Changing to a vegetarian diet reduces the body creatine pool in omnivorous women, but appears not to affect carnitine and carnosine homeostasis: a randomised trial

Abstract

Balanced vegetarian diets are popular, although they are nearly absent in creatine and carnosine and contain considerably less carnitine than non-vegetarian diets. Few longitudinal intervention studies investigating the effect of a vegetarian diet on the availability of these compounds currently exist. We aimed to investigate the effect of transiently switching omnivores onto a vegetarian diet for 6 months on muscle and plasma creatine, carnitine and carnosine homeostasis. In a 6-month intervention, forty omnivorous women were ascribed to three groups: continued omnivorous diet (control, n 10), vegetarian diet without supplementation (Veg+Pla, n 15) and vegetarian diet combined with daily β-alanine (0·8-0·4 g/d) and creatine supplementation (1 g creatine monohydrate/d) (Veg+Suppl, n 15). Before (0 months; 0M), after 3 months (3M) and 6 months (6M), a fasted venous blood sample and 24-h urine was collected, and muscle carnosine content was determined by proton magnetic resonance spectroscopy (1H-MRS). Muscle biopsies were obtained at 0M and 3M. Plasma creatine and muscle total creatine content declined from 0M to 3M in Veg+Pla (P=0·013 and P=0·009, respectively), whereas plasma creatine increased from 0M in Veg+Suppl (P=0·004). None of the carnitine-related compounds in plasma or muscle showed a significant time×group interaction effect. 1H-MRS-determined muscle carnosine content was unchanged over 6M in control and Veg+Pla, but increased in Veg+Suppl in soleus (P<0·001) and gastrocnemius (P=0·001) muscle. To conclude, the body creatine pool declined over a 3-month vegetarian diet in omnivorous women, which was ameliorated when accompanied by low-dose dietary creatine supplementation. Carnitine and carnosine homeostasis was unaffected by a 3- or 6-month vegetarian diet, respectively.

Benefits of Creatine Supplementation for Vegetarians Compared to Omnivorous Athletes: A Systematic Review

“…The minimum level of creatine supplementation required in vegetarians to prevent decreased creatine stores is probably about 1 g/day (the amount found in 200 g of steak) [47]. Blancquaert et al [34] randomized 40 female omnivores, with 10 continuing their normal diet, 15 going on a lacto-ovo vegetarian diet and supplementing with 1 g creatine/day, and 15 going on a lacto-ovo vegetarian diet and supplementing with placebo for six months. Vastus lateralis biopsies were collected at baseline and three months, and plasma at baseline, three months, and six months.…”

“…Creatine or phosphocreatine concentrations are most easily measured in the blood, but they have also been measured in muscle by obtaining biopsy samples or using 31 P-magnetic resonance spectroscopy ( 31 P-MRS) and in brain by 31 P-MRS or 1 H-MRS. Creatine concentrations are lower by about 50% in plasma [34,35], by 35-39% in serum [16], and by 27-50% in red blood cells [16,36] in vegetarians compared to omnivores.…”

“…Muscle biopsies from the vastus lateralis indicate that total creatine (i.e., creatine + phosphocreatine), phosphocreatine, and creatine concentrations are lower by 10-15%, 7-10%, and 7-26%, respectively, in vegetarians compared to omnivores [17,18,34,37]. In the lateral gastrocnemius, phosphocreatine levels, as assessed by 31 P-MRS, are similar in vegetarians and omnivores (i.e., a reduction in vegetarians by~5% that was not statistically significant) [33]; therefore, differences between vegetarians and omnivores seem to be muscle-specific.…”

Beyond sports: Efficacy and safety of creatine supplementation in pathological or paraphysiological conditions of brain and muscle

“…Despite this metabolic stress, however, they have a lower muscle concentration of creatine than omnivorous subjects. It seems, therefore, highly recommendable that they supplement their diet with creatine, 1 g/d being probably sufficient …”

“…It seems, therefore, highly recommendable that they supplement their diet with creatine, 1 g/d being probably sufficient. 57 This recommendation is particularly cogent when subjects following a vegetarian or vegan diet are athletes or heavy-work laborers, or when they undergo intense mental fatigue.…”