The association between intake of main flavonoid classes and menopausal age: a population-based and cross-sectional study

Menopausal age represents the endpoint of the entire reproductive cycle of women, and it is a biological marker that indicates the overall health and ageing status of women. Flavonoids are the most common polyphenolic compounds in the daily diet, and their intake is related to reduced risks of certain diseases. Our study aimed to analyse the relationships between the intake of flavonoids and menopausal age. We selected 29 940 participants from National Health and Nutrition Examination Survey database from 2007-2008, 2009-2010 to 2017-2018. A total of 680 participants were included in our analysis after screening. Multiple logistic regression was used to explore the association between dietary flavonoid subclasses intake and menopausal delay (≥ 55 years old). Restricted cubic splines plots were generated to reveal the nonlinear relationships between the subclasses of flavonoids intake and menopausal age. According to the adjusted multiple factor logistic regression analysis, the top quartile intake (compared with bottom intake) of anthocyanidins was positively associated with delayed menopause (OR = 4·123; 95 % CI: 1·130, 15·041; <i>P</i>_trend = 0·036), whereas the moderate intake of flavonols was negatively associated with delayed menopause (Q2 <i>v</i>. Q1, OR = 0·081 (95 % CI: 0·025, 0·261), <i>P</i>_trend = 0·001; Q3 <i>v</i>. Q1, OR = 0·271 (95 % CI: 0·093, 0·791), <i>P</i>_trend = 0·023). The restricted cubic splines revealed that non-linear association was observed between the intake of isoflavones, flavan-3-ols, flavonols and later menopause (<i>P</i> value for non-linearity < 0·05). Our findings suggest that specific dietary flavonoids intake may have potential roles in regulating menopausal timing.