Short answer

We found no documented interaction between Biotin and Glycine 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.

Biotin

What it is: A B vitamin that helps turn the food you eat into energy.

What the research says: It's widely sold for hair, skin and nails, but there's little evidence for that. A few small studies found harder nails in people with brittle nails.

Cautions

• High-dose biotin can make some lab tests wrong, including thyroid hormone tests. Tell your clinician before a blood test.

Medicines to check

• Long-term anti-seizure medicines can lower biotin levels

In Holitro: Biotin 5000mcg (5000 mcg per capsule)

Source: NIH Office of Dietary Supplements: Biotin: Fact Sheet for Consumers (updated January 2021)

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)

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.