Compared to baseline, participants had lower fasting serum levels of the pro-inflammatory cytokine interleukin-6 following four weeks of the medium dose spice blend. The monocytes from these participants also secreted less interleukin-6 when challenged with bacterial endotoxin. Participants consuming the medium and high spice blends had fewer foam cells and more conventional monocytes than participants consuming the low spice blend.

    The authors concluded that spices reduced fasting inflammation and altered monocyte behavior. They did not know why the medium dose was more effective in reducing inflammation than the high dose, but they hypothesized that the high dose of spices may have contained such a high level of polyphenols that it promoted oxidative stress. More research is needed to test this hypothesis. This study was funded by the McCormick Science Institute.

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  • Drinking oolong tea promotes fat burning. www.eurekalert.org
    Obesity Green Tea Polyphenol

    Tea from the leaves of the Camelia sinensis plant is one of the most widely consumed beverages worldwide. Its consumption is associated with a variety of beneficial health effects. Findings from a recent study suggest that oolong tea consumption promotes weight loss.

    Many types of tea from Camelia sinensis exist, but they are generally classified as green, oolong, or black. The differences in the three types arise during processing, where they undergo various degrees of oxidation. Green tea is unoxidized; oolong tea is partially oxidized; and black tea is fully oxidized. Tea contains several bioactive compounds, including catechins and caffeine. Catechins are polyphenolic compounds that exert antioxidant properties. Caffeine is a potent stimulant.

    The intervention study involved 12 healthy non-obese men between the ages of 20 and 56 years. The participants consumed one of three beverages at breakfast and lunch for three 14-day sessions: oolong tea containing 51.8 milligrams of caffeine and 48.5 milligrams of catechins; a beverage containing 51.8 milligrams of caffeine; or a placebo beverage. A washout period of about two weeks separated each session. The men drank no other beverages containing caffeine or alcohol during the study period. They underwent 24-hour indirect calorimetry to monitor their metabolism and polysomnographic sleep recording to gauge their sleep quality.

    The authors of the study found that fat oxidation increased by roughly 20 percent when the participants drank the oolong tea or pure caffeine beverage, but not when they drank the placebo beverage. The effects of consuming oolong tea continued to a greater degree while the participants were asleep. Neither of the caffeine-containing beverages promoted an increase in the men’s energy expenditure, and none of the men exhibited alterations in sleep quality, suggesting that they developed a tolerance to the stimulatory effects of caffeine.

    These findings suggest that oolong tea stimulates fat oxidation, especially during the overnight fast.

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