Carnosine is a dipeptide, a combination of two amino acids bonded together—histidine and beta-alanine. Since the body is loaded with histidine, the limiting factor in the production of carnosine is beta-alanine.
Why would you want to increase carnosine in your body? Carnosine was initially discovered in meat, which is the best natural source (as it is for creatine). In the 1930s scientists found that carnosine is a potent intramuscular buffer, meaning that stored in muscle it’s capable of “soaking up” excess hydrogen ions, the acid produced during high-intensity exercise. That pronounced burn you feel at the end of a hard set is caused by the build-up of lactic acid, produced as a waste product of anaerobic metabolism.
In fact, the lactate portion of lactic acid is not a waste product at all but can be reconverted into glucose in the liver, becoming a readily available energy source. The problem is the “acid” portion of lactic acid, since once the acid—or, more specifically, the hydrogen ions—increases in muscle, it begins to interfere with the production of enzymes required for energy production. When that happens, the muscle turns off like a light switch. When larger amounts of carnosine are present in muscle, however, it neutralizes the excess hydrogen ions, increasing exercise efficiency and enabling you to train harder and longer before muscle failure hits.
Carnosine also offers a number of other health benefits. It provides antioxidant activity, particularly in the brain. That’s important because the large concentration of polyunsaturated fats in the brain are subject to oxidation, which can eventually lead to neurodegenerative diseases, such as Alzheimer’s and Parkinson’s.
In addition, by increasing calcium sensitivity, carnosine plays a role in inducing muscular contraction. When carnosine is broken down after contact with the enzyme carnosinase, which is found in most tissues of the body but not muscle, beta-alanine and histidine are freed in the blood. Histidine is used for the production of histamine, which plays an important role in wound healing.
Carnosine also provides anti-aging effects by inhibiting a process called advanced glycation, in which sugars are abnormally deposited into protein structures, thereby weakening them. That’s particularly evident in connective tissue, such as tendons and ligaments.
As noted, the best natural food source of carnosine is meat. Most people who eat meat regularly take in 50 to 300 milligrams of carnosine a day, depending on the quantity of meat. If you eat 100 grams of turkey—or about three ounces—you get 500 milligrams of carnosine. As expected, those who avoid meat, such as vegetarians, have lower carnosine stores in their bodies. One recent study found that vegetarians have 22 percent lower muscle carnosine than meat eaters.
Carnosine supplements do exist, but they are quite expensive. Plus, you have to consider the ubiquitous enzyme carnosinase, which rapidly degrades carnosine in every tissue of the body except muscle. From an exercise standpoint, you would want carnosine to exist mainly in muscle to take advantage of its potent buffering activity. Taking a beta-alanine supplement turns out to be an ideal way to accomplish that goal. Note that when it comes to increasing the carnosine content of muscle, beta-alanine is the important ingredient, not histidine, since muscle is already loaded with histidine.
Studies published six years ago showed that taking three to six grams of beta-alanine daily led to a 40 to 65 percent increase in muscle carnosine. Other studies clearly showed that the increase in muscle carnosine that results from beta-alanine supplementation significantly boosts exercise intensity. Although athletes, including bodybuilders, tend to have larger stores of carnosine in their muscles, they nonetheless are also able to increase them through beta-alanine supplementation.
Similar to what has happened with creatine, discovering the precise optimal way to supplement with beta-alanine has been an ongoing process.One example of that is a common side effect associated with beta-alanine called paresthesia, which is characterized by a pins-and-needles feeling in the skin shortly after taking a dose of beta-alanine. It is thought to be brought on by an excessive stimulation of superficial nerves in the skin. Paresthesia most often occurs when larger doses of beta-alanine are taken, more than 800 milligrams. The extent of discomfort varies, with some people reporting no feelings at all. It usually lasts about 20 minutes, the same length of time as the famed “niacin flush” that occurs when large doses of the B-complex vitamin niacin are taken. One remedy for this rather uncomfortable effect is to take smaller doses of beta-alanine, 800 milligrams, about eight times a day to equal 6.4 grams. Another recent option is to use a time-released form of beta-alanine, which may reduce the skin-prickling effect.
A recent study noted the dearth of information related to the optimal dosages for beta-alanine use.1 Thirty-one young men were randomly assigned to one of three groups:
1) High-low: a high dose (3.2 grams daily) for four weeks, followed by a low dose (1.6 grams) for four weeks, followed by no beta-alanine for another eight weeks
2) Low-Low: 1.6 grams for eight weeks, followed by no beta-alanine for another eight weeks
3) Placebo: no beta-alanine for eight weeks.
Muscular carnosine was monitored by magnetic resonance imaging before and throughout the 16-week study. The most interesting finding was that in relation to muscle carnosine stores, it isn’t the daily dose of beta-alanine that’s important but how long you use it. The longer you use beta-alanine, the more carnosine you’ll have in your muscle. Taking just 1.6 grams a day resulted in a significant increase in muscle carnosine after just two weeks
How much carnosine you already have in your muscle or the muscle type—slow vs. fast-twitch muscle fibers—doesn’t make any difference. Previous studies had suggested that carnosine was preferentially stored in fast-twitch fibers. Indeed, sprinters, who have more fast-twitch fibers have far more muscle carnosine than long-distance runners, who rely on slow-twitch muscle fibers. And unlike the situation with creatine, where having a lot stored in muscle leads to less creatine uptake, the size of existing carnosine stores does not influence how much more they can be increased with beta-alanine supplements.
Another difference between carnosine and creatine is that if you stop using a creatine supplement, muscle stores gradually diminish over a four-week period. Not so with carnosine. Once the muscle is filled up with carnosine (and no one yet knows how much carnosine muscles can store), it stays filled for 15 to 20 weeks, even if you stop taking beta-alanine.
Incidentally, beta-alanine doesn’t interfere with the uptake of creatine into muscle either. If anything, it would be highly synergistic with creatine, since creatine also provides some muscle-buffering action in addition to energy production, both of which would augment beta-alanine activity.
The lessons learned from this study are that you don’t need to take larger daily doses of beta-alanine to increase muscle carnosine; you can achieve that with just 1.6 grams a day long-term. Since there is no depression of muscle beta-alanine transport with continuous use, you don’t have to cycle it, as you do with creatine. Taking smaller doses of beta-alanine will prevent the pins-and-needles skin effect produced by larger doses, or you can try a time-released form. In addition, studies have noted no adverse changes in blood chemistry even after prolonged beta-alanine use, so toxicity isn’t an issue, either.
Using beta-alanine may also provide some brain benefits, according to a recent mouse-based study.2 The researchers found that giving the mice beta-alanine significantly reduced anxiety (what does a mouse worry about, cats?) and also boosted levels of brain-derived neurotrophic factor, which acts in the brain to stimulate neuron growth and repair. BDNF is also stimulated by exercise, and using beta-alanine in conjunction with exercise may have an adjunctive effect. Beta-alanine boosted carnosine levels in the brain, particularly in the hippocampus, the area of the brain involved in learning and memory. In that respect, beta-alanine may turn out to be a “smart nutrient.”
1 Stellingwerff, T., et al. (2011). Effect of two beta-alanine dosing protocols on muscle carnosine synthesis and washout. Amino Acids. 42:2461-2472.
2 Murakami, T., et al. (2010). The impact of taurine and beta alanine-supplemented diets on behavioral and neurochemical parameters in mice: antidepressant versus anxiolytic-like effects. Amino acids. 38:427-34.