Vitamin D3 and K2 Dosage: How Much Do You Need?
Vitamin D is the most common deficiency. Here’s how to supplement correctly.
For all supplement guides, see: Best Greens Powder.
D3 Dosage Guidelines
| Starting Point | Suggested D3 Dose |
|---|---|
| Deficient (<20 ng/mL) | 5,000-10,000 IU/day initially |
| Insufficient (20-30 ng/mL) | 2,000-5,000 IU/day |
| Maintenance (30+ ng/mL) | 1,000-2,000 IU/day |
| Optimal target | 40-60 ng/mL blood level |
Why Take K2 With D3?
Vitamin D increases calcium absorption. K2 directs that calcium to bones, not arteries.
- D3 alone: More calcium absorption
- K2 function: Activates proteins that put calcium in bones
- Together: Calcium goes where it should
K2 Dosage
| K2 Form | Dose | Notes |
|---|---|---|
| MK-7 | 100-200mcg/day | Preferred (longer half-life) |
| MK-4 | 1,000-5,000mcg/day | Shorter half-life (needs higher dose) |
Recommendation: 100-200mcg MK-7 per 5,000 IU D3.
Combined Products
Easiest approach: buy D3+K2 combo products:
| Product | D3 | K2 | Price |
|---|---|---|---|
| NOW D3+K2 | 5,000 IU | 180mcg MK-7 | ~$20 |
| Thorne D3+K2 | 5,000 IU | 100mcg MK-7 | ~$25 |
| Sports Research D3+K2 | 5,000 IU | 100mcg MK-7 | ~$20 |
Get Your Levels Tested
Don’t guess—test your 25(OH)D blood level:
- At-home tests: $50-70 (Everlywell, LetsGetChecked)
- Doctor ordered: covered by many insurances
Retest after 3 months of supplementation to find your dose.
Timing and Absorption
- With food: D3 is fat-soluble—take with a meal containing fat
- Any time of day: Morning or evening both work
- Consistency: Daily dosing is better than weekly mega-doses
Who Needs More D3
- Northern latitudes (limited sun)
- Dark skin (melanin reduces synthesis)
- Elderly (reduced skin synthesis)
- Indoor workers
- Obese individuals (D3 sequestered in fat)
Upper Limits
- Official UL: 4,000 IU/day
- Research suggests up to 10,000 IU safe for most
- Toxicity rare below 50,000 IU/day long-term
- Monitor blood levels if taking 5,000+ IU
Verdict
Most people: 2,000-5,000 IU D3 + 100-200mcg K2 (MK-7) daily.
Best approach: Get blood level tested, then adjust dose to reach 40-60 ng/mL.
Buy combos: D3+K2 products are convenient and cost-effective.
For all supplement guides, see: Best Greens Powder.