In various places, glutamine is sold. My questions are:

What are the side effects, if there are any, of using this product?

What happens while you are taking it?

What happens when you decide to stop taking it?

Thanks in advance,

Dear Orestes,

There are many myths about the Greek figure whose name you share, and similarly, there’s a lot out there about the possible powers of glutamine. While research continues, we do know a few things about it. Glutamine is an amino acid that the cells produce to help the body with a host of different cellular functions such as building muscles and supporting organ systems. Some people may take glutamine supplements to help support these functions. For others a supplement may not be necessary since the amount they need is produced by the body and can be consumed through various dietary sources. Side effects can range from a cough to changes in bowel movements. If you stop taking glutamine, your body will continue to produce this amino acid, although it's best to consult with a health care provider prior to starting or stopping any prescribed medications, including supplements!

Glutamine is one of 20 amino acids and is considered “non-essential", not because it’s not important to your health (it is!), but because your body can synthesize it from food sources and other small molecules. It's one of the most abundant amino acids and is used for an array of cellular and tissue-specific functions. Glutamine helps carry out all cellular processes, moves molecules throughout the body, it contributes to building muscles, and is essential to muscle function. Glutamine also supports various organ systems: it promotes gastrointestinal (GI) health, helps balance the acid and base chemistry of your kidneys and supports the immune system by helping you recover from wounds and illness. Your body can also burn glutamine for energy.

While you mentioned purchasing glutamine, it can also be found in foods like poultry, beef, pork, dairy products (e.g., yogurt, milk, and cottage and ricotta cheeses), and leafy greens (e.g., parsley, spinach, and cabbage)?

Taking glutamine in its supplement form will not lead to any drastic changes, good or bad, for most people. If you end up taking more glutamine than you need, and you don’t have a metabolic condition, your body will likely convert the extra glutamine into something else it can use like other amino acids, glucose for instant fuel, or glycogen or fatty acids for long-term fuel storage. While the risk for adverse side effects is rare, some of the more common side effects of consuming glutamine supplements include coughing, frequent urge to defecate, and straining while pooping. If you’re experiencing symptoms like these you may want to check in with your health care provider.

For some specialized populations, glutamine supplements may be recommended or even prescribed by a health care provider (e.g., those who are critically ill and hospitalized, patients undergoing invasive surgery, some cancer patients, or those who consistently train. In these cases, glutamine supplements have been shown to reduce morbidity, increase the rate of healing, reduce swelling, and possibly even ward off upper respiratory tract infections and reduce muscle recovery time. These groups all share one common denominator: high levels of stress on the body. Therefore, if you haven’t been diagnosed with a life-threatening illness or aren’t training for the Tour de France, you may not see much, if any, change when taking glutamine.

Just as there are groups for whom increased glutamine is recommended, there are a few groups of people who health care providers advise against taking glutamine supplements. For example—children under the age of ten, people with Reye's syndrome, and those living with kidney or liver disease. If you are on any medications or are pregnant or breastfeeding, it’s best to talk with a health care provider before using glutamine.

Before starting or stopping any supplement, it’s wise to speak with a health care provider as they can help determine whether it fits your dietary needs. They may also have specific recommendations for a supplement, as these products are not approved by the Food and Drug Administration prior to being put on the market.

Because your body relies on glutamine to carry out some pretty important functions, if for some reason your glutamine levels get low either because your diet changes or you discontinue a glutamine supplement, your body will supplement this loss by starting to make more of the molecule. In this way, your body creates a buffer system to help make sure you have what you need.

Last updated Feb 24, 2023
Originally published May 20, 2005

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