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.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-04132009-145623 |
| Date | 15 April 2009 |
| Creators | MacCormick, Vanessa Marie |
| Contributors | Whiting, Susan J., Rodgers, Carol D., Chilibeck, Philip D., Zello, Gordon A. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-04132009-145623/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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