FOLSOM, Calif. – May 15, 2023 – A new research study published in BMC Medicine found eating more flavonoid-rich foods, specifically tea, blueberries, red wine and peppers, was associated with up to an 11% reduction in all-cause mortality. Flavonoids are the most abundant and most researched class of polyphenols, a group of phytochemicals, which demonstrate important anti-inflammatory and cholesterol-lowering effects. 1 This research comes on the heels of new food-based intake recommendations for dietary flavan-3-ols – a subgroup of flavonoids – and cardiometabolic health, and adds to the growing body of evidence demonstrating the importance of bioactive compounds for optimal health. 2 This is the first study of its kind to examine the associations between changes in intake of flavonoid-rich foods and risk of all-cause and cause-specific mortality. The researchers specifically evaluated associations between 8-year changes in intakes of (1) individual flavonoid-rich foods and (2) a novel composite measure of flavonoid-rich foods and beverages, a term referred to as the flavodiet.
This prospective cohort study looked at data from 55,768 health professional females from the Nurses’ Health Study (NHS) and 29,800 health professional males, primarily Caucasian, from the Health Professionals Follow-up Study (HPFS), without chronic disease. Participants completed validated semi-quantitative food frequency questionnaires (FFQs) in 1986 and were invited to repeat these questionnaires every 4 years, until 2010, and were followed for health outcomes until 2018. Participants were asked how often, on average, they consumed a standard portion of each flavonoid-rich food and beverage in the past year with frequency response categories ranging from never or less than once a month, to six or more times per day [specifically, blueberry (½ cup), apple (1 fruit), orange (1 fruit) plus orange juice (1 small glass), grapefruit (½ fruit) plus grapefruit juice (1 small glass), strawberry (½ cup), tea (8 oz. cup), red wine (5 oz. glass), onion (1 slice raw or ½ cup cooked), peppers (2 rings or ¼ small), and grapes (½ cup) plus raisins (1 oz. or 1 small pack)]. 3 4
Additionally, intakes of flavonoid-rich foods/ beverages that contributed >1% to total flavonoid intakes in both the NHS and the HPFS at all waves of follow-up were combined to create a ‘flavodiet’ score [i.e., tea, apples, oranges, grapefruits, blueberries, strawberries and red wine (servings/day)]. Death from any cause was the primary outcome for these analyses.
The results of this study illustrate that eating more flavonoid-rich foods, even in mid-life, can have a potential beneficial impact on risk of early mortality. For the flavodiet score, researchers showed that an achievable three servings/day increase in intake of flavonoid-rich foods (e.g., one cup of tea, ½ cup of blueberries and one glass of red wine) was associated with an 8% and 13% lower risk of all-cause and neurological death, respectively. More specifically, a one serving every other day (3.5 servings/week) increase in the intake of blueberries was associated with a 5% lower risk of all-cause mortality. This appeared to be driven by a trend for a high risk of mortality in participants who lowered their intakes of blueberries.
“The result of our research illustrates that modifying eating behaviors in mid to later life can influence health outcomes and a dietary pattern higher in flavonoid-rich foods and beverages, including blueberries, peppers, tea, and red wine, may offer distinct benefits,” said Aedin Cassidy, PhD, Chair of Nutrition & Preventive Medicine and Director of Interdisciplinary Research Institute for Global Food Security, Queen’s University, Belfast, Ireland and the study’s lead investigator. “Eating more plant-based foods and beverages rich in flavonoids, even in mid-life, may have a real impact on risk of early mortality, as illustrated by our novel flavodiet score.”
This study was supported by grants from the National Institutes of Health and funding from the U.S. Highbush Blueberry Council. Further research is needed to replicate these findings in other populations. Furthermore, these two cohorts are not representative of the general population as they include only nurses or health professionals and participants were mostly Caucasian. Additionally, because of the potential for reverse causation to influence these findings, further studies of these relationships are needed.
“While further studies are warranted, the results of this study suggest that the benefits of flavonoids are best obtained from the frequent consumption of whole foods, including blueberries,” said Eric Rimm, ScD, Professor of Epidemiology and Nutrition and Director of the Program in Cardiovascular Epidemiology at the Harvard T.H. Chan School of Public Health and a study co-investigator. “This study adds to the growing body of evidence demonstrating an association between flavonoids – including anthocyanins and flavon-3-ols – and improved health outcomes.”
The USHBC had no role in study design, data collection, data analysis, data interpretation, or writing of the study. For more information on blueberry nutrition research visit https://healthprofessionals.blueberry.org/research/
1 Panche AN, Diwan AD, Chandra SR. Flavonoids: an overview. J Nutr Sci. 2016 Dec 29;5:e47. doi: 10.1017/jns.2016.41. PMID: 28620474; PMCID: PMC5465813.
2 Crowe-White, K. M., Evans, L. W., Kuhnle, G. G., Milenkovic, D., Stote, K., Wallace, T., … & Senkus, K. E. Flavan-3-ols and Cardiometabolic Health: First Ever Dietary Bioactive Guideline. Advances in Nutrition, 2022;13(6), 2070-2083.
3 Bertoia ML, Rimm EB, Mukamal KJ, Hu FB, Willett WC, Cassidy A. Dietary flavonoid intake and weight maintenance: three prospective cohorts of 124 086 US men and women followed for up to 24 years. BMJ. 2016;352:i17.
4 Cassidy A, Rimm EB, O’Reilly ÉJ, Logroscino G, Kay C, Chiuve SE, et al. Dietary flavonoids and risk of stroke in women. Stroke. 2012;43(4):946–51.