Twenty-four Weeks Of Beta-alanine Supplementation (using a Sustained Release Formulation) Increases Muscle Carnosine Content Despite Downregulation Of Beta-alanine Transporter Expression Bryan Saunders1, Vitor de Salles Painelli1, Luana Farias de Oliveira1, Vinicius da Eira Silva1, Rafael Pires da Silva1, Luiz Riani1, 1 1 2 1 3 3 1 Mariana Franchi , Lívia de Souza Gonçalves , Roger Charles Harris , Hamilton Roschel , Guilherme Giannini Artioli , Craig Sale , Bruno Gualano 1: University of São Paulo, Brazil. 2: Junipa Ltd, UK. 3: Nottingham Trent University, UK. ABSTRACT Skeletal muscle carnosine content can be increased via chronic beta-alanine ingestion, but the maximum increase achievable with supplementation is unknown. Additionally, the effects of prolonged supplementation on carnosine-related gene expression in humans are not known. Since athletes are likely to supplement for extended periods of time, determination of the long-term effects of beta-alanine supplementation is warranted. PURPOSE: To investigate the effects of 24-weeks of beta-alanine supplementation on muscle carnosine content and expression of genes related to carnosine metabolism. METHODS: Twenty-four males were supplemented with 6.4 g·day-1 of sustained release beta-alanine (BA; N=15) or placebo (PL; N=9) for 24 weeks. Every 4 weeks participants provided a muscle biopsy from the m. vastus lateralis, which was subsequently analysed for muscle carnosine content and gene expression (CARNS, TauT, ABAT, CNDP2, PHT1, PEPT2, PAT1). RESULTS: Carnosine content was increased from baseline at every time point in BA (all P0.05). Maximal changes ranged from +17.1 to +41.3 mmol·kg-1dm, and absolute maximal content ranged from 31.8 to 63.9 mmol·kg-1dm. There was an effect of supplement (P=0.002) on TauT with lower expression in BA (-36%, -39%, -27%, -57%, -46% and -35% at Weeks 4, 8, 12, 16, 20 and 24); no further differences in gene expression were shown. CONCLUSION: Twentyfour weeks of beta-alanine supplementation increased muscle carnosine content in all individuals at all time points, although absolute maximal changes were variable. Downregulation of the beta-alanine transporter TauT suggests it plays an important role in muscle carnosine accumulation with beta-alanine supplementation. These data demonstrate that individuals who supplement with beta-alanine for prolonged periods can maintain elevated muscle content throughout supplementation, despite downregulation of beta-alanine transporter expression.
INTRODUCTION • Beta-alanine (BA) increases muscle carnosine (MCarn) content following 4-10 wk supplementation:
METHODS
RESULTS (continued)
Twenty-four recreationally active males (age 27 ± 4 y, height 1.75 ± 0.09 m, body mass 78.9 ± 11.7 kg) participated in the study.
Maximal MCarn increases ranged from +17.1 to +41.3 mmol·kg-1dm, and absolute maximal content ranged from 31.8 to 63.9 mmol·kg-1dm.
Participants were supplemented with 6.4 g·day-1 of sustained release BA (CarnoSynTM, NAI, USA) or placebo (PL; maltodextrin, NAI, USA) for 24 wk.
There was an effect of supplement (P=0.002) on TauT with lower expression in BA (-36%, -39%, -27%, -57%, -46% and -35% at Weeks 4, 8, 12, 16, 20 and 24; Figure 2); no further differences in gene expression were shown (all P>0.05).
Every 4 wk participants underwent a muscle biopsy of the m. vastus lateralis; samples were analysed for MCarn content via HPLC and gene expression (CARNS, TauT, ABAT, CNDP2, PHT1, PEPT2, PAT1) via RealTime PCR. Data were analysed using mixed model analysis using the SAS statistical package (SAS 9.2, SAS Institute Inc., USA)
RESULTS MCarn content was increased from baseline at every time point in BA (all P≤0.0001; Figure 1), but not PL (all P>0.05). Increases in MCarn content in BA: Week 4:
+11.37 ± 7.03 mmol·kg-1dm;
Week 8:
+13.88 ± 7.84 mmol·kg-1dm;
Week 12:
+16.95 ± 8.54 mmol·kg-1dm;
Week 16:
+17.63 ± 8.42 mmol·kg-1dm;
Week 20:
+21.20 ± 7.86 mmol·kg-1dm;
Week 24:
+20.15 ± 7.63 mmol·kg-1dm;
•Harris et al. (2006) – 4 wk (5.2 g·day-1):
↑MCarn 7.8 ± 0.4 mmol·kg-1dm
•Hill et al. (2007) – 4 wk (5.2 g·day-1):
Figure 2. Fold change of TauT across the 24 weeks in BA (black bars) and PL (white bars). *P=0.002 Main effect of BA. Data are mean±1SD.
↑MCarn 10.2 ± 3.2 mmol·kg-1dm
– 10 wk (5.9 g·day-1): ↑MCarn 14.8 ± 3.7 mmol·kg-1dm
DISCUSSION
The maximum increase achievable with BA supplementation is unknown
Twenty-four weeks of BA supplementation increased MCarn content in all individuals at all time points, although absolute maximal changes were variable.
• A number of genes and their resulting proteins regulate the processes affecting MCarn content:
Downregulation of the BA transporter TauT suggests it may play an important role in MCarn accumulation with BA supplementation.
– Carnosine synthesis (CARNS);
The data demonstrate that individuals who supplement with BA for prolonged periods can continue to elevate MCarn content throughout supplementation, despite downregulation of BA transporter expression.
– β-alanine transport (TauT, PAT1, ATB0,+); – Carnosine hydrolysis (CNDP1, CNDP2); – β-alanine transaminase (ABAT);
REFERENCES
– Carnosine/histidine transport (PEPT1, PEPT2, PHT1, PHT2).
Harris et al. (2006). Amino Acids. 30(3), 279-289. Hill et al. (2007). Amino Acids. 32(2), 225-33.
The effects of prolonged supplementation on carnosine-related gene expression in humans are unknown.
Purpose: To investigate the effects of 24 wk of BA supplementation on MCarn content and expression of genes related to carnosine metabolism.
Figure 1. Muscle carnosine content throughout supplementation in BA (black circles) and PL (white circles). aP≤0.0001 from Week 0. bP≤0.0001 from PL at same time point. Data are mean ± 1SD.
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Full study results are now available: Saunders et al. (2017). Medicine & Science in Sports & Exercise, 49(5): 896-906.
