Association was found between tea and neural tube defects. However, few studies investigated the relationship between tea consumption and blood folate levels. We aimed to investigate the association between tea consumption and plasma folate concentrations among women aged 18–30 years in different ethnicities of China.

Data were obtained from a national cross-sectional study conducted from 2005 to 2006 of women aged 18–30 years in China. Socio-demographic characteristics and lifestyle were obtained from a questionnaire. Dietary folate intake was determined by 24-h dietary recall. Plasma folate concentrations were measured by a microbiological assay. Multiple linear regression model was used to calculate partial regression coefficients after adjusting for confounding factors.

Nine provinces or autonomous regions in China.

A total of 2932 women aged 18–30 years in China.

After stratifying by ethnicity and tea type, tea consumption was significantly positively associated with plasma folate levels in Han women who drank unfermented tea weekly (β = 0·067, and P = 0·037) or daily (β = 0·119, and P = 0·031) and in Uighur women who drank fermented tea weekly (β = 0·325, and P = 0·028). For women who drank unfermented tea in Han ethnicity, weekly and daily tea drinkers had 6·77 % (95 % CI: 6·36 %, 7·21 %) and 7·13 % (95 % CI: 6·40 %, 7·96 %) increase in plasma folate concentration compared with no tea drinkers.

There is a suggestion of possible positive association between unfermented tea drinking in Han ethnicity and plasma folate concentrations, for Chinese women aged 18–30 years. The relationship between tea drinking in other ethnic groups and plasma folate still needs to be further explored.