A methyl-group acceptor such as guanidinoacetic acid (GAA) could induce hyperhomocysteinemia with the effects of GAA expected to be dose-dependent. Due to the fact that hyperhomocysteinemia is thought to be an independent risk factor for cardiovascular and neurodegenerative diseases, different dietary agents were used in the past for the treatment of elevated total plasma homocysteine (T-HCy), e. g. betaine, choline (betaine precursor) or folic acid. In the context of GAA loading the question arises whether intake of betaine, choline (betaine precursor) or folic acid during GAA loading could affect plasma T-HCy in healthy humans. Forty healthy physically active men and women aged 20 to 30 years will take part in this GAA-controlled, double-blind and parallel-group intervention study. Subjects will be allocated to four randomly assigned trials, with treatment lasting for 8 weeks and washout period of 28 days. The 4 test treatment-groups will include TEST1 (GAA only), TEST2 (GAA, choline, B6, B12 and folic acid), TEST3 (GAA, betaine, B6, B12 and folic acid) and TEST4 (GAA, B6, B12 and folic acid). Plasma T-HCy will be the primary outcome measure assessed every second week throughout the study. Plasma B-vitamins and blood and urine metabolites (GAA, creatine, methionine, arginine) will be secondary outcome measures along with adverse-effects indicators assessed every second week throughout the study. Selected body composition indicators will be obtained at 0, 2, 8 and 12 weeks throughout the study to monitor the effects of experimental treatments on body hydration and protein synthesis. This research will test the hypothesis that a combination of GAA with homocysteine lowering nutrients attenuates the elevation of T-hcy, and will further display the size-effect of each additive used.
Inclusion Criteria:
Exclusion Criteria:
- total plasma homocysteine above 15.5 µmol/L