Vegetarianism, female gender and increasing age, but not CNDP1 genotype, are associated with reduced muscle carnosine levels in humans

Abstract

Carnosine is found in high concentrations in skeletal muscles, where it is involved in several physiological functions. The muscle carnosine content measured within a population can vary by a factor 4. The aim of this study was to further characterize suggested determinants of the muscle carnosine content (diet, gender and age) and to identify new determinants (plasma carnosinase activity and testosterone). We investigated a group of 149 healthy subjects, which consisted of 94 men (12 vegetarians) and 55 women. Muscle carnosine was quantified in M. soleus, gastrocnemius and tibialis anterior using magnetic resonance proton spectroscopy and blood samples were collected to determine CNDP1 genotype, plasma carnosinase activity and testosterone concentrations. Compared to women, men have 36, 28 and 82% higher carnosine concentrations in M. soleus, gastrocnemius and tibialis anterior muscle, respectively, whereas circulating testosterone concentrations were unrelated to muscle carnosine levels in healthy men. The carnosine content of the M. soleus is negatively related to the subjects' age. Vegetarians have a lower carnosine content of 26% in gastrocnemius compared to omnivores. In contrast, there is no difference in muscle carnosine content between omnivores with a high or low ingestion of β-alanine. Muscle carnosine levels are not related to the polymorphism of the CNDP1 gene or to the enzymatic activity of the plasma carnosinase. In conclusion, neither CNDP1 genotype nor the normal variation in circulating testosterone levels affects the muscular carnosine content, whereas vegetarianism, female gender and increasing age are the factors associated with reduced muscle carnosine stores.

Effects of Acute Beta-Alanine Supplementation on Anaerobic Performance in Trained Female Cyclists

“…When comparing intramuscular carnosine between males and females, a 3.5 : 1.0 ratio exists respectively between genders (8). Females also require lower levels of BA supplementation to obtain similar relative increases in carnosine compared to males (9).…”

β–alanine: performance effects, usage and side effects

“…Similarly, a decline of 63% of M-HCD concentration in human patients with neuromuscular disease aged between 10 and 70 years has been reported [56]. Everaert et al, [58] found a negative correlation between age and carnosine concentration in the soleus muscle in humans. This represents a decline of soleus carnosine concentration of 1.2% each year, however the majority of participants were younger than 30 years of age.…”

“…However, there was no correlation between free testosterone and M-Carn content found by Everaert et al [58] in young men. Also, the age-related changes in testosterone [67,68] are not the same as the age-related changes in M-Carn.…”

“…The differences in M-Carn content found by Everaert et al [58] were from whole muscle and did not account for muscle fibre composition. The gender differences in M-Carn during puberty may be explained by the larger cross sectional area of type II fibres present in males versus females [69,70].…”

“…There were no obvious sex differences in the M-Carn content of the gluteus medius of 1 year old male and female thoroughbred horses [64]. In humans, males have approximately 21% greater M-Carn content than women in the quadriceps femoris muscle [65], 28% in the gastrocnemius, 36% in the soleus and 82% in the tibialis anterior [58]. The authors suggest that the differences in M-Carn content may be a contributing factor to the gender differences in performance during high-intensity exercise.…”