UK NHS Recommendation: 10 mcg (400 IU) daily for adults during October–March
Upper Limit (Safe Maximum):
Adults: 100 mcg (4,000 IU) per day
Children: Lower limits apply—check with a pediatrician
✅ Most over-the-counter supplements contain 400–1,000 IU—well within safe range.
❌ Risk comes from mega-dose pills (50,000 IU) or combining multiple supplements unknowingly.
🔍 Who’s at Higher Risk?
People taking high-dose prescriptions without monitoring
Those using multiple supplements (e.g., multivitamin + D3 + cod liver oil)
Individuals with kidney disease or sarcoidosis (conditions that increase Vitamin D sensitivity)
✅ How to Supplement Safely
Get tested first—ask your doctor for a 25-hydroxyvitamin D blood test before starting high doses.
Stick to recommended doses—10 mcg (400 IU) is enough for most people in winter.
