Vitamin D2 (Ergocalciferol)

Effects and Benefits

Core Identification

Common Names:
- Vitamin D2
- Ergocalciferol
- Plant vitamin D
- Vegan vitamin D
- Calciferol (historical)

Latin Name: N/A (Chemical compound: C₂₈H₄₄O)

Category: Vitamin

Uses

Traditional Uses

• Cod liver oil (containing vitamin D) has been used since the 1800s to prevent rickets
• Sun exposure was historically encouraged for bone health before vitamin D was understood
• UV-irradiated foods have been used therapeutically since the early 20th century

Modern Uses

• Bone Health Support - Regulates calcium and phosphorus absorption for bone mineralization | Research quality: Strong
• Key findings: Vitamin D is essential for calcium absorption; deficiency leads to rickets in children and osteomalacia in adults

• Source citations: Merck Manual, Encyclopedia of Vitamins

• Osteoporosis Prevention - Combined with calcium to prevent bone loss | Research quality: Strong

• Key findings: Calcium and vitamin D together prevent corticosteroid-induced bone loss and support bone mineral density

• Source citations: Gaby A-Z Guide, clinical trials

• Immune Support - Vitamin D receptors found on immune cells suggest regulatory role | Research quality: Moderate

• Key findings: Vitamin D modulates immune response; deficiency linked to increased infection susceptibility

• Source citations: Encyclopedia of Vitamins

• Vegan/Vegetarian Supplementation - Only non-animal dietary source of vitamin D | Research quality: Strong

• Key findings: Mushrooms exposed to UV light convert ergosterol to vitamin D2; high enough levels can support vegans through winter months

• Source citations: Hobbs - Medicinal Mushrooms, Western Materia Medica

• Mood and Seasonal Wellness - May support mood during low-sunlight periods | Research quality: Preliminary

• Key findings: Vitamin D deficiency associated with depression in some studies; supplementation results mixed
• Source citations: Doctors Book of Natural Health Remedies

Active Compounds

Primary Active Ingredients:
- Ergocalciferol - The vitamin D2 molecule itself; converted in liver to 25-hydroxyvitamin D, then in kidneys to active 1,25-dihydroxyvitamin D (calcitriol)
- Ergosterol - Precursor compound in mushrooms; converts to vitamin D2 upon UV exposure

Key Biochemical Actions:
- Regulates calcium absorption in intestines
- Promotes calcium and phosphorus deposition in bones
- Modulates over 1,000 vitamin D-responsive genes
- Supports parathyroid hormone regulation

Dosage Information

Standard Dosage:
- Form: Capsule, tablet, liquid, or fortified foods
- Amount: 600-800 IU (15-20 mcg) per day
- Frequency: Once daily with a meal containing fat

Therapeutic Dosage:
- Form: Capsule or liquid
- Amount: 1,000-2,000 IU per day for general insufficiency
- Purpose: Correcting deficiency, supporting bone health
- Duration: Ongoing with periodic blood testing; higher doses (up to 4,000 IU) for deficiency states
- Note: Doses above 4,000 IU should be monitored by healthcare provider

Maximum Safe Dosage:
- Daily maximum: 4,000 IU (100 mcg) without medical supervision
- Warning threshold: Doses exceeding 10,000 IU daily for extended periods may cause toxicity

Bioavailability Notes:
- Fat-soluble - must be taken with dietary fat for optimal absorption
- D3 may raise blood levels slightly more effectively than D2
- D2 has a shorter half-life in the body than D3
- Both forms are converted to the same active metabolite (calcitriol)

How to Take It

Timing:
- Take with largest meal of the day (containing fat)
- Can be taken morning or evening
- Consistent daily timing recommended

Form Considerations:
- Mushroom-derived D2 is just as bioavailable as supplement form
- UV-exposed mushrooms: 5-60 minutes of sun exposure dramatically increases D2 content
- Slicing mushrooms before sun exposure can increase D2 levels up to 10 times

Synergies - What It Works Well With

Complementary Supplements:
1. Calcium - Vitamin D enhances calcium absorption; both essential for bone health | Combined use prevents osteoporosis more effectively than either alone
2. Vitamin K2 - Directs calcium to bones rather than arteries | Synergistic support for bone mineralization and cardiovascular health
3. Magnesium - Required for vitamin D metabolism and activation | Deficiency impairs vitamin D utilization
4. Boron - May help prevent vitamin D and calcium loss in postmenopausal women

Avoidance - What NOT to Combine With

Supplement Interactions:
1. High-dose calcium without vitamin K - May increase risk of arterial calcification | Take vitamin K2 when supplementing both

Drug Interactions:
1. Corticosteroids (prednisone, dexamethasone) - Reduce calcium absorption and interfere with vitamin D activation | Severity: Moderate
- May require increased vitamin D and calcium supplementation
- Monitoring recommended for long-term corticosteroid use
2. Anticonvulsants (phenytoin, phenobarbital, carbamazepine) - May increase vitamin D metabolism, leading to deficiency | Severity: Moderate
- Patients on long-term anticonvulsant therapy often need vitamin D supplementation
3. Orlistat (Xenical, Alli) - Reduces absorption of fat-soluble vitamins including D | Severity: Moderate
- Take vitamin D at least 2 hours before or after orlistat
4. Cholestyramine and other bile acid sequestrants - Reduce fat-soluble vitamin absorption | Severity: Moderate
- Separate doses by 4-6 hours
5. Thiazide diuretics - May increase calcium levels; combined with vitamin D could cause hypercalcemia | Severity: Mild-Moderate
- Monitor calcium levels

Food Interactions:
- Mineral oil - Can reduce vitamin D absorption
- Very low-fat diets - Reduce absorption of this fat-soluble vitamin

Safety Information

Contraindications:
- Hypercalcemia (high blood calcium)
- Hypervitaminosis D
- Kidney disease with impaired calcium regulation
- Sarcoidosis and other granulomatous diseases (may cause hypercalcemia)
- Primary hyperparathyroidism

Side Effects:
- Common: Generally well-tolerated at recommended doses
- High doses: Nausea, vomiting, constipation, weakness, weight loss
- Toxicity signs: Hypercalcemia symptoms - excessive thirst, frequent urination, confusion, kidney stones

Long-Term Use:
- Safe at doses up to 4,000 IU daily
- Periodic 25-OH vitamin D blood testing recommended for higher doses
- Target blood level: 30-50 ng/mL for most individuals
- Over 100 ng/mL considered excessive; over 150 ng/mL considered toxic

Special Precautions:
- Pregnancy: Safe at recommended doses (600-800 IU); higher doses only under medical supervision
- Kidney disease: Use with caution; may require active vitamin D forms instead
- Dark-skinned individuals and elderly may need higher doses due to reduced synthesis
- Northern latitude residents: May benefit from supplementation during winter months

Primary Uses At-a-Glance

Primary: Bone health, calcium absorption, osteoporosis prevention, vegan vitamin D supplementation

Secondary: Immune support, seasonal wellness support, correcting deficiency in malabsorption conditions

Sources

Local Library:
- Hobbs, Christopher - Medicinal Mushrooms: The Essential Guide
- Western Materia Medica II (WRCHM)
- Weil, Andrew - Eating Well for Optimum Health
- Gaby, Alan R. - A-Z Guide to Drug-Herb-Vitamin Interactions 2nd Ed
- Moyad, Mark - The Supplement Handbook
- Ferriss, Timothy - The 4-Hour Body
- Moline, Peg - The Doctors Book of Natural Health Remedies
- Lust, John - The Natural Remedy Bible
- Cordain, Loren - The Paleo Answer
- White, Linda B. - 500 Time-Tested Home Remedies

General Knowledge:
- Institute of Medicine vitamin D recommendations
- NIH Office of Dietary Supplements
- Merck Manual clinical guidelines