Elevation of creatine in red blood cells in vegetarians and nonvegetarians after creatine supplementation.

The purpose of this study was to examine the effect of a 5-day creatine (CR) supplementation period on red blood cell (RBC) CR uptake in vegetarian and nonvegetarian young women. Blood samples were collected from lacto-ovo vegetarians (VG, n = 6, age 21.8 +/- 1.9 yrs) and nonvegetarians (NV, n = 6, age 21.7 +/- 1.9 yrs) before and after a 5-day CR loading period (0. 3g CR/kg lean body mass/day), and from a control group of nonvegetarians (NV, n = 5, age 22.0 +/- 0.7 yrs) who did not supplement with creatine. RBC and plasma samples were analyzed for the presence of creatine. Significant increases (p < .05) in RBC and plasma CR levels were found for vegetarians and nonvegetarians following supplementation. The initial RBC CR content was significantly lower (p < .05) in the vegetarian group. There was no significant difference between vegetarians and nonvegetarians in final RBC CR content, suggesting that a ceiling had been reached. As the uptake into both muscle and RBC is moderated by creatine transporter proteins, analysis of the uptake of CR into RBC may reflect the uptake of CR into muscle, offering an alternative to biopsies.