Dietary intake of flavonoids found in tea helps lower risk of glioma

Increased dietary intakes of flavan-3-ol and polymeric flavonoids, particularly those found in tea, appears to reduce the risk of glioma in a prospective cohort of men and women, reveals a US study.

Participants in the female Nurses’ Health Study (1984–2014; n=81,688) and Nurses’ Health Study II (1991–2017; n=95,228) and the male Health Professionals Follow-Up Study (1986–2014; n=49,885) were followed in this study.

The authors assessed the associations between average long-term (up to 30 years) or recent (up to 12 years) dietary flavonoid intake (total flavonoids and each of six subclasses) and risks of incident glioma using multivariable-adjusted Cox proportional hazards regression models.

Flavonoid intake was derived from validated quadrennial food frequency questionnaires. Participants self-reported incident glioma, which was then confirmed by a medical record review or determined by a medical record review after death.

A total of 536 incident glioma cases were recorded across 5,936,386 person-years of follow-up.

In pooled analyses comparing the highest to lowest quintiles of consumption, long-term total flavonoid (hazard ratio [HR], 0.79, 95 percent confidence interval [CI], 0.58–1.05; p=0.04), flavan-3-ol (HR, 0.76, 95 percent CI, 0.57–1.01; p=0.04), and polymeric flavonoid (polymer; HR, 0.82, 95 percent CI, 0.61–1.09; p=0.05) intakes correlated with reduced glioma risks.

Of note, associations were weaker with recent intake. No association was observed with other flavonoid subclasses. After further adjustment for tea consumption, no associations were also found between flavan-3-ol or polymer consumption and glioma.

“Flavonoids are a diverse group of plant constituents with demonstrated neuroprotective and antitumour effects” the authors said.