Eating Your Five Servings a Day May Not Deliver the Flavanols Your Heart Needs

What a sobering new study tells us, and four practical ways to get more out of the produce you already eat

For years, the advice has been simple and reassuring: eat your fruits and vegetables, hit your five-a-day, and your heart will thank you. It is good advice, and nothing in this article changes that. But a careful new study published in Food & Function in 2026 delivers a humbling message for those of us who care about the specific compounds inside our food. Even people who faithfully follow dietary guidelines, eat their produce, and score well on diet-quality measures mostly fail to reach the level of one particular family of heart-protective compounds that the science now points to. As is so often the case, the design is wiser than our assumptions, and there is more for us to learn.

The compounds in question are flavanols, a group of plant-derived polyphenols found in fruits, vegetables, tea, and cocoa. They matter because of COSMOS, the largest randomized controlled trial of polyphenols ever conducted. In that study, a daily intake of 500 mg of flavanols reduced cardiovascular disease mortality by 27%, total cardiovascular events by 15%, and major cardiovascular events by 16% in older adults. That is not a trivial signal. It is the kind of result that makes you want to be sure you are actually getting the dose.

What the study actually did

The researchers asked a deceptively simple question: if you follow the dietary guidelines we already have, do you naturally reach that protective 500 mg per day of flavanols? If the answer were yes, there would be little reason to create separate flavanol recommendations. So they looked at two large, geographically distinct groups: 6,509 US adults from the COSMOS trial and 24,154 UK adults from the EPIC-Norfolk study.

Crucially, they did not rely on what people remembered eating. Food-frequency questionnaires and diet diaries are notoriously unreliable for estimating intake of specific compounds. Instead, they measured flavanol intake objectively using two validated urinary biomarkers, gVLMB and SREMB, that reflect how much flavanol the body has actually absorbed. This is the part worth pausing on. Self-reported diet is a guess; a biomarker in the urine is a measurement. The study rests on measurement.

They then sorted participants by how much fruit and vegetables they ate and by overall diet quality, and asked how many in each group actually hit the 500 mg per day mark.

The sobering result

Higher fruit and vegetable intake and better diet quality were indeed associated with higher flavanol intake, which is encouraging as far as it goes. But the magnitude was small, and the ceiling was low. Among participants who met dietary guidelines, fewer than 25% reached an estimated flavanol intake of at least 500 mg per day. Across the entire COSMOS group, only 19.2% met that threshold; in EPIC-Norfolk, 17.9%.

Even among the people doing everything right, the top quartile of fruit and vegetable consumers, only about 21% hit the target. That is barely higher than the 19.2% seen in the cohort as a whole. In the UK study, the relationship was even more counterintuitive: participants with the best adherence to dietary guidelines were among the least likely to consume 500 mg per day of flavanols, largely because tea, not produce, was driving flavanol intake in that population, and the guideline-adherent were not necessarily the heaviest tea drinkers.

The researchers went further and ran 10,000 computer simulations of people eating typical American fruits and vegetables, things like bananas, apples, tomatoes, grapes, oranges, and carrots. Eating five portions of these common items rarely gets anyone near 500 mg per day. Even deliberately choosing the highest-flavanol produce pushed the probability up but kept it below 50%. And the authors were honest that their thresholds were deliberately generous, designed to overestimate how many people qualified. In other words, the real picture is probably worse than these numbers suggest.

The takeaway is not that fruits and vegetables fail us. They remain foundational to health for dozens of reasons unrelated to flavanols. The takeaway is narrower and more useful: if your goal is the specific flavanol dose shown to protect the heart in COSMOS, simply eating more produce, as currently advised, is unlikely to get you there on its own.

So what can we actually do?

Here is where a sobering study becomes practical. If guideline-level produce intake falls short, there are sensible, evidence-aligned ways to close the gap. I want to offer two strategies for getting more flavanols into your diet, and two for getting more of what you eat across the gut wall and into your bloodstream. None of these requires a supplement or a prescription. There are changes to how much, what kind, and how you prepare the food already on your plate.

Two ways to increase your flavanol intake

1. Eat more servings of fruits and vegetables

This sounds almost too obvious after everything above, but the study’s own data make the case more precisely than slogans do. Five portions are not enough to reliably reach 500 mg per day, but simulations showed that the probability of meeting the target increased steadily as the number of portions rose. The relationship is real; it is just that the recommended five servings sit too low on the curve. Pushing from five toward eight, ten, or more daily portions, especially when those extra portions are chosen for their flavanol density, meaningfully raises your odds.

Where do the flavanols concentrate? In pome fruits like apples and pears, in berries, in stone fruits, in beans such as pinto, kidney, and fava, and in cocoa and black tea. Among culinary plants, the herbs and spices richest in flavonols are capers, dill, cilantro/coriander leaf, chives, fennel leaves, and parsley, with capers being the single most concentrated known food source. Building more of these into your day, rather than simply eating more of whatever is convenient, is the difference between climbing the curve and staying flat on it. The point is not to abandon variety, which carries its own benefits, but to add volume and to weight that added volume toward the richest sources.

2. Choose organic whenever possible

There is a reasonable, if not airtight, case that organically grown produce carries more polyphenols. Comparative studies, including work on plant foods grown under organic versus conventional systems in Spain, have found that organic samples tend to have higher total phenolic content and greater antioxidant capacity. A broader review reaches a similar conclusion across many crops.

The proposed mechanism is elegant. Plants make polyphenols partly as a defense response. Grown with fewer synthetic inputs and under more pest pressure, organic plants experience more stress, and that stress can stimulate them to produce more of these protective secondary metabolites. The same compounds that help the plant survive may also help us. The effect is not enormous and varies by crop, soil, and management, so think of organic as a modest multiplier on top of the produce you are already choosing, not a magic bullet. But when the choice is available and affordable, it tilts the odds in your favor.

Three ways to increase bioavailability

Increasing the amount of flavanols you eat is only half the equation. The other half is how much your body can actually liberate from the plant and absorb. Polyphenols face two bottlenecks. First, they are often locked inside plant cell walls and membranes, and if those structures stay intact through digestion, much of the cargo passes through unused. Second, many flavanols arrive bound to sugars in forms the body absorbs poorly until that sugar is cleaved off. The first two strategies below address the physical bottleneck by breaking down cell structures before or during eating; the third addresses the chemical bottleneck by enlisting gut bacteria to unlock the sugar-bound forms. Here, the supporting evidence is largely mechanistic and review-level rather than drawn from large human trials, so I hold it a little more loosely, but it is consistent and biologically sensible.

1. Eat frozen fruits and vegetables

Freezing has an underappreciated advantage. As water inside plant cells freezes, it forms ice crystals that physically rupture cell walls and membranes. When the food later thaws and is digested, those broken structures release their phenolic contents more readily. Reviews of non-thermal processing describe exactly this: freezing helps preserve polyphenols and, through cell disruption, can increase the release of bound phenolics during digestion.

There is a caveat worth respecting. Freezing itself tends to preserve polyphenols well, but very long frozen storage and harsh thawing can cause losses due to oxidation and enzymatic activity. So the practical advice is to use frozen produce that has not languished in the freezer for a year, and to avoid aggressive thawing. Frozen berries blended straight from the bag, for instance, capture the benefit while sidestepping the downside. As a bonus, frozen produce is often picked and frozen at peak ripeness, which is a quiet advantage in itself.

2. Drink some of your produce as blended smoothies

Blending is, in effect, mechanical demolition of plant cell walls, and that is precisely why it helps. High-speed blending breaks cells open and reduces particle size, both of which increase the fraction of polyphenols released during digestion. Multiple reviews of food processing make this point directly: grinding, pureeing, juicing, and blending raise polyphenol bioavailability by rupturing cell structures and exposing their contents to digestive enzymes and the gut microbiome.

A note on what you blend, and how: One oxidation problem deserves special mention, because it can quietly undo the very benefit you are chasing. Flavanols are vulnerable to an enzyme called polyphenol oxidase, or PPO, the same enzyme that turns a cut apple brown. PPO needs oxygen to work, and when it does, it converts flavanols into compounds the body cannot use. The catch is that some fruits are far richer in PPO than others, and bananas are the worst offenders. In a controlled crossover study, adding banana to a flavanol-rich smoothie cut the level of flavanols circulating in the blood by 84% compared with a flavanol supplement, and the banana’s PPO had already degraded nearly a third of the flavanols in the glass before anyone took a sip. The practical lesson is simple: do not blend bananas or other high-PPO produce, like beet greens, with your berries, cocoa, or green tea. Pair your flavanol-rich ingredients with low-PPO fruits instead, drink the smoothie promptly, and consider a squeeze of lemon or lime, since the citric acid and vitamin C both help blunt PPO. There is also a plausible case, though not yet proven, that a vacuum blender helps because it removes most of the oxygen from the blending chamber before the blades start, and less oxygen means less oxidation driven by PPO and ordinary air exposure. One small study found that vacuum blending removed most of the dissolved oxygen and slowed the loss of polyphenols and antioxidant capacity in apple and blueberry juice. I mention it as a reasonable option rather than a requirement, since that study looked at total polyphenols rather than flavanols specifically. The evidence base remains thin, but the underlying chemistry is sound, and the practice costs little to invest in with a vacuum blender (click here).

3. Add fermented foods to feed and partner with your gut

There is a final, often overlooked lever, and it works from the inside. Many flavanols arrive in our food bound to sugars as glycosides, and in that form, they are poorly absorbed. The body has to cleave off the sugar, releasing the free flavanol, or aglycone, which crosses the small-intestinal wall far more efficiently. Human studies in ileostomy patients showed decades ago that quercetin glucosides are almost completely hydrolyzed and absorbed high in the gut, with roughly 65-80% taken up once the sugar is removed. Some of that cleaving is done by our own intestinal enzymes, but a meaningful share, especially for sugar-bound forms that slip past those enzymes, depends on the bacteria living in our gut. This is where fermented foods earn their place. A 2026 review in Frontiers in Nutrition describes how microbial enzymes, the glycosidases, esterases, and decarboxylases produced by bacteria such as Lactobacillus and Bifidobacterium, restructure flavonoids during fermentation into metabolites with greater solubility, stability, and absorbability. A companion review in Nutrients makes the same point from the other direction, noting that the bioaccessibility of flavonoids is shaped significantly by their interactions with these probiotic species. The practical implication is modest but real: regularly eating fermented foods that carry these strains, such as yogurt, kefir, kimchi, and sauerkraut, helps cultivate a microbial community better equipped to unlock the flavanols in the produce you are already eating. As with the strategies above, I hold this loosely, since the human evidence is still largely mechanistic, but it is biologically sound and costs nothing to adopt.

A frozen-berry smoothie is almost a perfect storm of the strategies in this article working together: more servings in one glass, organic if you choose, frozen for cell rupture, and blended for further disruption. Stir in a spoonful of kefir or plain yogurt, and you add the final piece, partnering with the gut bacteria that help unlock the sugar-bound flavanols, so that every bioavailability strategy in this article comes together in a single glass. I would offer one note of moderation, not as a rule but as common sense. Blending whole fruit keeps the fiber, which juicing discards, so favor smoothies over juices, and be mindful that liquid calories are easy to overdo. Used thoughtfully, a daily smoothie is one of the simplest ways to increase both the amount and the availability of the flavanols you consume.

A closing word

There is something clarifying about a study like this. It does not tear down the advice we have always given; it refines it. Fruits and vegetables remain essential, and no one should walk away eating less produce. What the data ask of us is a little more intention: more servings, weighted toward the richest sources, choosing organic where we can, preparing in ways that free the compounds inside, and pairing with the fermented foods that help our gut unlock them. These are small, achievable shifts. Taken together, they move us meaningfully closer to the level of flavanols the heart appears to need.

We were given bodies of remarkable design and a creation full of foods that nourish them. Part of stewarding that gift well is staying humble enough to update our habits when better evidence arrives, and grateful enough to keep tending the one body we are each entrusted with. Eat well, prepare wisely, and be encouraged. The path to a stronger heart runs straight through the produce aisle, and now we know a little more about how to walk it.

References

Eating Your Five Servings a Day May Not Deliver the Flavanols Your Heart Needs

Dr. Daniel Thomas, DO, MS