Supplementation with Methyl Donors during Guanidinoacetic Acid Loading in Humans

Abstract

The main aim of this study was to investigate whether dietary intake of methyldonors (e.g., betaine, choline and/or B vitamins) during guanidinoacetic acid (GAA)loading affected metabolic and clinical markers, and increased the incidence of sideeffectsafter 8 weeks of administration. Forty (n = 40) healthy men and women aged 18 to30 years were recruited for a GAA-controlled, double-blind and parallel-groupintervention study. Subjects were allocated to four randomly assigned trials: group A wassupplemented with pure GAA, group B with a formulation containing GAA, choline, andB vitamins, group C with GAA, betaine, and B vitamins, and group D with GAA and Bvitamins. Addition of methyl donors to GAA largely precluded the elevation of plasmatotal homocysteine caused by the GAA administration alone (P < 0.05). The intake of Bvitamins in groups B, C and D significantly increased levels of plasma folates, vitaminB12 and holo-transcobalamine (P < 0.05). Reported side-effects during the interventionwere transient and clinically irrelevant, and no major disturbances of clinical enzymesand other biochemical indicators of health status have been observed. It seems thataddition of methyl donors in combination with dietary GAA supplementation effectivelycompensated for methylation requirements, such that the administration can beconsidered as a relatively safe nutritional intervention.