A recent study published in the American Journal of Preventive Cardiology found that higher vitamin D doses do not ... 2,000, or 4,000 international units (IU) per day of vitamin D3 supplementation.
Around 600 to 800 IU a day should be plenty, unless your doctor instructs you otherwise. Extremely high levels of vitamin D can lead to irregular heartbeat, kidney failure and death. This is typically ...