High flavonoid intake benefits cognitive function in study of American men, women

Increased flavonoid consumption reduced the risk of subjective cognitive decline among men and women in the United States, according to findings published in Neurology.

“Although some small, short-term intervention trials have provided some evidence to support the beneficial role of flavonoids on cognitive decline, epidemiological studies have remained inconclusive. Further, whether different flavonoid subclasses and specific foods contributing to flavonoid intake possess distinct relationships with cognitive function is unclear,” Tian-Shin Yeh, MD, PhD, a research fellow in epidemiology at Harvard T.H. Chan School of Public Health, and colleagues wrote. “Therefore, we investigated the relationships between intake of flavonoids and subsequent subjective cognitive decline (SCD) using comprehensive repeated dietary assessments from over 20 years of follow-up in two large prospective cohorts of men and women.”

Yeh and colleagues analyzed data from 27,842 men aged 40 to 75 years from the Health Professionals Follow-up Study (HPFS; 1986-2002) and 49,493 women aged 30 to 55 years from the Nurses’ Health Study (NHS; 1984-2006).

Researchers used Poisson regression to assess the associations between dietary flavonoids, including flavonols, flavones, flavanones, flavan-3-ols, anthocyanins, polymeric flavonoids and proanthocyanidins) and subsequent SCD. The NHS cohort took seven repeated food frequency questionnaires (SFFQs) to determine long-term average dietary intake, and their SCD was evaluated in 2012 and 2014. The HPFS cohort took five repeated SFFQs and their SCD was assessed in 2008 and 2012.

The pooled results showed that, after adjusting for age, total energy intake, major non-dietary factors and specific dietary factors, a higher consumption of flavonoids correlated with lower odds of SCD. When comparing the highest vs. lowest quintiles of flavonoid consumption, the pooled multi-variable-adjusted ORs of 3-unit increments in SCD were 0.81 (95% CI, 0.76-0.89).

Additionally, the strongest correlations in the pooled results were seen for flavones (OR = 0.62; 95% CI, 0.57-0.68), flavanones (OR = 0.64; 95% CI, 0.58-0.68) and anthocyanins (OR = 0.76; 95% CI, 0.72-0.84).

Limitations of this study include the lack of baseline cognitive assessments, as well as the presence of potential recall bias in participants and generalizability, as the participants were mainly white health care professionals.

“Our findings support a benefit of higher flavonoid intakes for maintaining cognitive function in US men and women,” Yeh and colleagues wrote. “These findings may suggest future interventional studies in search of possible therapeutic or preventive strategies for cognitive decline, including the possible effects of specific flavonoids on cognitive function and the effective dosage. In the meantime, consumption of flavonoid-rich foods, such as berries, and citrus fruits and juices, may be beneficial to maintain cognitive function.”