Changes in serum homocysteine in response to oral creatine supplementation in vegetarians
MacCormick, Vanessa Marie
Homocysteine (Hcy) is metabolized through a series of remethylation and transsulphuration processes that require the co-factors vitamins B6, folate (the nutrient derived from food, and folic acid is supplemental), and B12. Homocysteine metabolism results in the production of creatine (Cr). By way of negative feedback creatine supplements could potentially decrease Hcy production. Low dietary intake of vitamins and creatine, often a consequence of a vegetarian diet may also increase serum Hcy concentrations. It was therefore the purpose of this study to examine the effect of a five day creatine loading period (0.25 g Cr/kg lean body mass (LBM)/day) in female vegetarians (VG) (n=9, age 25 ± 3.6) and non-vegetarians (NV) (n=11, age 24 ± 5.9) on serum levels of Hcy, vitamins B6 and B12, whole blood folate, and on a number of fitness measures known to be positively affected by creatine supplementation: peak torque and average power during leg extensions; one repetition maximum (1RM) bench and leg press; peak power during repeated Wingate anaerobic tests. Aside from a difference in change scores for leg press, there were no differences between dietary groups for the fitness measures, and therefore the participants were pooled for comparisons between time points. Urinary creatine was significantly greater following the five day loading period (81 ± 113 vs. 647 ± 421 µmol). In contrast, urinary creatinine did not change. A significant increase in plasma vitamin B6 (pyridoxal 5’-phosphate) was found (72 ± 24 vs. 94 ± 24 nmol/L) (p < 0.05), although there were no between group differences. Serum Hcy, vitamin B12, and whole blood folate levels did not change significantly over time in either group. Participants showed significant increases post-loading in bench press (45 ± 13 vs. 48 ± 12 kg.) and leg press (116 ± 35 vs. 125 ± 40 kg) (p < 0.05). Changes scores for leg press were greater for the vegetarian participants when compared with non-vegetarians (16 ± 16 vs. 3 ± 9 kg). Significant improvements post-loading were also noted for peak torque (85.0 ± 15.0 vs. 91.8 ± 12.9 Nm) and average power (99.5 ± 14.4 vs. 107.1 ± 14.8 W) (p < 0.05). Peak power during repeated Wingate anaerobic tests also significantly improved in response to the intervention (449.2 ± 92.6 vs. 472.4 ± 103.5 W) (p < 0.05). This response did not differ however between the two diet groups. These results suggest that a five day creatine loading protocol similarly affects fitness performance measures in both vegetarians and non-vegetarians. There was no significant effect of the supplementation protocol on serum Hcy concentration, suggesting that the supplemented creatine did not decrease the reformation of Hcy, as originally hypothesized.
DegreeMaster of Science (M.Sc.)
DepartmentCollege of Kinesiology
ProgramCollege of Kinesiology
SupervisorRodgers, Carol D.
CommitteeWhiting, Susan J.; Chilibeck, Philip D.; Zello, Gordon A.