Data from the Danish Diet, Cancer and Health cohort finds that those consuming 500 milligrams (mg) of total flavonoids a day had the lowest risk of a cancer or heart disease-related death.
Total flavonoid intake and its link to mortality rates appear stronger in smokers than in non-smokers, as well as in heavy versus low-moderate alcohol consumers.
“It's important to note that flavonoid consumption does not counteract all of the increased risk of death caused by smoking and high alcohol consumption,” says lead researcher Dr Nicola Bondonno. “By far the best thing to do for your health is to quit smoking and cut down on alcohol.”
"It's important to consume a variety of different flavonoid compounds found in different plant based food and drink,” adds Bondonno, a post-doctoral research fellow at Australia’s Edith Cowan University (ECU).
“This is easily achievable through the diet: one cup of tea, one apple, one orange, 100 grams (g) of blueberries, and 100g of broccoli would provide a wide range of flavonoid compounds and over 500mg of total flavonoids."
An estimated 7.8 million premature deaths worldwide in 2013 is attributable to a fruit and vegetable intake below 800 g/day.
While, flavonoids show anti-inflammatory effects and improvements to blood vessel function, emerging evidence suggests they may offer greater protection to those with harmful lifestyle habits.
Flavonoids may also protect against some of the detrimental effects that these factors have on nitric oxide bioavailability, endothelial function, blood pressure, inflammation, blood lipids, platelet function, and/or thrombosis.
In the prospective cohort study, researchers from ECU and Herlev & Gentofte University Hospital in Denmark followed 56,048 Danish participants for 23 years, recording 14,083 deaths.
Data analysis found a moderate habitual intake of flavonoids was inversely associated with all-cause, cardiovascular- and cancer-related mortality. This association appeared to plateau at intakes of around 500 mg/day.
In addition, the inverse associations between total flavonoid intake and mortality outcomes were considered stronger and linear in smokers than in non-smokers,
This observation was also true for heavy (more than 20 grmas per day (g/d)) versus low-moderate (less than 20 g/d) alcohol consumers.
“These findings are important as they highlight the potential to prevent cancer and heart disease by encouraging the consumption of flavonoid-rich foods, particularly in people at high risk of these chronic diseases," says Dr Bondonno.
"We know these kind of lifestyle changes can be very challenging, so encouraging flavonoid consumption might be a novel way to alleviate the increased risk, while also encouraging people to quit smoking and reduce their alcohol intake."
Gut microbiome influence?
Writing in the Nature Communications journal, the team think the findings could contribute to optimising dietary guidelines in those engaging in harmful dietary habits.
Here, the study’s observations could help ensure flavonoid intake is adequate considering these populations may benefit more from higher intakes.
Equally, the team point to the inverse association between flavonoid intake and mortality as usually weaker in obese participants.
The findings go against the team’s hypothesis that flavonoids would be more protective in obese individuals as they have higher levels of inflammation, oxidative stress, and vascular dysfunction.
This is difficult to interpret; the team say, as there is evidence that flavonoids influence body composition.
Here the gut microbiome may be significant as studies have shown its role in flavonoid metabolism and therefore bioactivity and is dissimilar in obese individuals.
Source: Nature Communications
Published online: DOI: 10.1038/s41467-019-11622-x
“Flavonoid intake is associated with lower mortality in the Danish Diet Cancer and Health Cohort.”
Authors: Nicola Bondonno et al.