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Vitamins & minerals · FROM DR. PURSER’S TEACHING

Vitamin D

Helps calcium absorption and bone mineralization.

Based on teaching by Dan Purser, MD. How we prepare these guides

Updated Sep 23, 2026 · Educational reference

THE TEACHING CONNECTION

A nutrient level and a receptor gene answer different questions

A nutrient level and a receptor gene answer different questions

Dr. Purser places vitamin D in immune, hormone and bone-related teaching. The conversion-genetics chapter includes VDR, which concerns the vitamin D receptor. This is distinct from measuring a vitamin D blood level.

Putting the pieces together

Vitamin D comes in different forms and may already be in products you use. Review your intake and relevant blood results together. A VDR variant does not by itself prove a deficiency or set a dose.

How supplementation is approached

Dr. Purser’s plan reviews vitamin D as a fat-soluble nutrient and separates a VDR gene finding from the measured vitamin D level. His course schedules vitamin D with a fat-containing morning meal and calcium separately at bedtime. Check combined D/K and multivitamin products before adding more.

Food sources

Fatty fish; egg yolks; fortified milk or plant drinks; some UV-exposed mushrooms. Sun exposure is not a food source.

Supplement forms

D2 (ergocalciferol) and D3 (cholecalciferol). The usual blood-status marker is 25-hydroxyvitamin D.

A question to bring to your visit

What do my measured vitamin D and related clinical findings show, and am I duplicating fat-soluble vitamins?

What to track and reassess

Ask whether a 25-hydroxyvitamin D or calcium test is appropriate for you. A VDR variant alone is not a reason to begin high-dose vitamin D.

From starting support to follow-up

If you and your clinician start a CMA replenishment plan, you may add one new product at a time, often waiting 3–7 days to see how you feel. A check-in is usually planned near ten weeks during an approximately 100-day period. Follow your written plan for amounts and timing. At follow-up, you may continue, change, or stop each item. This timetable does not automatically end longer-term support.

Names you may see

Vitamin D