Discuss with your doctor your need to check 25-hydroxy Vitamin D levels. Optimal levels are greater than 75 nmol/L. If you are low ,your doctor can determine the appropriate amount to supplement. The best sources of Vitamin D include five to 10 minutes of daily sun exposure (with no sunscreen), fortified milk or yogurt, and fatty fish such as salmon.
People who live in northern climates may be at increased risk of deficiency because of the lack of sunlight.