Loading…
We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Head-to-head evidence comparison — which supplement is right for you?
Calcium wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
18 of 20 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
12 of 15 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Calcium and Vitamin K2 have evidence — compare verdict strength side-by-side.
1000–1200mg daily (split doses)
Split doses with meals, 500mg with breakfast, 500mg with dinner
Calcium Citrate
100-200mcg (MK-7)
With a meal containing fat
MK-7 (menaquinone-7)
Co-supplementation directs calcium into bone while reducing vascular calcification risk. Studies show MK-7 supplementation alongside calcium+D3 improves bone mineral density and carboxylated osteocalcin levels compared to calcium+D3 alone.
Always combine calcium supplementation with vitamin K2 (MK-7 form, 90–180 mcg/day) to optimize bone deposition and reduce arterial calcification risk, particularly in individuals on long-term calcium therapy.
6-24 months
12-36 months
Throughout pregnancy
Within days of starting
6-12 months
1-3 years
Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials.
Food & Function (2020) · Meta analysis · n=12000
Combined calcium and vitamin D significantly improved lumbar spine BMD in postmenopausal women
Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis.
JAMA (2017) · Meta analysis · n=51145
33 trials involving 51,145 participants were analyzed
Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis.
JAMA Network Open (2019) · Meta analysis · n=51419
Meta-analysis of 11 randomized clinical trials with 51,419 participants
Vitamins K2 and D3 Improve Long COVID, Fungal Translocation, and Inflammation: Randomized Controlled Trial
Nutrients (2025) · Rct · n=151
The median age was 46 years; 71% were female and 29% were non-white.
The effect of vitamin K2 supplementation on bone turnover biochemical markers in postmenopausal osteoporosis patients: a systematic review and meta-analysis
Frontiers in endocrinology (2025) · Meta analysis · n=2570
Vitamin K2 (VK2) increased osteocalcin (OC; MD 1.86, 95% CI 1.17-2.56) and bone-specific alkaline phosphatase (BAP; MD 1.49, 95% CI 0.98-2.00).
Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial
JAMA internal medicine (2024) · Rct · n=310
Of the 199 enrolled individuals, 108 (54.3%) were female, and the mean (SD) age was 72.3 (5.5) years.
Based on meta-analysis of 59 RCTs showing 0.6-1.8% BMD increases. Requires vitamin D co-supplementation for optimal effect. Effectiveness plateaus beyond 1200mg daily.
Based on meta-analyses showing 2.17% WMD improvement in lumbar BMD. Effects primarily demonstrated with MK-7 form in postmenopausal women. Combination with vitamin D3 may enhance effects.
AI-estimated from published studies. Interpret as directional guidance.
Calcium has a higher evidence score (8/10 vs 6/10) and wins in 2 of 3 categories.
For bone health, Calcium has a higher relevance score (95 vs 88).
Calcium and Vitamin K2 may work well together: Co-supplementation directs calcium into bone while reducing vascular calcification risk. Studies show MK-7 supplementation alongside calcium+D3 improves bone mineral density and carboxylated osteocalcin levels compared to calcium+D3 alone. Always combine calcium supplementation with vitamin K2 (MK-7 form, 90–180 mcg/day) to optimize bone deposition and reduce arterial calcification risk, particularly in individuals on long-term calcium therapy.