Association between serum 5-methyltetrahydrofolate and homocysteine in Chinese hypertensive participants with different MTHFR C677T polymorphisms: a cross-sectional study

BACKGROUND AND AIMS: Clarifying the association between 5-methyltetrahydrofolate and homocysteine and the effect pattern of methylene tetrahydrofolate reductase (MTHFR C677T) may contribute to the management of homocysteine and may serve as a significant reference for a randomized controlled trial of 5-methyltetrahydrofolate intervention. This study aimed to reveal the association between these two biochemical indices. METHODS: Study population was drawn from the baseline data of the China Stroke Primary Prevention Trial (CSPPT), including 2328 hypertensive participants. 5-methyltetrahydrofolate and homocysteine were determined by stable-isotope dilution liquid chromatography-tandem mass spectrometry and automatic clinical analyzers, respectively. MTHFR C677T polymorphisms were detected using TaqMan assay. Multiple linear regression was performed to evaluate the association between serum 5-methyltetrahydrofolate and homocysteine. RESULTS: There was a significant inverse association between 5-methyltetrahydrofolate and homocysteine when 5-methyltetrahydrofolate was ≤ 10 ng/mL, and this association was modified by MTHFR C677T (per 1-ng/mL increment; All: β = − 0.50, P < 0.001; CC: β = − 0.14, P = 0.087; CT: β = − 0.20, P = 0.011; TT: β = − 1.19, P < 0.001). Moreover, the decline in trend in genotype TT participants was stronger than in genotype CC participants (P for difference < 0.001) and genotype CT participants (P for difference < 0.001), while there was no significant difference between genotype CC and genotype CT participants (P for difference = 0.757). CONCLUSIONS: Our data showed a non-linear association between serum homocysteine and 5-methyltetrahydrofolate among Chinese hypertensive adults, however, it could be inversely linearly fitted when serum 5-methyltetrahydrofolate was ≤ 10 ng/mL, and this association was modified by MTHFR C677T. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12937-022-00786-w.