Optimizing human in vivo dosing and delivery of β-alanine supplements for muscle carnosine synthesis

Abstract

Interest into the effects of carnosine on cellular metabolism is rapidly expanding. The first study to demonstrate in humans that chronic β-alanine (BA) supplementation (~3-6 g BA/day for ~4 weeks) can result in significantly augmented muscle carnosine concentrations (>50%) was only recently published. BA supplementation is potentially poised for application beyond the niche exercise and performance-enhancement field and into other more clinical populations. When examining all BA supplementation studies that directly measure muscle carnosine (n=8), there is a significant linear correlation between total grams of BA consumed (of daily intake ranges of 1.6-6.4 g BA/day) versus both the relative and absolute increases in muscle carnosine. Supporting this, a recent dose-response study demonstrated a large linear dependency (R2=0.921) based on the total grams of BA consumed over 8 weeks. The pre-supplementation baseline carnosine or individual subjects' body weight (from 65 to 90 kg) does not appear to impact on subsequent carnosine synthesis from BA consumption. Once muscle carnosine is augmented, the washout is very slow (~2%/week). Recently, a slow-release BA tablet supplement has been developed showing a smaller peak plasma BA concentration and delayed time to peak, with no difference in the area under the curve compared to pure BA in solution. Further, this slow-release profile resulted in a reduced urinary BA loss and improved retention, while at the same time, eliciting minimal paraesthesia symptoms. However, our complete understanding of optimizing in vivo delivery and dosing of BA is still in its infancy. Thus, this review will clarify our current knowledge of BA supplementation to augment muscle carnosine as well as highlight future research questions on the regulatory points of control for muscle carnosine synthesis.

New strategies in sport nutrition to increase exercise performance

“…The optimal loading protocol is unknown but intakes of 3-6 g/d for [4][5][6][7][8][9][10][11][12] weeks increase this intracellular buffer by 50-85% [136]. To date, no threshold for carnosine concentrations has been found, but a daily intake of ~ 1.2 g appears to maintain muscle carnosine elevations and a return to baseline may require 6-20 weeks of supplement withdrawal [137].…”

“…whale). Supplementation with doses > 800 mg of purified b-alanine is associated with symptoms of paresthesia (skin tingling), but this sometimes unpleasant side-effect can be managed with slow-release tablets or spreading doses over the day [136]. Theoretically this chronically applied supplement can enhance the performance of a single competition, but also support the training process.…”

β–alanine: performance effects, usage and side effects

“…This is highlighted in Figure 2.2, which shows the relationship between β-alanine consumption and the percentage increase in M-Carn. From [98].…”

“…Stellingwerf et al [101] recently showed that despite an equal absolute change in M-Carn levels in different muscles, the relative change varies because of different baseline levels. Therefore there will always be differences in baseline M-Carn levels when comparing biopsy and 1 H-MRS data [98].…”

“…Increases in muscle creatine have been negatively correlated to high baseline creatine values [102]. Stellingwerf et al [98] hypothesised that individuals with low baseline carnosine levels such as vegetarians, females or the elderly [58], might respond to a greater extent to β-alanine supplementation than those having higher resting concentrations. However, contrary to this hypothesis Baguet et al [100] found a positive correlation between high baseline levels and the increase in M-Carn in eight elite rowers.…”