L-carnosine is a dipeptide, that is, a molecule composed of two amino acids, β-alanine and L-histidine. In addition to being present in food, this is marketed as a supplement/supplement with potential uses for both sport and health.
In sports, L-carnosine is not actually considered as not very bioavailable, as opposed to the β-alanine precursor, which is widely studied and validated as a supplement to improve sports performance. In the medical field carnosine is currently being studied, with promising potential for health and for the treatment of many chronic diseases.
Carnosine in sports
Carnosine has great popularity in sports, not so much as a supplement, but due to the fact that a greater concentration of this molecule in the muscles allows obtaining an improvement of various types of performance-related to endurance (1), an in-depth topic in the article on beta-alanine.
Carnosine intended as a supplement is not used in sports as it has a low bioavailability, that is to say, that following ingestion it is largely degraded in its basic molecules β-alanine and L-histidine (by the enzyme carnosinase ), while only a small part accesses intact blood (1,2).
Carnosine, therefore, is unable to bring the known benefits for performance by increasing its stocks in the muscle: for this reason, beta-alanine, its precursor, is needed, which bypasses the problem of bioavailability.
Even β-alanine is actually not very bioavailable after ingestion (5), however, it is observed that after a chronic intake phase of several weeks (at least 4 to 10), the amino acid still manages to overcompensate the carnosine stocks in the muscles and act as an effective ergogenic.
Carnosine in therapy
As with many other amino acid supplements, carnosine (or an increase in its synthesis by integrating β-alanine) can also be used in the medical field and has been proposed for neurodegenerative diseases, diabetes, insulin resistance, nephropathies, heart disease, cancer, and other chronic diseases. (3,4). Carnosine is also proposed as a health supplement, in particular to improve the quality of life and longevity in the elderly or cognitive functions (3).
This would act thanks to its anti-inflammatory, antioxidant, anti-glycan, anti-ischemic, and typical chelating properties (4). The supplement is currently under study but appears to be very promising for all these series of benefits, although its β-alanine precursor is often preferred due to the greater bioavailability (3).
The problem of bioavailability
The big problem associated with carnosine as a supplement is a low bioavailability for most people. Only some subjects (about 1/3 according to some studies) can be defined as “responders”, for whom a significant increase in carnosine plasma levels is observed, thanks to lower activity of the carnosinase enzyme (ie the person responsible for degradation) (2 5).
But even for the few “responders”, the doubt remains that dipeptide could have a significant effect, given the increase in blood only for a short time (2). For this reason, an attempt has been made to circumvent the problem by developing conjugated formulas, resistant to the carnosinase enzyme, which manage to have an effect (2).
Other studies have observed that the combination with dipeptide anserine (in a 2: 1 ratio) increases its bioavailability (6) and recent research observes that the local application of a patented formula in gel form (LactiGo ™) is able to improve sports performance shortly after application (5).
As mentioned above, in most cases β-alanine is used to obtain the beneficial effects of carnosine, thanks to greater bioavailability. But in some researches carnosine is also used, with doses ranging from 0.5 to 4 g (4.5), or 60 mg/kg (4.5 g for a man of 75 kg, 2.7 g for a woman of 45 kg) ( 3.5). Given the low bioavailability for most people, it may be prudent to choose the highest dosages within the indicated range or directly 60 mg/kg.
If the aim is to obtain the benefits of physical activity, it is advisable to opt for beta-alanine, which probably also makes sense for therapeutic or health purposes. It is currently unclear why normal L-carnosine should be chosen directly over beta-alanine, and research updates are awaited to obtain an answer.
- Matthews JJ et al. The physiological roles of carnosine and β-alanine in exercising human skeletal muscle. Med Sci Sports Exerc. 2019 May 10.
- Salt C et al. Carnosine: from exercise performance to health. Amino Acids. 2013 Jun; 44 (6): 1477-91.
- Artioli GG et al. Carnosine in health and disease. Eur J Sport Sci. 2019 Feb; 19 (1): 30-39.
- Menon K et al. Effects of supplementation with carnosine and other histidine-containing dipeptides on chronic disease risk factors and outcomes: protocol for a systematic review of randomized controlled trials. BMJ Open. 2018 Mar 22; 8 (3): e020623.
- Sharpe TM, Macias CJ. Evaluation of the efficacy of Lactigo ™ topical gel as an ergogenic aid. J Exerc Physiol Online. 2016 Jul; 19 (3): 15-23.
- Peters V et al. Anserine inhibits carnosine degradation but in human serum carnosinase (CN1) is not correlated with histidine dipeptide concentration. Clin Chim Acta. 2011 Jan 30; 412 (3-4): 263-7.