Short answer

We found no documented interaction between Glycine and Tribulus terrestris in the sources below. That isn't proof the combination is right for you: check each one's cautions, and ask your pharmacist if you take medication.

Glycine

What it is: An amino acid the body makes; it's a building block of creatine, glutathione and collagen.

What the research says: Some studies suggest it may improve sleep quality and recovery, but reviews say more good human trials are needed.

Cautions

• No major safety concerns are reported at supplement doses; human research is limited.

Medicines to check

• Talk to your clinician if you take any medicine

In Holitro: Glycine (850 mg per capsule)

Sources: PubMed review: An Update of the Promise of Glycine Supplementation (Sports, 2024) (updated September 2024); PubMed review: Multifarious Beneficial Effect of Glycine: A Review (2017) (updated March 2017)

Tribulus terrestris

What it is: A plant sold with claims that it raises testosterone.

What the research says: The few studies on strength or muscle found no benefit.

Cautions

• It hasn't been studied enough to know whether it's safe; high doses damaged the heart, liver and kidneys in animals.
• Sports-medicine experts advise against supplements claimed to boost testosterone.

Medicines to check

• Talk to your clinician if you take any medicine

In Holitro: Tribulus (500 mg per capsule)

Source: NIH Office of Dietary Supplements: Dietary Supplements for Exercise and Athletic Performance (updated March 2021)

Check with your doctor or pharmacist, especially if you take medication.

Check your stack — free

Educational information only, not medical advice. This reflects general ingredient overlap, not a personalized safety review. Always check with your doctor or pharmacist before combining supplements, especially if you take medication, are pregnant or nursing, or manage a health condition. These statements have not been evaluated by the FDA.