Are there any concerns or considerations?
- Acute doses of instant release ß-alanine exceeding 800-1600 mg result in paraesthesia which is an uncomfortable tingling sensation on the skin that can last up to an hour. Although the exact cause of paraesthesia is unknown, it is thought to be due to ß-alanine activated strychninesensitive glycine receptor sites in the brain and central nervous system and the mas-related gene family of G protein coupled receptors18, which are triggered by interactions with ß-alanine.19 Sustained release formulations directly reduce the symptoms of paraesthesia.
- Human skeletal muscle has an extremely large capacity for carnosine loading and commonly used supplementation protocols (e.g., 4 weeks at 6.4 g·day−1) may not come close to saturating muscle carnosine. Further research is required to better understand the efficacy of longer supplementation protocols in order to maximise muscle carnosine.
- The carnosine loading efficiency following chronic orally ingested ß–alanine is very low (~3%)12 so further strategies could be developed to increase carnosine loading efficiency.
- Although ß-alanine is considered the rate-limiting precursor for carnosine synthesis, one recent study7 demonstrated that L-histidine levels were significantly decreased in blood plasma (-30.6%) and muscle (-31.6%) in subjects who supplemented with ß-alanine alone (6.0 g·d-1 for 23 d), while the decrease in L-histidine was prevented when ß-alanine and L-histidine (3.5 g·d-1) were supplemented simultaneously. Furthermore, despite not being statistically significant, Varanoske et al.13 observed an ~18.0% decrease in muscle L-histidine following 28 d of ß-alanine supplementation (6.0 g·d-1). However, more research is required to determine the significance of the decline in L-histidine observed in some studies and whether the co-supplementation of L-histidine and ß-alanine is advantageous compared to ß-alanine supplementation alone.
- Given the chronic nature of the ß-alanine supplementation protocol required for carnosine loading, ß-alanine products may be expensive and require a substantial financial commitment. Therefore, the athlete should be assured that they are using a sound supplementation protocol and applying it to a situation in which there is evidence or a strong hypothesis of performance enhancement.
- Given that ß-alanine supplementation may enhance training capacity during sprint-interval training, athletes should consider the possibility of an increased risk of injury, illness, or overreaching/fatigue.