Are berries and red wine the secret to living longer? If you’ve been keeping an eye on nutrition headlines this summer, you might have heard that a fountain of youth could be hiding in your produce aisle or liquor store.
Yes, it seems that every so often, a study comes out linking [insert food item] to [insert health outcome], and the press predictably latches on to the findings to generate clickbait headlines that we’d all love to believe. The impetus for this recent iteration of the pattern? A research article on associations between consumption of flavonoids — i.e., biologically active compounds found in plants — and various health outcomes.
While it can be very tempting to jump on board with any results suggesting that we can improve our health with delicious foods we already enjoy eating, wanting something to be true unfortunately doesn’t make it so. We must be very careful to examine the data with a critical eye and decide for ourselves what conclusions we can really make — rather than falling for punchy, too-good-to-be-true headlines.
Are flavonoids a fountain of youth?
Flavonoids are naturally occurring compounds found in plants — think the anthocyanins that make berries blue, the catechins in your green tea, or the quercetin in red wine. There are six main types of flavonoids covering a range of potential benefits, including antioxidant effects, anti-inflammatory properties, hormone modulation, and more. Given these varied effects, researchers Parmenter et al. asked an intuitive question: if different flavonoids can have different benefits for the body, do individuals who consume a diverse array of these compounds tend to experience broader protection and better health than those who consume fewer flavonoid types?
To test this, they turned to UK Biobank data from over 120,000 individuals (ages 40–69 years) with no cardiovascular disease (CVD), type 2 diabetes (T2D), cancer, respiratory disease, or neurodegenerative disease at baseline. Participants completed 24-hour dietary questionnaires on 2–5 occasions, from which the investigators calculated flavonoid diversity scores (covering a total of 31 unique flavonoid compounds) by grouping plant-derived foods and beverages according to flavonoid content. The researchers then followed participants for about a decade (median follow-up of 8.7–10.6 years, depending on the specific outcome) to assess incidence of chronic diseases and all-cause mortality (ACM).
After controlling for confounding factors like exercise, smoking, BMI, education, and socioeconomic status, they reported that higher flavonoid diversity correlated with a striking pattern of risk reduction across several health outcomes. When normalizing for total flavonoid intake, participants in the highest quintile of diversity were found to have a 14% lower risk of ACM than participants in the lowest quintile (HR: 0.86; 95% CI: 0.78–0.95), and this lower mortality risk was reflected in risk analyses for specific chronic diseases. Those consuming the most diverse breadth of flavonoids also exhibited a 10% risk reduction for CVD (HR: 0.90; 95% CI: 0.82, 0.98), a 20% risk reduction for T2D (HR: 0.80; 95% CI: 0.70, 0.91), and an 8% risk reduction in both total cancer (HR: 0.92; 95% CI: 0.85, 0.99) and respiratory disease (HR: 0.92; 95% CI: 0.86, 0.98).
Sounds great — let’s all break out some red wine to celebrate and toast to our health!
A marker of healthy lifestyle
Alas, now for the reality check, and it comes in the form of a familiar issue that often plagues nutritional epidemiology: healthy user bias.
Who are the people eating the most diverse array of flavonoid-rich foods? With various flavonoids present in various plants, it is the people who take health advice like “eating the rainbow” — a simple reminder to fill your plate with a variety of fruits and vegetables. By definition, these people are eating more micronutrient-rich, whole foods, which means they’re also probably consuming less calorie-dense ultraprocessed foods. And if they’re taking care to heed advice regarding fruits and vegetables, there’s a high probability that they’re adhering to other healthy habits, too, such as engaging in regular exercise or getting enough sleep.
This isn’t a leap, you can see it right in the study data. Those in the lowest flavonoid diversity group were more likely to smoke, less likely to exercise, and had higher BMIs — all characteristics of a generally unhealthy population. As such, those with the highest diversity scores weren’t just eating more colorful foods — they were living fundamentally different lives characterized by many healthy choices that could all contribute to lower risk of disease and mortality.
Unfortunately for Parmenter et al., this makes determining the individual impacts of various interventions (like flavonoid diversity) incredibly tricky. Sure, the researchers controlled for known confounders like exercise and smoking status, but there are countless other, unmeasured factors that cluster together in healthy lifestyles: stress management, sleep quality, preventive healthcare, social connections, and dozens of other behaviors that no statistical model can fully capture. It’s possible that flavonoids have nothing at all to do with the apparent health of the group in the highest flavonoid diversity quintile, and that the associations are due entirely to these other healthy-behavior covariates.
Indeed, if flavonoid diversity was truly a major driver of these health benefits, we’d expect to see a clear dose-response relationship — i.e., incrementally more diversity should lead to incrementally better outcomes. But that’s not what happened. Instead of a smooth progression, the results looked more like statistical noise. Benefits appeared and disappeared across different levels of intake without any coherent biological story. In some cases, increased flavonoid diversity even appeared to very slightly increase risk.
This erratic pattern is likely a combination of residual confounding that the statistical models couldn’t capture and the inherent inaccuracy of self-reported dietary data. When people fill out food questionnaires, they’re relying on memory, making estimations, and often telling researchers what they think they should be eating rather than what they actually consume. Layer this reporting bias on top of unmeasured lifestyle differences and the potential for dietary changes over time, and you get exactly the kind of messy, inconsistent results we see here — the signature of confounding and measurement error masquerading as a biological effect.
Creating hypotheses for further research
Still, none of the flaws in this study or its interpretations should be taken as evidence denying the possible health effects of flavonoids. There are plausible biological mechanisms by which these and other plant-derived compounds might benefit health, some of which are supported by experimental evidence. We’ve discussed a handful of such effects in past content on the flavonoids curcumin and epicatechin, for instance. I absolutely hope to see more thorough investigation of such compounds in the near future.
But what can we take from this particular study on flavonoid diversity? It demonstrates that people who eat diverse, plant-rich diets tend to be healthier overall — a fairly intuitive finding. Flavonoids might be contributing to that health benefit, or they might simply be passive bystanders — markers of a more general lifestyle pattern that promotes well-being through multiple pathways.
In other words, these data are best used for generating hypotheses for future rigorous experimentation, such as randomized controlled trials involving flavonoid supplements or carefully controlled diets. As with all observational research, the present study should not be interpreted as evidence of causation.
The bottom line
Despite what many of us might wish (and what headlines and social media might claim), the secret to longevity isn’t hiding in your wine glass or cup of tea. It’s in the comprehensive health-conscious choices that you make throughout your life — which might include a diet rich in flavonoids.
So by all means, eat your colorful fruits and vegetables. Enjoy that cup of tea or maybe even an occasional glass of red wine. But don’t expect them to be silver bullets for health while you neglect exercise, sleep, stress management, and all the other unsexy factors that actually drive long-term well-being. The real secret isn’t in any single nutrient or food — in fact, it’s no secret at all. It’s making tried-and-true choices for our health across the board, day after day, and seeing the accumulated effort gradually translate to a healthier life.
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References
- Parmenter BH, Thompson AS, Bondonno NP, et al. High diversity of dietary flavonoid intake is associated with a lower risk of all-cause mortality and major chronic diseases. Nat Food. 2025;6(7):668-680. doi:10.1038/s43016-025-01176-1
