Glutamine is essential in protein metabolism, where it plays a number of roles, including the transport and donation of nitrogen-containing molecules, which are essential for building of new muscle. It also plays a role in the detoxification of waste products in the body, can support the immune system, and research shows it may boost levels of Human Growth Hormone (HGH) by stimulating the anterior pituitary gland.
Glutamine is the most abundant free amino acid in the muscle tissue, and it is easily depleted during strenuous exercise. For these reasons, it is one of the amino acids most commonly supplemented by strength athletes and people looking to maintain or build their muscle mass.
Glutamine is one of the non-essential amino acids that can be produced by our bodies. It is also eaten in foods that contain protein. Like many natural supplements, glutamine is very safe, but in some people, it may cause side effects.
Glutamine Side Effects - Constipation
Like muscle cells, cells of the intestine are known to very readily absorb glutamine. Glutamine plays a role in protein synthesis and the absorption of ions and water by the cells of the gut wall. There is research that suggests glutamine may be a treatment for some conditions affecting the stomach and intestine, including gastric ulcers and irritable bowel syndrome. In people without underlying disease, glutamine supplementation is very occasionanally noted to have an effect on the bowel. Constipation is the most common side effect noted with glutamine use, but some people may also experience diarrhoea, nausea or dry mouth (1). Side effects generally subside as the body adjusts to the supplement, but if these are severe or become worse it is advised to stop taking the supplement and consult a medical professional.
Glutamine Side Effects - Headache
Headaches are very occasionally reported as a side effect of glutamine supplementation. Glutamine is able to cross the blood-brain barrier, and it is the precursor molecule to the neurotransmitter GABA, which condusts messages throughout the nervous system. In spite of this connection, there is no reason that glutamine supplementation at a reasonable dosage should cause any increased risk of headache. Although they are similar, it is important not to confuse glutamine with monosodium glutamate (MSG), a dietary additive that may cause headaches in people who are sensitive to this substance.
Glutamine Side Effects and Benefits - Bodybuilding
The uses of glutamine supplementation go far beyond bodybuilding. Research has shown that a high level of glutamine in the body is able to create an environment that is favourable to growth and repair. Because of these properties, Glutamine supplements are often prescribed by doctors in the treatment of muscle wasting syndromes or significant wounds, such as in cancer patients and burn victims (2). Glutamine has positive effects in preserving body mass and the acceleration of healing.
These side effects are known to most strength athletes – the maintenance of an anabolic state in the body is hugely advantageous to those people trying to gain muscle. The bodybuilding community has benifited as a side effect of research into glutamine as a therapeutic aid.
Glutamine Side Effects - Men and Women
Glutamine is safe for both men and women to take. There is no evidence to show that glutamine has any effect on the sex hormones, and it is used by doctors to treat conditions such as muscle wasting and gastric disease in both men and women.
Glutamine Powder Side Effects
In spite of the relative safety of this substance, it is important to note that people with any underlying condition should consult a medical professional before undertaking any change to their diet, including the use of glutamine supplements. This is particularly the case for those with liver and kidney disease, diabetes, or cancer, as glutamine has been known to interfere with these conditions. In certain seizure-prone people, glutamine may be a trigger, and people with Crohn's disease are advised to avoid glutamine, as it can make symptoms worse.
Like many supplements that are regularly consumed in food, glutamine is an extremely safe substance to take for the vast majority, with mild side effects that are experienced by very few people. 3-5g per day is a standard dose for someone looking to increase muscle mass, but up to three times this amount may be safely consumed.
(1) Rhoads M. Glutamine signaling in intestinal cells. JPEN J Parenter Enteral Nutr. 1999 Sep-Oct;23(5 Suppl):S38-40.
(2) Miller AL. Therapeutic considerations of L-glutamine: a review of the literature. Altern Med Rev. 1999 Aug;4(4):239-48.