Medically Reviewed by Melinda Ratini, MS, DO on September 01, 2023
2 min read

Glycine is an amino acid, one of 20 used to make proteins in the human body. The body produces it naturally.

Glycine is also found in high-protein foods such as:

  • Meat
  • Fish
  • Dairy products
  • Legumes

It's estimated that we get about 2 grams of glycine a day from food sources. As a supplement, it's taken in much higher amounts.

Glycine has numerous proposed uses. Few of those suggested uses have enough evidence to fully back glycine's effectiveness.

Glycine has shown promise as a part of a treatment plan for schizophrenia. Research is ongoing.

Glycine is also marketed for a host of other uses, despite the lack of scientific evidence that it is effective or safe for any of them. For example, glycine is marketed as a way to:

  • Promote the healing of overworked or damaged muscles.
  • Soothe an upset stomach.
  • Promote calm and relaxation.
  • Boost the immune system.
  • Increase human growth hormone.

Again, there is no reliable evidence that it works for such uses.

Optimal therapeutic doses for glycine have not been set for any condition. Also, as with supplements generally, the quality of the active ingredients in products that contain glycine varies from maker to maker.

High-protein foods provide small amounts of glycine. But supplements are required to get glycine in high doses.

Glycine's safety has not been fully tested or studied. Particular caution should be taken when considering glycine for young children, pregnant or breastfeeding women, and people with liver or kidney disease.

People being treated with clozapine should avoid taking glycine. Also people who have had a stroke should not take glycine without the supervision of a doctor.

A few people have reported nausea, vomiting, and upset stomach after taking glycine. Such reports have been rare, and the symptoms have gone away after glycine was discontinued.