Adhering to dietary guidelines does not yield flavanol intake levels associated with beneficial cardiovascular effects

This study demonstrates that adhering to current dietary guidelines for fruit and vegetable intake is insufficient to achieve the 500 mg/day flavanol intake level associated with cardiovascular benefits, suggesting that specific dietary reference values for flavanols may be necessary.

The Gist

The Big Question: "Is Eating 'Healthy' Enough?"

Imagine you are trying to fill a specific bucket with water. This bucket represents the amount of flavanols (a special plant chemical found in fruits, veggies, and tea) that scientists have proven is needed to give your heart a superpower boost.

According to a massive study called the COSMOS trial, you need to fill this bucket with 500 mg of flavanols every day to significantly lower your risk of heart disease.

The big question this new paper asks is: "If I just follow the standard advice to 'eat more fruits and vegetables,' will my bucket naturally fill up to that 500 mg level?"

The Experiment: Checking the Bucket with a "Magic Test"

Usually, when people ask, "How many apples did you eat?" they rely on your memory. But memory is like a leaky sieve; you forget things, or you guess wrong.

Instead of asking people what they ate, these researchers used a biomarker. Think of this as a magic urine test.

• When you eat flavanols, your body turns them into specific chemicals that show up in your urine.
• The researchers measured these chemicals in two huge groups of people:
  1. COSMOS: Over 6,500 older adults in the US.
  2. EPIC-Norfolk: Over 24,000 adults in the UK.

This was like checking the bucket directly to see how much water was actually inside, rather than asking the person how much they thought they poured in.

The Surprise Result: The Bucket is Mostly Empty

The researchers looked at the people who were doing everything "right." These were the folks who:

• Ate the recommended 5+ servings of fruits and veggies a day.
• Followed the "Alternative Healthy Eating Index" (a fancy score for a perfect diet).
• Even the people who drank a lot of tea (a major source of flavanols in the UK).

The Shocking Finding: Even among the "super-healthy" eaters, fewer than 25% had enough flavanols in their system to reach that magic 500 mg goal.

The Analogy: Imagine you are told to drive 60 miles per hour to get to work on time. You check your speedometer, and even though you are driving a brand new, high-performance car (a healthy diet), you are only going 30 mph. You are doing something right, but you aren't going fast enough to get the result you want.

Why Doesn't "Healthy Eating" Work Here?

The paper explains a few reasons why just eating "more" isn't the same as eating "enough" of this specific chemical:

1. The "Apple Lottery": Not all apples are created equal. One apple might have a tiny bit of flavanols, while another apple of the same type might have 10 times more, depending on the soil, the weather, and the specific breed. It's like buying a lottery ticket; you might get a winner, or you might get a dud. You can't guarantee a high flavanol intake just by picking a random fruit.
2. The "Flavor Trap": Some of the best sources of flavanols (like certain types of cocoa or bitter-tasting fruits) are also the ones that taste astringent or bitter. Farmers and food companies often breed fruits to be sweeter and less bitter, which accidentally strips away the very flavanols we need.
3. The Tea Gap: In the UK, people drink a lot of tea, which helps, but even there, it wasn't enough to fill the bucket for most people. In the US, tea consumption is much lower, making it even harder to reach the goal.

The Simulation: Trying to "Game" the System

The researchers ran computer simulations to see if they could "hack" the diet.

• Scenario A: Eat 5 random servings of common US fruits and veggies. Result: You almost never hit 500 mg.
• Scenario B: Eat 5 servings, but only pick the ones known to be high in flavanols. Result: You get closer, but you still only have a less-than-50% chance of hitting the target.

The Bottom Line: We Need a New Map

The authors conclude that following current dietary guidelines is not enough to get the heart-health benefits of flavanols.

Think of it like this:

• Current Guidelines: "Eat a balanced diet with lots of plants." (Good for general health, but misses the specific target).
• The New Need: We need a specific "Flavanol Target." Just like we have specific recommendations for Vitamin C or Calcium, we might need a specific recommendation for flavanols.

What does this mean for you?
You should still eat your fruits and veggies! They are great for you. But if you want to get that specific heart-protecting boost found in the COSMOS trial, simply eating "healthy" might not be enough. You might need to be more strategic—perhaps focusing on specific high-flavanol foods (like certain teas, cocoa, or specific berries) or waiting for food companies to breed varieties that are naturally richer in these heart-healthy compounds.

In short: The current map gets you to the right neighborhood, but it doesn't get you to the specific house you need to visit. We need a more detailed map.

Technical Summary

1. Problem Statement

While the COSMOS trial (Cocoa Supplement and Multivitamin Outcomes Study) established that an intake of 500 mg/day of flavanols significantly reduces cardiovascular disease (CVD) mortality and events, there is ongoing debate regarding whether specific dietary reference values (DRIs) for flavanols are necessary.

• The Hypothesis: Since fruits and vegetables are primary sources of flavanols and are heavily emphasized in current dietary guidelines (e.g., "5-a-day"), it was hypothesized that adherence to these general guidelines might naturally yield sufficient flavanol intake (≥500 mg/day) to confer cardiovascular benefits.
• The Gap: There is a lack of empirical data demonstrating whether following current fruit/vegetable recommendations actually results in flavanol intakes comparable to the therapeutic levels tested in the COSMOS trial. Furthermore, reliance on self-reported dietary assessments has historically been limited by inaccuracies in estimating flavanol content.

2. Methodology

The study utilized a multi-cohort approach combining objective biomarker data with dietary assessments and computational simulations.

• Study Populations:
  • COSMOS (USA): A post-hoc analysis of 6,509 participants from the COSMOS trial (US adults, aged ≥60/65) who provided spot urine samples during the run-in phase.
  • EPIC-Norfolk (UK): An observational cohort of 24,154 participants from the UK, providing spot urine samples and dietary data.
• Biomarkers (Objective Measurement):
  • Instead of relying solely on food frequency questionnaires (FFQ), the study measured urinary biomarkers to objectively estimate flavanol intake:
    • gVLMB: 5-(3',4'-dihydroxyphenyl)-γ-valerolactone metabolites (general flavanol intake).
    • SREMB: Structurally related (–)-epicatechin metabolites (specific to (–)-epicatechin).
  • Threshold: Participants were classified as meeting the 500 mg/day target if their urinary SREMB concentration was >7.77 µM OR gVLMB concentration was >18.21 µM.
• Dietary Assessments:
  • COSMOS: Semi-quantitative FFQ used to calculate fruit/vegetable servings and the Alternative Healthy Eating Index (aHEI) score.
  • EPIC-Norfolk: 7-day food diaries used to calculate grams of fruit/vegetables and plasma Vitamin C as a surrogate for diet quality.
• Statistical Analysis:
  • Logistic regression models adjusted for age, sex, and BMI to determine Odds Ratios (OR) of meeting the 500 mg/day threshold across quartiles of diet quality.
  • Monte Carlo Simulations: 10,000 simulations were run using Phenol-Explorer data and NHANES consumption patterns to model the probability of reaching 500 mg/day based on varying numbers of fruit/vegetable portions and selection strategies (random, weighted by US consumption, or weighted by high flavanol content).

3. Key Contributions

• Objective Validation: This is one of the first studies to use validated urinary biomarkers (gVLMB and SREMB) to objectively assess whether general dietary guidelines translate to specific bioactive intake levels, bypassing the limitations of self-reported dietary data.
• Cross-Geographical Replication: The findings were replicated in two distinct populations (US and UK) with different dietary patterns (e.g., higher tea consumption in the UK), strengthening the generalizability of the results.
• Simulation Modeling: The study introduced a simulation framework to demonstrate that even optimizing fruit/vegetable selection for high flavanol content does not guarantee reaching the 500 mg/day threshold.

4. Key Results

• Low Prevalence of Target Intake:
  • Only 19.2% of COSMOS participants and 17.9% of EPIC-Norfolk participants met the biomarker-estimated intake of ≥500 mg/day.
  • Crucially, even among participants in the top quartile of fruit/vegetable intake and diet quality (high aHEI scores), only 21% (COSMOS) and 16% (EPIC-Norfolk) achieved the 500 mg/day threshold.
• Weak Association with Diet Quality:
  • In COSMOS, higher aHEI scores were associated with a modest increase in the odds of meeting the threshold (OR 1.26), but the absolute percentage remained low.
  • In EPIC-Norfolk, higher fruit/vegetable intake was actually associated with a slightly lower odds of meeting the threshold (OR 0.99), likely due to the inverse relationship between high fruit/veg intake and tea intake (a major flavanol source in the UK).
• Simulation Findings:
  • Simulations showed that consuming 5 portions of fruits/vegetables (the standard guideline) selected at random or based on typical US consumption patterns yields a very low probability (<20%) of reaching 500 mg/day.
  • Even when selecting portions specifically weighted for high flavanol content, the probability of reaching 500 mg/day remained below 50%.
• Tea Consumption: While tea intake increased the odds of meeting the threshold (especially in the UK where tea consumption is high), even the highest tea consumers rarely reached the 500 mg/day target solely through tea.

5. Significance and Conclusion

• Guidelines are Insufficient: The study concludes that adherence to current dietary guidelines (focusing on fruit and vegetable quantity and general diet quality) does not yield flavanol intake levels comparable to those proven to reduce cardiovascular risk in the COSMOS trial.
• Need for Specific Recommendations: The authors argue that generic advice to "eat more fruits and vegetables" is insufficient for optimizing flavanol intake. They suggest that specific dietary reference values (DRIs) for flavanols may be necessary to achieve public health benefits.
• Agricultural Implications: The findings highlight the variability of flavanol content in produce (due to cultivar, climate, etc.) and suggest that specific recommendations could drive agricultural breeding programs to develop varieties with higher flavanol content.
• Future Directions: The paper calls for the development of quantitative targets for bioactives and suggests that food producers and policymakers should consider strategies to increase the flavanol density of the food supply rather than relying solely on increased volume consumption of current produce.

Caveat: As a preprint, this research has not yet undergone peer review, and the authors note that interindividual differences in bioavailability and sampling times can influence biomarker levels. However, the use of large cohorts and objective biomarkers provides robust evidence challenging the assumption that current dietary guidelines are sufficient for flavanol optimization.