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Summary
Vitamin D3 supports calcium homeostasis, immune function, and neuromuscular health; vitamin K2 (MK‑7) helps direct calcium to bones and away from soft tissues. In adults, optimizing 25(OH)D may support mood, sleep, and general cognitive function in low‑status individuals.
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Vitamin D + K2 Liquid — Thorne
A convenient combination of vitamin D and vitamin K that supports bone, cardiovascular, and immune health. NSF Certified for Sport®.
Mental Clarity, Focus, and Energy
- Mood and cognition: RCTs and meta‑analyses suggest small benefits in mood and fatigue primarily when baseline vitamin D is insufficient.
- Energy: Improvements are indirect via sleep, mood, and neuromuscular function rather than stimulant effects.
- Moderators: Baseline 25(OH)D level, dose, duration (≥8–12 weeks), and co‑nutrients (magnesium, omega‑3s) influence outcomes.
Brain Health
- Mechanisms: Vitamin D receptors in brain regions modulate neurotrophic factors and inflammation; K2 partners with D for calcium handling, indirectly supporting vascular and neural health.
- Human data favor benefits in low‑status cohorts; disease‑modifying effects are unproven.
Gut Health
- Indirect: Adequate vitamin D status supports mucosal immunity; GI tolerability of D3+K2 is generally good when taken with food.
Brain-Gut Axis
- By modulating immune tone and sleep, D3+K2 may reduce stress‑related gut–brain signaling. Direct axis trials are limited.
Evidence Summary
Benefit Area | Evidence Quality | Effect Noted | Notes |
Mental Clarity | Limited–Moderate | Small gains in low vitamin D | Test and personalize |
Focus Enhancement | Limited | Indirect via sleep/mood | Baseline dependent |
Energy Support | Limited–Moderate | Reduced fatigue in low‑status cohorts | ≥8–12 weeks |
Brain Health | Moderate | Neuro‑immune and calcium handling | Mixed endpoints |
Gut Health | Limited–Emerging | Mucosal immunity support | Indirect |
Brain–Gut Optimization | Emerging | Stress and sleep pathways | Limited direct trials |
Typical Dosing Instructions
- Standard dose: D3 1,000–2,000 IU/day for maintenance; personalize to blood levels. K2 MK‑7 90–120 mcg/day commonly paired.
- Timing: With a fat‑containing meal to improve absorption
- Notes: Recheck 25(OH)D after ~8–12 weeks; co‑nutrients magnesium and omega‑3s may support response
Safety Considerations
- General safety: Generally safe at common doses
- Common effects: Minimal when taken with food
- Contraindications and cautions: Monitor calcium with thiazide diuretics or hypercalcemia; K2 can interact with warfarin (vitamin K antagonist)
- Populations: Widely used in pregnancy with clinician guidance; individualize dose
- Monitoring: Track 25(OH)D, calcium if indicated, mood, sleep, and energy
References
- Vitamin D supplementation and depression in adults: systematic review and meta‑analysis of randomized controlled trials, Critical Reviews in Food Science and Nutrition, 2022-09-12
- Vitamin D and depressive symptoms: a network meta‑analysis of 41 randomized controlled trials, Nutrition, 2022-08-01
- Vitamin D Fact Sheet for Health Professionals, NIH Office of Dietary Supplements, 2025-09-25
- Vitamin K and cardiovascular health: evidence and controversies, Nutrition, Metabolism & Cardiovascular Diseases, 2022-04-01