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Glycine vs Vitamin B12 — Which Should You Take?

Glycine

amino acids

Typically £8–£25/month

Vitamin B12

vitamins

Typically £8–£25/month
Feature
Glycine
Vitamin B12
Typical Dosage
3-5g daily
500-1,000mcg daily
Best Form
Powder
Methylcobalamin
Key Benefits
6 listed
5 listed
Evidence Rating
★★★★
★★★★
Best Time
Evening for sleep benefits; anytime for general health
Morning — may be energising
Upper Limit
10g daily
No established upper limit (water-soluble)
Side Effects
3 noted
2 noted

Glycine Benefits

Improves sleep quality and sleep onset
Supports collagen formation and joint health
Enhances cognitive function and memory
Reduces muscle wasting and supports muscle recovery
Promotes relaxation and reduces anxiety
Supports immune function

Vitamin B12 Benefits

Energy production
Nerve function and protection
Red blood cell formation
DNA synthesis
May reduce homocysteine levels

Glycine Side Effects

Mild gastrointestinal upset at high doses
Drowsiness (particularly at evening dosing)
Fatigue in some individuals

Vitamin B12 Side Effects

Very safe — excess excreted in urine
Rare: acne at very high doses in some individuals

Can You Take Glycine and Vitamin B12 Together?

In most cases, Glycine and Vitamin B12 can be taken together safely. However, always check the interactions section of each supplement and consult a healthcare professional if you take medication or have existing health conditions.

Glycine: May potentiate sedative effects with benzodiazepines or sleep medications

Glycine: Possible interaction with antipsychotic medications

Vitamin B12: Metformin reduces B12 absorption — supplement if on metformin

Vitamin B12: Proton pump inhibitors (PPIs) reduce absorption

Which Should You Choose?

Choose Glycine if your primary goal is: improves sleep quality and sleep onset. Choose Vitamin B12 if your primary goal is: energy production.

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Frequently Asked Questions

Is Glycine better than Vitamin B12?

It depends on your goals. Glycine and Vitamin B12 serve different purposes and are often taken together.

Can I take Glycine and Vitamin B12 together?

In most cases, yes. Glycine and Vitamin B12 can be taken together safely. However, always check for specific interactions and consult a healthcare professional if you take medication.

What is the best time to take Glycine?

Evening for sleep benefits; anytime for general health

What is the best time to take Vitamin B12?

Morning — may be energising

What are the side effects of Glycine?

Mild gastrointestinal upset at high doses. Drowsiness (particularly at evening dosing). Fatigue in some individuals.

What are the side effects of Vitamin B12?

Very safe — excess excreted in urine. Rare: acne at very high doses in some individuals.

How We Compare Supplements

This comparison is based on published clinical research, peer-reviewed studies from PubMed, and established nutritional science. We evaluate dosages based on clinically-effective amounts, not manufacturer recommendations. Benefits listed have at least moderate evidence from human studies. When evidence is limited or conflicting, we note this.

Disclaimer: This comparison is for educational purposes only and is not medical advice. Always consult a qualified healthcare professional before starting any supplement, especially if you take medication or have existing health conditions.

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