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Vitamin K2 MK-4 vs Vitamin D3 — Which Should You Take?

Vitamin K2 MK-4

vitamins

Typically £8–£25/month

Vitamin D3

vitamins

Typically £8–£25/month
Feature
Vitamin K2 MK-4
Vitamin D3
Typical Dosage
45-180 mcg daily
1,000-4,000 IU daily
Best Form
MK-4 powder
Cholecalciferol (D3)
Key Benefits
5 listed
5 listed
Evidence Rating
★★★★
★★★★★
Best Time
With fat-containing meals for optimal absorption
With a fat-containing meal for best absorption
Upper Limit
360 mcg daily
10,000 IU daily (short-term)
Side Effects
3 noted
3 noted

Vitamin K2 MK-4 Benefits

Supports bone mineralisation and density
Promotes arterial flexibility and cardiovascular health
Activates osteocalcin for bone matrix formation
May reduce calcification of soft tissues
Supports dental health and enamel formation

Vitamin D3 Benefits

Bone health and calcium absorption
Immune system support
Mood regulation and mental health
Muscle function
May reduce risk of respiratory infections

Vitamin K2 MK-4 Side Effects

Generally well-tolerated with minimal adverse effects reported
Rare reports of mild gastrointestinal upset at high doses
No toxicity established at supplemental levels

Vitamin D3 Side Effects

Rare at normal doses
Hypercalcemia at very high doses (>10,000 IU/day long-term)
Nausea, vomiting if severely overdosed

Can You Take Vitamin K2 MK-4 and Vitamin D3 Together?

In most cases, Vitamin K2 MK-4 and Vitamin D3 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.

Vitamin K2 MK-4: May interact with warfarin and other anticoagulants; maintain consistent intake

Vitamin K2 MK-4: Requires adequate fat intake for proper absorption

Vitamin D3: Increases calcium absorption — monitor with calcium supplements

Vitamin D3: May interact with thiazide diuretics

Which Should You Choose?

Choose Vitamin K2 MK-4 if your primary goal is: supports bone mineralisation and density. Choose Vitamin D3 if your primary goal is: bone health and calcium absorption.

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Frequently Asked Questions

Is Vitamin K2 MK-4 better than Vitamin D3?

It depends on your goals. Vitamin K2 MK-4 and Vitamin D3 serve different purposes and are often taken together.

Can I take Vitamin K2 MK-4 and Vitamin D3 together?

In most cases, yes. Vitamin K2 MK-4 and Vitamin D3 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 Vitamin K2 MK-4?

With fat-containing meals for optimal absorption

What is the best time to take Vitamin D3?

With a fat-containing meal for best absorption

What are the side effects of Vitamin K2 MK-4?

Generally well-tolerated with minimal adverse effects reported. Rare reports of mild gastrointestinal upset at high doses. No toxicity established at supplemental levels.

What are the side effects of Vitamin D3?

Rare at normal doses. Hypercalcemia at very high doses (>10,000 IU/day long-term). Nausea, vomiting if severely overdosed.

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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