Longevity Briefs: Is A Flavonoid-Rich Diet Associated With Slower Ageing?

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Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: Flavonoids are plant-derived compounds with antioxidant and anti-inflammatory properties. Some studies suggest that a diet rich in flavonoids can delay the ageing process. How can scientists measure this? There’s no definitive way to measure how quickly someone is ageing, but researchers usually try to estimate biological age by measuring biomarkers of ageing.

Biological age is the body’s functional age, as opposed to chronological age (the number of years since a person was born). A biological age of 30 means the body operates like that of an average 30 year-old. Biomarkers of ageing are measurable factors like inflammatory factors in the blood that correlate with the progression of ageing. By comparing a person’s biomarkers of ageing to the population average, scientists can estimate their biological age. If a 50 year-old has the biomarkers that would be expected of the average 40 year-old, we might say that they had a biological age of 40.

What did the researchers do: In this study, researchers studied the relationship between flavonoid consumption and biological age using data from the National Health and Nutrition Examination Survey and the Food and Nutrient Database for Dietary Studies. They looked at data from 3,193 study participants who described their diets in a 24-dietary recall interview, and estimated their flavonoid intake. They then calculated their biological age based on multiple biomarkers of ageing including blood pressure, fasting glucose, fasting cholesterol levels, and fasting triglycerides.

Not all organs age at the same rate, so biological age was estimated separately for the cardiovascular system, kidneys, liver and whole body. Researchers then calculated the difference between the participants’ biological age and their chronological age, or ∆age. For example, a liver with a ∆age of 5 is biologically 5 years older than its chronological age, while a ∆age of -5 means that it is biologically 5 years younger than its chronological age.

The researchers attempted to adjust for confounding factors such as diet, smoking status and obesity.

Key takeaway(s) from this research:

• Increased flavonoid intake was significantly associated with lower ∆age, although this did not apply to the kidneys and was not found in smokers or moderate to heavy drinkers
• The liver appeared to benefit most from increased flavonoid intake
• Anthocyanidins, isoflavones and flavones were associated with the largest benefits

The third of participants with the highest flavonoid intake were significantly more likely to have a negative whole body ∆age (meaning biological age was lower than chronological age) and across multiple organ systems unless they smoked, were moderate to heavy drinkers, or were under the age of 30. The third of participants with the lowest intake had a positive ∆age on average, while the middle third with moderate intake derived some benefit but not as much as those with the highest intake.

The largest association was for liver ∆age: moderate intake was associated with a liver ∆age of -4.15 years on average, while the highest intake was associated with a ∆age of -4.69 years. On average, the highest intake was associated with a ∆age of -1.68 for the heart and -1.1 for the whole body. There was no significant effect on the kidneys for any flavonoid intake. The three flavonoid subclasses with the most pronounced effects on ∆age were anthocyanidins, isoflavones and flavones.

Researchers identified multiple confounding factors – for example, people who consumed fewer flavonoids were more likely to be diabetic, a condition that results in higher measured biological age. While researchers tried to control for such factors, they did not control for all of them – for example, they didn’t account for any dietary supplements or medications that participants may have been taking. Also, since flavonoid intake wasn’t measured directly but estimated based on self-reported dietary habits, there will be inherent inaccuracies and biases that can’t be accounted for.

How can we apply this knowledge today:

Overall, this research adds to the existing evidence that flavonoid intake correlates with slower biological ageing, but can’t prove causation. Still, you’re not going to lose out from consuming more flavonoid-containing foods, since they’re all pretty healthy in other ways.

Flavonoid subclass	Sources
Anthocyanidins	Berries, currants, grapes, black elderberries, aronia berries (chokeberries), black plums, blood oranges, cherries, black and red grapes, pomegranates, red cabbage, red onions, red radishes, purple cauliflower, purple corn, skin of purple aubergine, black beans, and black rice
Isoflavones	Soy and its products, legume seeds (lentils, beans, peas), soybeans, tofu, miso, tempeh, chickpeas, and peanuts
Flavones	Tea, wine, leafy vegetables, onions, apples, berries, cherries, soybeans, and citrus fruits