For supplement connoisseurs, beta-alanine and carnosine have a relationship worth exploring. Carnosine helps you reach peak performance during high-intensity exercise, and beta-alanine helps boost carnosine levels in muscle. With all the marketing claims of beta-alanine supplements and carnosine supplements, there’s quite a bit of confusion in between. Let’s set the beta-alanine and carnosine record straight.
Beta-Alanine and Carnosine’s Relationship
Beta-alanine (also known as b-alanine, β-alanine, and a carnosine precursor) is an amino acid produced in the liver. It differs structurally (but not chemically) from its more abundant counterpart L-alpha-alanine.
L-alpha-alanine is one of the most abundant nonessential amino acids in the body. L-alpha-alanine serves as a constituent of almost all proteins in the body and plays an important role in shuttling nitrogen—released as a byproduct of amino acid degradation in muscle—to the liver. The liver then incorporates some of the L-alpha-alanine into proteins, and the leftover L-alpha-alanine serves as a precursor for the production of urea, which is then excreted in urine.
In contrast to L-alpha-alanine, beta-alanine is not credited with serving any direct role in the body. Beta-alanine is neither a component of body protein nor does it play a role in metabolic regulation (the process by which our cells regulate every chemical process required for life). The principal role of beta-alanine is to combine with the amino acid histidine to form the peptide carnosine. Benefits of beta-alanine on exercise performance are attributed to its role in the production of carnosine in muscle.
What Science Tells Us About Carnosine
Found in abundance in meat, poultry, and fish, carnosine (sometimes referred to as L-carnosine) is a dipeptide composed of two amino acids, beta-alanine and L-histidine, hooked together. A non-enzymatic free radical scavenger and natural antioxidant, carnosine mainly hangs out in muscle and brain.
Carnosine acts to reduce the rate of formation of a variety of substances that can be factors in the development or exacerbation of diseases including diabetes, atherosclerosis, chronic renal failure, and Alzheimer’s disease.
Researchers have found that carnosine can be particularly helpful when it comes to preventing damage caused by excessively high levels of sugar in the body. Both glucose and fructose molecules can bind with proteins, a process known as glycosylation. Not only does this damage the protein molecules, but it also stimulates inflammatory processes throughout the body. In fact, the glycosylation of protein is one of the four major destructive pathways activated by oxidative stress.
The metabolic effects of carnosine have contributed to its reputation as an “anti-aging” nutrient. As with other anti-aging compounds, carnosine levels decline with age. However, your carnosine intake affects the levels of carnosine in your muscle cells and throughout your body more than any other factor, including your age.
How Carnosine Impacts Exercise
We’ve known for more than 50 years that carnosine functions as a buffer against acid produced in muscles during high-intensity exercise. The importance of carnosine as a buffer is debated, but there is a consensus that increasing muscle carnosine concentrations improves exercise performance during high-intensity activities. It is important, however, to understand the relationship between acid/base balance and exercise in order to appreciate the limit of circumstances in which carnosine in both Type 1 and Type 2 muscle fibers extends its benefits.
When you engage in high-intensity exercise, hydrogen ions begin to accumulate in your muscle fibers. This leads to an increase in acid production and drop in intramuscular pH, which adversely impacts your performance.
Can you recall the burning sensation you feel in your muscles when you sprint? The feeling that tells you it will be impossible to sustain that level of exertion for longer than a few minutes? That's the result of lactic acid accumulation.
If lactic acid were to build up in exercises of the non-high-intensity variety, such as endurance sports, there would be no endurance athletes, as a buildup of lactic acid cannot be sustained beyond a short period of time. A consequence of this effect is that even competitive endurance exercise is performed below the “lactic acid threshold,” or the level of exercise intensity that can be performed without any buildup of lactic acid. For example, lactic acid levels remain close to the minimal level throughout a marathon. The action of carnosine on buffering acid production in muscle can, therefore, only be expected to be of significant benefit during high-intensity exercise. This may be why the body innately produces higher concentrations of carnosine in the fast-twitch, Type 2 muscle fibers that power you through rapid, explosive movements.
Research indicates that boosting muscle carnosine synthesis can reduce the acidity in active muscles during high-intensity exercise. A Belgian research team examined how muscle carnosine content affects fatigue experienced by trained sprinters during repeated isokinetic contraction bouts. Their placebo-controlled, double-blind study found that increased levels of carnosine significantly decreased fatigue during repeated bouts of exhaustive dynamic contractions.
In addition to its buffering capacity, carnosine has several other physiological effects that can improve your athletic performance.
As I stated earlier, carnosine has impressive antioxidant properties. Levels of a type of free radical called reactive oxygen species (ROS) can spike during exercise, which some believe may increase muscle fatigue. Carnosine can help to flush those free radicals from your muscles, which may lower fatigue levels.
Carnosine also influences enzyme regulation related to activation of myosin ATPase your body uses to maintain ATP stores. As you may know, your body generates energy from its ATP (adenosine triphosphate) stores.
Research-Backed Benefits of Beta-Alanine
The primary focus of research conducted to date on beta-alanine supplementation has been the effect of beta-alanine on physical performance and body composition.
The effect of beta-alanine supplementation on muscular endurance has the most research behind it. At least eight high-quality studies have shown that beta-alanine can lead to a significant increase in muscular endurance.
According to a double-blind trial published in Amino Acids, a peer-reviewed journal, after 28 days of beta-alanine supplementation, participants experienced less muscle fatigue and had a greater workload capacity at peak exhaustion.
The beneficial effects of beta-alanine supplementation on power output have also been well-documented. The authors of a study published in the International Journal of Sports Medicine had participants complete a resistance-training program while taking 4.8 grams of beta-alanine daily for 30 days. They found that this level of beta-alanine supplementation resulted in impressive gains as measured both by power output and work volume. One particularly indicative finding: at the end of the trial, participants who supplemented with beta-alanine could perform 22% more repetitions at 70% of their one-repetition maximum than those in the placebo group.
Beta-alanine can also influence your body composition by encouraging fat loss and stimulating muscle growth.
According to a double-blind, placebo-controlled study conducted by researchers from the Human Performance and Physical Education Department at Adams State College in Colorado, beta-alanine supplementation can lead to the loss of fat mass without accompanying decreases to muscle mass.
The authors of a separate double-blind trial looked at the results of combining beta-alanine supplementation with high-intensity exercise. Participants who supplemented with beta-alanine while engaged in 6 weeks of high-intensity interval training benefited from a number of improvements that the placebo group who carried out the same training regimen did not, including increased lean body mass.
Beta-alanine supplementation can also enhance your anaerobic capacity, which has major implications for endurance performance. When you run, swim, cycle, or carry out any other form of aerobic exercise at a fast speed for a long enough period of time, your body will reach a point at which it's consuming the maximum amount of oxygen it can. This is the moment when your anaerobic capacity comes into play. The greater the capacity of your muscles to work anaerobically—without the addition of more oxygen—the faster and longer you'll be able to sustain that pace.
Findings published in Medicine & Science in Sports & Exercise and elsewhere have shown that beta alanine supplementation can positively affect your anaerobic capacity. This effect appears to stem from improved muscular endurance and reduced fatigue rather than cardiopulmonary interactions.
A number of studies have found that beta-alanine can help you exert yourself at a higher rate for longer periods of time while preventing fatigue. One study published in Nutrition Research showed that beta-alanine supplementation can lead to measurable decreases in fatigue rates, particularly when participants were working at maximum capacity. Subjective feelings of soreness and fatigue were also lower for the participants taking beta-alanine supplements than for those in the placebo group.
A separate double-blind, placebo-controlled study specifically examined how beta-alanine affects neuromuscular fatigue. The study's authors enrolled participants with an average age of approximately 73, since the aging process depletes skeletal muscle carnosine content, which has been linked to a reduced muscular buffering capacity that then results in increased rates of fatigue. The authors found that beta-alanine markedly delayed the onset of neuromuscular fatigue and led to significant increases—28.6%—to participants' physical working capacity at the fatigue threshold.
The Pros and Cons of Carnosine Supplements
Carnosine supplements are available from a variety of sources and marketed as being able to slow the aging process and help prevent and treat complications of diabetes. Carnosine supplementation is also advocated as a treatment for cardiometabolic health and cognitive function.
Despite the multitude of beneficial effects credited to carnosine in the body, there are limitations to its value as a nutritional supplement. Orally ingested carnosine is rapidly broken down to its component amino acids (beta-alanine and histidine). Plus, scientists have repeatedly found evidence of poor intestinal absorption of carnosine. For example, one study found large amounts of carnosine—up to 14% of the ingested dose—in participants' urine 5 hours after they had ingested it.
Furthermore, a diet of beef, pork, and chicken is rich in carnosine, and the amount of carnosine recommended for a dietary supplement (1 gram per day) adds an insignificant amount to the total daily intake for meat eaters. Therefore, carnosine supplementation is not an effective way to increase the amount of carnosine in muscle. In the case of a vegetarian diet, carnosine supplementation may play a more prominent role in maintaining carnosine concentration in muscle.
Why Most People Benefit More from Beta-Alanine Supplements
The production of carnosine in muscle is limited by the availability of beta-alanine. As a result, dietary supplementation with beta-alanine is advocated as the most effective way to increase carnosine levels in muscle. The International Society of Sports Nutrition has issued a position statement on the effectiveness of beta-alanine as a nutritional supplement to raise muscle carnosine levels. The highlights of this report are as follows:
- Four weeks of consuming 4-6 grams of beta-alanine daily significantly increases muscle carnosine levels.
- Beta-alanine supplements appear to be safe.
- Tingling is the only reported side effect.
- Daily supplementation with 4-6 grams of beta-alanine improves high-intensity exercise performance in events lasting 1-4 minutes.
- Daily supplementation with beta-alanine may reduce the impact of neuromuscular fatigue in older subjects.
- Combining beta-alanine supplements with other supplements (such as essential amino acids) may be beneficial.
Carnosine Supplementation vs. Beta Alanine Supplementation: The Bottom Line
Carnosine can act as a buffer in muscle, thereby lessening the effects of excess acidity resulting from high-intensity exercise. This effect can improve high-intensity exercise performance but is unlikely to have much effect on endurance exercise. Other beneficial effects have been proposed (although not proven). Carnosine supplementation is ineffective in increasing the amount of carnosine in muscle because it is broken down to its constituent amino acids before tissue uptake can occur.
Beta-alanine is not known to have any direct physiological role but is the rate-limiting factor for carnosine synthesis. Studies have shown that beta-alanine supplementation can increase muscle carnosine content, and therefore, the buffering capacity of your muscles. This can result in significant improvements to physical performance as well as body composition.
If you're seeking to benefit from increased concentrations of carnosine, supplementing with carnosine itself is not the best way to achieve that goal. Instead, you'll see far more profound effects from beta-alanine supplementation.