Polyphenols: The Plant Compounds Your Microbiome Loves

Stand in any grocery aisle this spring and you will notice a new number on the olive oil shelf: a polyphenol count, printed in bold, sometimes bigger than the brand name. Short videos ranking oils, teas and dark chocolates by that figure have pulled in hundreds of millions of views, and searches for polyphenols have climbed with them. As of March 2025, the word has moved from nutrition journals to lunchroom conversation.

The attention is not entirely misplaced. Polyphenols are among the most studied compounds in food science, and a quiet shift in that science explains the buzz: researchers now think the benefit depends less on the compounds themselves and more on what your gut bacteria do with them.

That reframing is more interesting, and more useful, than any number on a label. Here is what the evidence supports, where it thins out, and how to put it to work at the table.

What are polyphenols, in plain language?

Polyphenols are a large family of compounds that plants make to defend themselves against sunlight, insects and infection. The name comes from their chemistry: each molecule carries several (poly) ring-shaped structures called phenol groups. More than 8,000 have been identified, and they are the reason blueberries are blue, coffee is bitter and a good olive oil catches the back of your throat.

Scientists sort them into four main classes. Flavonoids are the biggest group and include the anthocyanins in berries, the flavanols in cocoa and tea, and the quercetin in onions and apples. Phenolic acids dominate coffee and whole grains; chlorogenic acid is the one you drink every morning. Stilbenes include resveratrol, found in small amounts in grape skins and peanuts. Lignans sit in flaxseed, sesame and whole grains.

Polyphenols are not vitamins. You will not develop a deficiency disease without them, and no health agency sets a daily requirement. That distinction matters, because it tells you how to read the research. Trials test whether eating more of these foods changes risk over time, not whether a missing nutrient is being replaced. The MedlinePlus overview of antioxidants makes the same point: these compounds behave differently in a petri dish than in a person.

Where the compounds live also matters. Most polyphenols concentrate in the skin, peel and outer layers of plants, which is why whole fruit beats juice, why the bran of a grain carries more than the white interior, and why a peeled apple has lost a meaningful share of its quercetin before you take the first bite.

What changed recently: why polyphenols are trending

Three developments, stacked over a few years, explain the current surge.

First, the microbiome turn. Through the 2010s, studies tracked how polyphenols travel through the body, and a consistent finding emerged: only about 5 to 10 percent are absorbed in the small intestine. The rest reach the colon intact, where bacteria break them down. Reviews collected in PubMed now describe polyphenols as a two-way conversation, with the compounds reshaping the bacterial community and the bacteria deciding which active molecules the body actually receives. That idea gave the topic a fresh story, and social media picked it up.

Second, big trials reported. In 2022 the COSMOS trial, which followed more than 21,000 older adults in the United States for roughly three and a half years, found that a daily cocoa flavanol extract did not significantly lower the overall rate of cardiovascular events, the trial’s main question, though deaths from cardiovascular causes were about 27 percent lower in the cocoa group, a secondary finding that needs confirmation. A companion study found no benefit for memory. Those mixed results pushed researchers back toward whole foods.

Third, labels. Producers began printing polyphenol concentrations on extra virgin olive oil, building on a European health claim authorized back in 2012 for olive oil polyphenols and the protection of blood fats from oxidation. The number is real, but it was never designed as a consumer health score.

The Cleveland Clinic’s consumer summary, updated for this wave of interest, lands where most dietitians do: eat the foods, be skeptical of the extracts. The National Center for Complementary and Integrative Health takes a similar line on green tea, noting that research on brewed tea is encouraging but inconclusive, while concentrated extracts have been linked to rare liver injury.

What will polyphenols do to your body?

The honest answer begins with a surprise: very little of what you eat shows up in your bloodstream in its original form.

In the small intestine, a minority of smaller polyphenols are absorbed and quickly tagged by the liver with chemical groups that make them easier to excrete. Blood levels peak within one to two hours and fall within a day. This is why a single cup of green tea does not produce a lasting effect, and why most studies of blood markers require weeks of regular intake before anything shifts.

The larger share, often 90 percent or more, passes to the colon. Bacteria there strip off sugars, break open rings and produce a set of small molecules called phenolic metabolites. These are absorbed far more efficiently than the parent compounds, circulate longer, and are now thought to carry much of the biological activity once credited to the polyphenols themselves.

What do those metabolites do? Lab and animal work show they calm inflammatory signaling, support the lining of blood vessels so they relax more easily, and influence how cells handle glucose. Human trials, which are smaller and shorter, have measured modest improvements in blood pressure, in the flexibility of arteries, and in markers of insulin sensitivity after several weeks of cocoa, berries or olive oil.

The word to hold onto is modest. In healthy adults, a polyphenol-rich diet might lower systolic blood pressure by a few points, roughly what a brisk daily walk achieves. That is worthwhile at a population level, and meaningless as a replacement for prescribed treatment. The effect also appears to accumulate across many foods eaten over years rather than from any single hero ingredient.

Why your microbiome loves polyphenols

Your colon houses trillions of bacteria, and polyphenols act on them in two ways that look, from a distance, like gardening.

They weed. Many polyphenols have mild antimicrobial effects, and in human studies they tend to suppress bacteria associated with inflammation, such as certain Clostridium species, while leaving beneficial groups untouched. Cranberry, pomegranate and grape polyphenols have been shown in small trials and animal studies to increase Akkermansia muciniphila, a bacterium that lives in the mucus layer of the gut and is consistently more abundant in people with healthy metabolic profiles.

They feed. Although polyphenols are not fiber, they often arrive in the colon attached to fiber and sugars, and the bacteria that break them down thrive on the job. Bifidobacteria and Lactobacillus species, the same groups found in many fermented foods, increase in several trials of cocoa and berry intake.

The most striking example of this partnership is the ellagitannin story. Ellagitannins are polyphenols in pomegranates, walnuts, raspberries and strawberries. Humans cannot use them directly; specific gut bacteria convert them into molecules called urolithins, which are absorbed and appear to support the health of mitochondria, the energy-producing structures in cells. Only some people carry the bacteria to do this, which may explain why the same pomegranate juice produces measurable blood changes in one volunteer and nothing in the next.

That variability is one of the most important lessons of the last decade. Two people can eat identical diets and receive different chemistry from them. It also suggests a practical strategy: variety. A microbiome exposed to many different polyphenols across the week is more likely to carry the bacterial toolkit to use them.

What food is highest in polyphenols?

By weight, the champions are spices and herbs. A landmark 2010 analysis published in the European Journal of Clinical Nutrition, available through PubMed, ranked the 100 richest dietary sources, and cloves topped the list at roughly 15,000 mg per 100 g, followed by dried peppermint and star anise. Nobody eats 100 g of cloves, so the researchers also ranked foods by realistic servings. On that list, coffee, tea, dark chocolate, berries, olives and nuts rise to the top, and in most Western diets coffee alone supplies the single largest share of daily polyphenols.

Food	Approximate polyphenols (mg per 100 g or 100 mL)	Main polyphenol type
Cocoa powder, unsweetened	3,400	Flavanols
Dark chocolate (70 percent or more)	1,600 to 1,700	Flavanols
Ground flaxseed	1,500	Lignans
Black elderberry	1,350	Anthocyanins
Blueberries, lowbush (wild)	800	Anthocyanins
Black olives	570	Hydroxytyrosol, oleuropein
Hazelnuts	495	Proanthocyanidins
Filter coffee	200 to 250	Chlorogenic acids
Green or black tea	100 to 130	Catechins, theaflavins
Red onion	170	Quercetin

Figures are averages from food composition databases; content varies with variety, ripeness, processing and storage. Two practical patterns stand out. Darker, more bitter and more astringent usually means more polyphenols. And processing subtracts: alkalized (Dutch-process) cocoa loses most of its flavanols, fruit juice loses the skins, and white flour loses the bran.

Polyphenols vs antioxidants: what the label gets wrong

For twenty years polyphenols were sold as antioxidants, substances that neutralize free radicals, the unstable molecules produced during normal metabolism that can damage cells. The story was tidy: free radicals cause aging and disease, polyphenols mop them up, so more polyphenols means less disease.

The science did not cooperate. Large randomized trials of antioxidant supplements such as beta-carotene and vitamin E, summarized on MedlinePlus, found no protection against heart disease or cancer, and in some groups found harm. Blood levels of polyphenols, as noted, are too low and too brief to act as meaningful free-radical scavengers in the way they do in a test tube.

Researchers now describe polyphenols as signaling molecules rather than chemical sponges. Their metabolites appear to switch on the body’s own protective enzymes, dial down inflammatory pathways and influence gene expression in the cells lining blood vessels and the gut. The effect is indirect, like adjusting a thermostat rather than opening a window.

This distinction has consequences for shoppers. An ORAC score, a laboratory measure of antioxidant capacity that once appeared on packaging, tells you almost nothing about what happens after you swallow the food; the United States Department of Agriculture withdrew its ORAC database in 2012 for exactly that reason. A polyphenol count on an olive oil bottle is a more honest number, since it measures real compounds, but it still cannot predict how your particular gut will process them.

The practical upshot is reassuring. You do not need to chase the highest number. You need regular exposure to a range of plant foods, which is the same advice the NHS gives for its five-a-day guidance, arrived at from a different direction.

What the evidence actually says about polyphenols benefits

Nutrition evidence comes in grades, and polyphenol research spans all of them. Here is how it sorts out.

Strongest: randomized trials of whole dietary patterns. The PREDIMED trial in Spain randomized about 7,400 adults at high cardiovascular risk to a Mediterranean diet supplemented with either extra virgin olive oil or nuts, or to a lower-fat control diet. Over roughly five years, the Mediterranean groups had about 30 percent fewer major cardiovascular events. Polyphenols were one component of that diet among many, so the trial supports the pattern, not the compound. Mayo Clinic’s summary of the Mediterranean diet reflects this evidence base.

Moderate: randomized trials of single foods measuring intermediate markers. Dozens of trials lasting four to twelve weeks show that cocoa flavanols, berries, green tea and olive oil can lower blood pressure by a few points, improve how arteries dilate, and nudge cholesterol and blood sugar markers. These are real, reproducible, and small. They do not prove fewer heart attacks.

Moderate but mixed: trials of extracts on hard outcomes. COSMOS is the largest, and its main result was null, with a possible reduction in cardiovascular deaths that the investigators themselves called hypothesis-generating.

Weaker: observational studies. Large cohorts repeatedly find that people who eat the most flavonoid-rich foods have lower rates of heart disease, type 2 diabetes and cognitive decline. These people also tend to smoke less, exercise more and earn more, and statistics can only partly correct for that.

Weakest: laboratory and animal studies, which generate most of the dramatic headlines about cancer, longevity and brain repair. They are essential for understanding mechanisms and nearly useless for predicting what a food will do in a human.

Do polyphenols protect the heart?

Cardiovascular health is where the polyphenol evidence is deepest, and it is worth separating what is well established from what is hoped.

Well established: polyphenol-rich foods support the endothelium, the single layer of cells lining blood vessels that releases nitric oxide to help arteries relax. Cocoa flavanols are the best studied, with dozens of controlled trials showing improved flow-mediated dilation, a standard ultrasound measure of arterial flexibility, within hours to weeks. Blood pressure reductions in the range of two to four points systolic appear consistently across cocoa, tea and berry trials.

Reasonably supported: olive oil polyphenols such as hydroxytyrosol reduce the oxidation of LDL cholesterol, the chemical change that makes cholesterol more likely to lodge in artery walls. This is the basis of the European health claim, and it has held up in human trials, though the long-term clinical payoff is inferred rather than proven.

Suggestive: cohort data from the United States and Europe link higher flavonoid intake to roughly 10 to 20 percent lower rates of cardiovascular death. The American Heart Association’s dietary guidance emphasizes fruits, vegetables, whole grains, nuts and olive oil for heart health, which is a polyphenol-rich pattern even though the guidance is built on overall diet quality rather than any single compound.

Unproven: that a polyphenol supplement can substitute for those foods. COSMOS tested this directly in a well-designed trial and did not find a clear benefit on overall cardiovascular events.

For a reader with high blood pressure or high cholesterol, the message is simple. Polyphenol-rich foods belong in the plan your clinician recommends. They do not replace any part of it, and they should never be a reason to delay or adjust prescribed medicine.

Polyphenols and brain health: what trials show

Brain health is where enthusiasm most often outruns data, so it helps to be precise.

Observational cohorts are consistent. In the Nurses’ Health Study and similar groups, people who ate the most flavonoid-rich foods, particularly berries, had slower measured cognitive decline over decades, equivalent in some analyses to being a few years younger in brain age. The usual caveats apply: berry eaters differ from non-eaters in many ways.

Small trials are encouraging but short. Studies of blueberry, strawberry or cocoa flavanol intake lasting eight to twenty-four weeks in older adults have reported better performance on specific memory and attention tasks, and imaging studies show increased blood flow to the hippocampus, a brain region central to memory. The groups are small, often fewer than 100 people, and the tests are sensitive laboratory measures rather than everyday function.

The largest trial was less kind. COSMOS-Mind, which assessed cognition in more than 2,000 participants of the main COSMOS trial, found no benefit from the cocoa extract on a global cognitive score after three years. Interestingly, the same study found a modest benefit from the multivitamin arm, a result the investigators did not predict.

Mechanistically, the gut connection is relevant here too. Some polyphenol metabolites cross the blood-brain barrier, the protective filter between blood and brain tissue, and animal studies show they reduce inflammation in brain immune cells. Whether that translates to protection against dementia in people is unknown.

A fair summary: eating berries, cocoa and tea regularly is consistent with the diets associated with sharper aging, and there is no downside. Treating them as a defense against dementia is not supported by trial evidence, and anyone noticing real memory change needs an evaluation, not a grocery list.

Is apple cider vinegar a polyphenol?

No. Apple cider vinegar is mostly water and acetic acid, the compound that gives vinegar its sharpness. It does contain small amounts of polyphenols carried over from apples, mainly chlorogenic acid and some catechins, and unfiltered versions with the cloudy sediment known as the mother carry a little more. But a tablespoon delivers a fraction of what a single apple provides, and a tiny fraction of a cup of coffee.

The confusion arises because apple cider vinegar has its own wellness reputation, and online claims often borrow the language of polyphenol research to support it. The two bodies of evidence are different and should be kept apart.

What the vinegar research actually shows is thin. A handful of small, short trials suggest that taking vinegar with a carbohydrate-rich meal can blunt the rise in blood sugar afterward, probably by slowing stomach emptying. Trials on weight loss are few, small and inconsistent. No reputable trial has shown apple cider vinegar to control diabetes, lower cholesterol meaningfully, or alter the microbiome in a way that matters clinically.

There is a practical caution, too. Vinegar is acidic enough to erode tooth enamel with regular undiluted use, and it can irritate the esophagus. People taking medicines that lower potassium or blood sugar should talk with their prescriber before adding it routinely, because case reports describe interactions.

If you enjoy the taste, use it as a dressing with olive oil and a few herbs, which is where it belongs: a flavor that makes polyphenol-rich salads more appealing, not a polyphenol source in its own right. The nutritional credit goes to the apple, not to what the apple became.

Polyphenol supplements versus polyphenol rich foods

Walk into any pharmacy and you can find resveratrol, quercetin, green tea extract, grape seed extract and curcumin capsules, each promising the benefits of a diet without the diet. The evidence does not support the trade.

Food wins on three fronts. First, dose and form. In foods, polyphenols arrive in modest amounts, alongside fiber, vitamins and other compounds that affect how they are processed. In capsules, a single compound arrives in concentrations the body never meets in nature, and the gut bacteria that normally transform it may be overwhelmed or bypassed.

Second, evidence. Trials of whole foods and dietary patterns show consistent, if modest, benefits. Trials of isolated extracts are mixed at best. Resveratrol, the darling of the 2000s, has failed to show meaningful benefit in human trials despite striking results in yeast and mice. Curcumin is so poorly absorbed that much of the published work measures effects the compound cannot physically have reached. COSMOS, the largest extract trial, was null on its main outcome.

Third, safety. Concentrated green tea extract has been associated with liver injury in rare cases, which the National Center for Complementary and Integrative Health notes is not a concern with brewed tea. High-dose quercetin has been linked to kidney concerns in isolated reports. Supplements in the United States are not required to prove safety or effectiveness before sale, and independent testing has repeatedly found that labeled contents do not match what is in the bottle.

None of this means every supplement is dangerous. It means the burden of proof sits with the capsule, and so far the capsule has not met it. Anyone considering one, particularly while taking prescription medicines or during cancer treatment, should raise it with their clinician first.

What are the negative side effects of polyphenols?

From food, the side effects of polyphenols are few and mostly a matter of timing and quantity. From concentrated supplements, the list is longer.

Iron absorption is the best-documented issue. Polyphenols in tea and coffee bind to non-heme iron, the form found in plants and fortified foods, and can reduce its absorption by a large margin when consumed with a meal. For most people this is irrelevant. For someone with iron deficiency, a heavy menstrual cycle, a vegetarian or vegan diet, or a pregnancy, it is worth drinking tea and coffee between meals rather than with them.

Digestive effects can occur with sudden large increases in polyphenol-rich foods, particularly high-fiber ones such as berries, legumes and whole grains. Bloating and loose stools usually settle within a couple of weeks as the microbiome adjusts.

Caffeine is a companion issue. Coffee and tea deliver polyphenols with a stimulant that can disturb sleep, raise heart rate and worsen reflux in sensitive people. Decaffeinated versions retain most of their polyphenols.

Medicine interactions deserve attention. Green tea catechins can reduce the absorption of some blood pressure and cholesterol medicines by interfering with transporter proteins in the gut. High intakes of certain polyphenols may affect how the liver processes drugs, including blood thinners. Oncologists often ask patients to avoid concentrated antioxidant supplements during chemotherapy or radiation, because of a theoretical concern that they could blunt treatment. These are reasons to tell your clinician what you take, not reasons to fear a cup of tea.

Liver injury from green tea extract, kidney reports with high-dose quercetin, and unpredictable contents in unregulated products round out the supplement-specific concerns described in the previous section.

Common myths about polyphenols, corrected

The current wave of interest has carried some persistent errors with it.

Myth: more is always better. The evidence shows benefits accumulating with regular, moderate intake across many foods, with no sign that extreme amounts add anything and clear signs that concentrated extracts can cause harm. A diet built around three cups of coffee, a square of dark chocolate and a handful of berries is already polyphenol-rich.

Myth: red wine is a health food. Resveratrol made headlines, but the amount in a glass of wine is tiny, and the alcohol that comes with it carries well-documented risks. The World Health Organization states that no level of alcohol consumption is free of health risk. The polyphenols in grapes are available in the grapes.

Myth: the polyphenol count on olive oil is a health score. It is a chemistry measurement that reflects olive variety, harvest timing and freshness. Higher numbers generally mean fresher, more bitter oil, which is pleasant to know. They do not tell you how much benefit you will receive, which depends on your whole diet and your gut bacteria.

Myth: polyphenols detox the body. Your liver and kidneys handle that job. Polyphenol metabolites may support some of the enzymes involved, but no food or supplement flushes toxins.

Myth: cooking destroys polyphenols. Some, such as anthocyanins, are heat-sensitive, but others become more available when cooked. Tomatoes release more of their phenolic compounds when heated, and brewing is itself a form of extraction.

Myth: supplements and food are interchangeable. The largest trial to test this, COSMOS, found that a cocoa extract did not deliver the clear benefits that observational studies of cocoa-eating populations had suggested.

How to eat more polyphenols without overthinking it

If you remember one principle, make it this: color, bitterness and variety across the week.

Morning is already covered for most people. Coffee and tea are the leading sources in Western diets, and the polyphenols survive decaffeination. Adding a spoon of ground flaxseed or a handful of berries to oats, yogurt or a smoothie raises the count substantially; frozen berries are picked ripe and retain their anthocyanins well.

At lunch and dinner, the Mediterranean habit of finishing vegetables, beans and salads with extra virgin olive oil is the single most evidence-backed move, because it mirrors what the PREDIMED trial actually tested. Olives, capers, red onions and plenty of dried herbs such as oregano, thyme and rosemary are inexpensive ways to add more.

Snacks and dessert can carry weight too. A square or two of dark chocolate with 70 percent cocoa or more, a handful of hazelnuts, pecans or walnuts, an apple eaten with the skin, a few dried plums or dates: each delivers meaningful polyphenols along with fiber.

A few preparation details change the math. Keep skins on fruit and vegetables where you can. Choose whole grains over refined. Prefer natural cocoa over Dutch-process when baking. Let tea steep for several minutes. Eat the whole fruit rather than drinking the juice.

Timing matters only for iron. If you rely on plant sources of iron or have been told your iron is low, enjoy tea and coffee an hour or so away from meals.

Finally, let your microbiome adjust. If your diet has been low in plant foods, add new ones over a few weeks rather than all at once. Bloating at the start is common and usually temporary. The goal is a pattern you can sustain for years, because that is the timescale over which the evidence shows polyphenols earning their reputation.

When to see a doctor

Polyphenol-rich foods are safe for nearly everyone, and nothing in this article is a reason to change a prescribed medicine or delay care. There are situations where a conversation with your clinician comes first.

Talk with your doctor before starting any polyphenol supplement or extract if you take blood thinners, blood pressure or cholesterol medicines, diabetes medicines, or are undergoing treatment for cancer. Interactions are plausible and your prescriber can weigh them against your specific regimen. The decision about any supplement belongs to the clinician who knows your history, not to a label or a video.

Seek care promptly if you develop any of these after taking a concentrated supplement, particularly green tea extract:

• Yellowing of the skin or the whites of the eyes, dark urine, pale stools, or pain in the upper right abdomen, which can signal liver injury
• Marked fatigue, nausea or loss of appetite that persists for more than a few days
• Reduced urine output or swelling of the ankles
• Unusual bruising or bleeding, especially if you take an anticoagulant

Ask for a check-up if symptoms you were hoping to improve with diet are getting worse or are new: ongoing fatigue, dizziness, shortness of breath, chest discomfort, persistent digestive change, or noticeable memory decline. These need evaluation, and a diet, however good, is not a substitute for finding out why.

If you have iron deficiency, are pregnant, or follow a vegetarian or vegan diet, mention your tea and coffee habits at your next appointment so iron status can be monitored appropriately.

Children, people with kidney or liver disease, and anyone with a history of eating disorders should also discuss significant dietary changes with a clinician or registered dietitian rather than following an online protocol.

Frequently asked questions

What are polyphenols and why do they matter for gut health?

Polyphenols are protective compounds plants make, found in coffee, tea, berries, cocoa, olives, herbs and nuts. They matter for gut health because most reach the colon unabsorbed, where they suppress inflammation-linked bacteria, encourage beneficial groups such as Akkermansia and Bifidobacteria, and are converted into smaller molecules the body absorbs more easily. The relationship runs both ways: your bacteria determine how much benefit you get.

What food is highest in polyphenols?

Cloves are the richest source by weight, at roughly 15,000 mg per 100 g, followed by dried peppermint, star anise and unsweetened cocoa powder. Because nobody eats spices in quantity, the practical leaders are coffee, tea, dark chocolate, berries, olives, flaxseed and nuts. Darker, more bitter and more astringent foods generally contain more, and whole foods with skins beat juices and refined versions.

What are the main polyphenols benefits backed by evidence?

The best-supported benefits are small reductions in blood pressure and improved flexibility of blood vessels, shown in randomized trials of cocoa, tea, berries and olive oil lasting several weeks. The Mediterranean diet, rich in polyphenols, reduced major cardiovascular events by about 30 percent in the PREDIMED trial. Brain and cancer benefits rest mainly on observational and laboratory data and remain unproven.

What are the negative side effects of polyphenols?

From food, side effects are minor: reduced iron absorption when tea or coffee is taken with meals, temporary bloating when plant intake rises quickly, and caffeine effects from coffee and tea. Concentrated supplements carry more risk, including rare liver injury with green tea extract and possible interactions with blood thinners, blood pressure, cholesterol and cancer medicines. Discuss any supplement with your clinician.

What will polyphenols do to your body?

Most polyphenols pass through to the colon, where bacteria break them into metabolites that enter the bloodstream and act as signaling molecules. Over weeks of regular intake, these appear to calm inflammatory pathways, help arteries relax and support glucose handling. The effects are modest, comparable to those of regular exercise on blood pressure, and build gradually across many foods rather than from one.

Is apple cider vinegar a polyphenol?

No. Apple cider vinegar is mostly water and acetic acid, with only trace polyphenols left over from the apples. A tablespoon provides a tiny fraction of what one apple or one cup of coffee supplies. Small trials suggest vinegar with meals may blunt blood sugar rises, but it is not a meaningful polyphenol source, and undiluted use can erode tooth enamel.

Are polyphenol supplements as good as polyphenol rich foods?

Current evidence says no. Whole foods and dietary patterns show consistent modest benefits in trials, while isolated extracts have produced mixed or null results, including the large COSMOS cocoa trial. Supplements also deliver concentrations the body never meets in nature, bypass the gut bacteria that normally process polyphenols, and in some cases carry safety concerns. Speak with your clinician before taking one.

Does cooking destroy polyphenols?

Some do break down with heat, particularly the anthocyanins in berries, but many survive and a few become more available. Heating tomatoes increases the release of their phenolic compounds, brewing extracts polyphenols from coffee and tea, and dried herbs retain high levels. Steaming and brief cooking preserve more than long boiling, and the water used in boiling carries some polyphenols away.

How long does it take for polyphenols to work?

Blood levels of polyphenol metabolites peak within a few hours of eating and fall within a day, so single servings have no lasting effect. Trials measuring blood pressure and blood vessel function typically report changes after four to twelve weeks of daily intake. The population-level benefits seen in cohort studies reflect dietary habits sustained over years rather than short bursts.

Can I get enough polyphenols from coffee and tea alone?

Coffee and tea supply the largest share of polyphenols in many diets, but they offer a narrow range of types, mainly chlorogenic acids and catechins. Different gut bacteria process different polyphenols, so variety matters. Adding berries, cocoa, olive oil, nuts, legumes, whole grains and herbs broadens the mix and brings fiber and other nutrients that coffee and tea do not.

References

• MedlinePlus: Antioxidants
• NIH National Center for Complementary and Integrative Health: Green Tea
• NHS: Why 5 A Day?

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.