Vitamin D3 + K2

D3 acts as a steroid hormone — it binds receptors in nearly every cell type and modulates gene expression. The pituitary needs D3 sufficiency to fire normally, which is why GH and testosterone correlate with D3 status. K2 separately activates a protein called osteocalcin that pulls calcium INTO bone, and another called matrix Gla protein that keeps calcium OUT of arteries and soft tissue. D3 raises calcium absorption; without K2, the extra calcium can deposit where you don't want it.

5,000 IU D3 + 90–120 mcg K2 (MK-7) daily, with a fat-containing meal. Re-test serum 25(OH)D after 90 days; target 50–80 ng/mL.

With your largest fat-containing meal of the day (D3 is fat-soluble). Doesn't matter morning or evening. Some users find evening D3 disrupts sleep — if so, switch to morning. K2 (MK-7) has a long half-life so daily dosing is fine.

• Persistent low energy / depressed mood, especially in winter months
• Muscle weakness or aches without clear cause
• Bone aches (deep, achy, not joint pain)
• Low libido or recovery despite good sleep + training
• Frequent colds or slow infection recovery

• Mood lifts within 4–6 weeks (subtle, especially in dark months)
• Energy normalizes
• Recovery from training improves
• Follow-up 25(OH)D test shows movement toward 50–80 ng/mL range

• Megadosing 10,000+ IU without a baseline 25(OH)D test — ~10% of people are slow metabolizers and overshoot
• Skipping K2 — D3 alone raises calcium absorption without telling the body where to put it
• Buying D2 (ergocalciferol) — less effective than D3 (cholecalciferol)
• Stopping after a 'fix' without retesting — D3 status is dynamic with sun exposure and weight