Whey protein is widely extolled as a rich source of the amino acids needed to pack on muscle. Gym rats are drawn to creatine like paparazzi to a Sunset Strip nightclub for its tendency to boost strength. Even something as seemingly nonsplashy as fish oil has been hailed as a super-supplement of late because of its rich array of health-boosting properties.
With these supplements hogging all the headlines, it’s easy to forget that glutamine is one heck of a rock star when it comes to chiseling out an impressive physique, with fat-fighting, immunity-boosting, recovery-enhancing benefits galore.
Under couch-potato conditions, the body produces all the glutamine it needs. However, if you’re prone to putting your body under the rigors of amped-up workouts, you can likely benefit from supplementation, says Shawn M. Talbott, Ph.D., a nutritional biochemist and co-author of The Cortisol Connection (Hunter House, 2002). From hastening muscle recovery to bolstering immune health, here are five reasons why this under-the-radar amino acid should be part of your supplement arsenal.
When you’re training hard, lactic acid builds up, creating an acidic environment that leads to muscle fatigue. A study conducted at Louisiana State University School of Medicine suggests that glutamine may help you overcome this effect.
The scientists discovered that subjects who consumed 2 grams of glutamine had higher blood levels of bicarbonate 90 minutes after intake. (Bicarbonate is a chemical buffer that keeps the pH of the blood from becoming too acidic.) In practice then, glutamine supplementation may lessen the “burn” incurred by higher levels of lactic acid accumulation, helping power you up that mountain or pound out more reps per set to stimulate muscle growth. It’s also important to note that protein breakdown is accelerated under acidic conditions, so dampening acidity impedes muscle catabolism. The same study also reported higher circulating levels of growth hormones induced by glutamine supplementation, another bodybuilding bonus.
Further proving that glutamine may keep your engines revved longer, a 2008 study published in the British Journal of Sports Medicine reported that soccer players who were given glutamine reduced their accumulation of blood ammonia during prolonged, strenuous exercise. Ammonia is an acidic compound produced when amino acids are used to generate energy, and its buildup can provoke exercise fatigue. Whether heading to the field or the gym, glutamine seems to be a good supplement to have in your arsenal.
Supplementing with glutamine may help you rev up your metabolism and whittle your belly. Scientists at Iowa State University discovered that subjects who took glutamine with a meal burned off more calories, carbohydrates and fat afterward than those who were not given this amino acid.
Glutamine appears to stimulate insulin secretion ,which drives nutrients into cells for energy production. Moreover, glutamine may also help the Krebs cycle — a series of reactions in which carbs and fat are turned into energy — run more efficiently.
Prevent Muscle Breakdown
Because skeletal muscle is the primary reservoir of glutamine, prolonged shortcomings in plasma glutamine could lead to a significant loss of muscle mass — not good if gaining premium mass is your goal. “When plasma glutamine levels fall in response to exercise, muscle tissue can enter a state of catabolism to provide free glutamine for the immune system and other parts of the body,” Talbott says.
In fact, studies have found there to be a decline in muscle glutamine postworkout. “So supplementing with glutamine could provide cells with a supply that does not need to be harvested from skeletal muscle,” Talbot explains.
Recover More Rapidly
Proper recovery from exercise is a critical component of overall fitness, and it seems glutamine can assist your weary muscles. In a study published in Medicine & Science in Sports & Exercise, male volunteers between the ages of 19 and 30 underwent an exhaustive bout of cycling exercise and then took either glutamine (0.3 grams per kilogram of bodyweight) or a placebo for six days. After six days, the exercise test was repeated, with the glutamine group demonstrating more power and endurance than the placebo group. Based on the results, the authors concluded that glutamine helps accelerate muscle recovery from intense activity.
One way glutamine may hasten recovery is through its stimulation of glycogen synthase, an enzyme necessary for the storage of glycogen in the muscles and liver. Glycogen is a storage form of carbohydrate that serves as the primary fuel for high-intensity exercise — the more you have, the harder you can run and the more iron you can hoist.
Furthermore, a 2009 Brazilian study discovered that animals that were given glutamine had lower levels of compounds indicative of muscle inflammation and damage — both of which can stymie proper recovery — in response to exercise than those that did not receive supplementation.
Boost Your Health
As the most abundant amino acid in the body, one of glutamine’s primary responsibilities is to provide fuel to immune cells so they can safeguard against infections, Talbott says. In situations of stress, such as clinical trauma or starvation, he says the concentration of glutamine in the blood is decreased, often substantially. “The added stress of intense exercise training also results in well-established post-exercise glutamine depletion because the immune cells suck up the glutamine to handle the workload,” he says.
This may explain why bouts of strenuous exercise such as marathon running and heavy weight training are often associated with immune suppression and, in turn, an increased risk of infections such as a cold or the flu. “Therefore, glutamine supplementation may lift your immune system out of its suppressed state,” Talbot adds. The upshot is that taking glutamine can help keep you out of the Kleenex box so you can spend more time in the gym.
A 2009 study in the European Journal of Applied Physiology found that glutamine supplementation increases the functioning of macrophages (a type of white blood cell that is a key player in the immune response to infectious microorganisms) post-exercise, lending credence to glutamine’s immune-boosting capabilities. There is also increasing evidence that glutamine helps prevent the exercise-induced destruction of neutrophils, other white blood cells that seek out and destroy infection-causing foreign invaders.
Considered together, these five benefits lead to one conclusion — if you’re a bodybuilder or athlete who wants to cover all your nutritional bases, glutamine is a must-have supplement, one that can truly affect your results. And that’s a headline that writes itself.
So how much glutamine do you need? For immune-system support and anti-catabolic actions, Shawn M. Talbott, Ph.D., recommends consuming up to 5 grams of glutamine after exercise. Because glutamine works better in the presence of branched-chain amino acids, he advises mixing it with whey protein (a stellar source of aminos) in a postworkout shake. “Glutamine is very safe and relatively cheap compared to other supplements,” he says. For these reasons, you can also consider adding one or two extra servings during the day, such as once in the morning and once before bed.