Learn more about vitamin D

Vitamin D helps in the formation of bones and teeth and muscle function. In addition to having an important role in supporting the absorption of calcium and phosphorus, vitamin D contributes to the process of cell division, maintaining calcium levels in the blood and to the functioning of the immune system.

Vitamin D is produced when our skin is exposed to sunlight, which provides 90% of our vitamin D. The other 10% of our vitamin D comes from certain foods, like fatty fish, milk and eggs, but it can be particularly challenging to get enough vitamin D in colder climates or during winter. Other factors, such as increased use of sun protection and increasingly closed-in lifestyles, have further reduced our access to vitamin D.

The truth is that 88% of the global population has insufficient levels of vitamin D. If you want to know your exact vitamin D levels, the most common way to measure it is through a blood test. These tests measure calcifediol, which is the most common form of vitamin D in the blood. Your doctor or healthcare professional can provide you with more information about testing, as well as advice about supplementation.

There are different units for representing vitamin D levels – ng/ml and nmol/l are common. For informational purposes, we've created an overview of what are commonly considered optimal vitamin D levels. Consult your physician to determine your personal needs.