Your eXpert Guide to
Glutamine

Intensive training reduces immune function, recovery and increases muscle breakdown. Studies found this was matched with reduced glutamine levels. Glutamine levels were also lower in those suffering with overtraining³. Studies found that supplementing with glutamine prevented the decrease in glutamine levels and associated effects.

Following the Los Angeles marathon²:

• 12.9% of runners reported upper respiratory tract (URTI) the week after compared with 2.2% in non-runners
• 40% of runners reported URTI in the 2 months before the race

Glutamine is the most abundant amino acid in the body. It can be found in protein foods such as fish, meat and dairy products. Glutamine is non-essential and can be synthesized from the amino acids Glutamic acid, Valine and Isoleucine. Glutamine is an essential fuel for immune system cells⁴. Glutamine also plays a critical role in muscle growth and recovery⁵.

Glutamine can help to boost your immune system, prevent muscle breakdown, improve recovery and aid muscle building

Glutamine has been shown to:

• Prevent reduced immune function
• Improve recovery
• Increase growth hormone

Glutamine should help if you are involved in:

• Intensive weight training
• Triathlons
• Heavy endurance training
• High level games training e.g. football⁶
• Competitive endurance races
• Marathon running²

Glutamine can aid performance in several ways:

Improved immune function

The immune system recognises attacks and destroys infectious agents within the body. Intense exercise increases the release of stress hormones, such as adrenaline and cortisol. Stress hormones may cause a reduction in immune function and glutamine levels⁷. Glutamine is an essential fuel for the immune system cell lymphocytes.

Glutamine supplementation maintains blood glutamine levels to prevent reduced immune function. Studies show glutamine supplementation prevented reduced immunity by producing an 18-fold increase in immune cells⁸. Nutritional deficiencies have also been shown to have immune suppressing properties⁹.

Prevents muscle tissue breakdown

In theory, glutamine prevents muscle tissue breakdown during high resistance training. Glutamine draws water into your muscle cells increasing their volume. This process is known as 'cell volumisation'. By drawing water in, muscle tissue breakdown and the action of stress hormones are prevented.

Improved Recovery

Glutamine improves recovery after exercise by re-fueling your energy stores¹⁵. This is beneficial for endurance athletes when carbohydrates are the main source of energy. Some bodybuilders restrict their carbohydrate intake when cutting body fat and this can benefit them, as restricting carbohydrates will reduce recovery and energy stores. Glutamine speeds the rate at which your energy stores are refuelled enabling you to train again sooner.

Increased growth hormone

Glutamine supplementation after exercise increases growth hormone levels¹⁰. Glutamine increases the levels of the amino acids Arginine and Glutamate, which are also capable of boosting growth hormones. Growth hormones are strong protein anabolic agents that improve nitrogen sparing and protein retention by increasing protein synthesis¹¹. Growth hormone stimulates the breakdown of fat and spares carbohydrate stores.

Glutamine can be mixed with water or added to your post workout meal replacement, protein or creatine drinks.

How much?

Glutamine supplementation after exercise increases growth hormone levels¹⁰

Typical recommended doses suggest that 100mg/kg of body weight during the 2 hours after exercise, is sufficient to raise glutamine levels⁵. To calculate this multiply your body weight in kilograms by 100. Most glutamine supplements suggest a serving size of 5g/day.

When?

The best time to use glutamine is immediately after training, within 2 hours of your workout. This is when your glutamine levels will be at their lowest. You may want to consider using 2 doses if one of the following applies to you:

• If you are in high intensity training
• Are susceptible to sore throats
• Are a vegetarian or eat low amount of glutamine containing foods such as fish, meat or dairy products.
• Tendency to recover slowly

Glutamine supplements are very similar between brands so don't be put off by the large product range. Glutamine products typically come in the form of L-glutamine powder - a white, tasteless, odourless powder that only contains glutamine.

Glutamine can also come in the form of glutamine peptides. The differences are glutamine peptides are pre-digested and bonded with other amino acids to theoretically improve absorption and utilisation. L-glutamine is glutamine in its free form, meaning that it has not been bound to other amino acids. There is no evidence to suggest that one over the other is superior.

Meal replacements and proteins are often fortified with around 2g of glutamine so keep a look out for it if you use these products.

No adverse side effects have been reported with glutamine supplementation.

What else can increase stress and reduce immune function?

Other stressors on the immune system include lack of sleep, severe mental stress, malnutrition and weight loss. A review of research found that 852 endurance athletes in Germany had high incidences of URTI when they also reported feelings of stress and were sleep deprived⁸. Therefore increased stress, that is common to pre competitions were you have to travel and the stress of performance outcome is high may increase the chances of reduced immune function⁹.

Why should you use glutamine within 2 hours of recovery?

For several hours after heavy exertion the immune system experiences suppressed function. Glutamine consumed immediately after a marathon and then again 2 hours later reduced incidences of URTI in the 7 days after the race¹³.

Are there any other supplements that will help prevent illness and injury?

Supplementing with BCAA before endurance exercise prevented 40% of the reduced immune supporting lymphocytes and prevented the drop in plasma glutamine levels that are observed post exercise¹⁴.