Food-sourced guanidinoacetic acid and methylation cycle biomarkers in individuals aged one year and older: a population-based cross-sectional study

Purpose Several preliminary studies suggest dietary guanidinoacetic acid (GAA) might impact methyl group availability and/or methylation biomarkers, fueling ongoing debates. This study aimed to explore the relationship between dietary GAA intake and plasma indicators of the methylation cycle in individuals aged one year and older, using data from the 2001–2002 National Health and Nutrition Examination Survey (NHANES). Methods Dietary information was obtained from individuals who completed a 24-hour Dietary Recall, with total daily intake of GAA calculated by aggregating all relevant food items. Relevant variables related to the methylation cycle, such as red blood cell (RBC) folate and serum folate, vitamin B12, total homocysteine (tHCy), and methylmalonic acid (MMA), were identified from the NHANES 2001–2002 laboratory assessments. Results A total of 9,115 individuals (51.3% females) were included in the final analysis. Linear regression unveiled a significant association between higher GAA intake and diminished RBC folate ( p