Vitamin D Production: Six Important Factors

In summer, a short exposure of the face and forearms to the sun for 5-15 minutes between 10 a.m. and 3 p.m. (without sunscreen) is enough to get our daily dose of vitamin D. But, as every Canadian knows, it’s not always summer...

Factors affecting the production of vitamin D

Here are some important things to consider when trying to maintain your vitamin D levels:

• At certain latitudes during the fall and winter, UVB rays from the sun are insufficient for the skin to produce precious vitamin D. This is true for all people living north (or south in the southern hemisphere) of the 40^th parallel (Montréal is at the 45^th, Toronto is at the 43^rd, and Vancouver is at the 49^th).

• Long hours spent indoors, whether at the office or at home, reduce the time we are exposed to the sun. Subsequently, this affects our vitamin D levels.

• The use of sunscreen to prevent skin cancer and control photoaging is highly recommended. However, a sunscreen with a sun protection factor (SPF) of 15 blocks the production of vitamin D by 98%.

• People with dark skin produce vitamin D much slower than those with white skin.

• Statistics show the consumption of one or more servings of milk a day decreases with age, even though milk is our main dietary source of vitamin D.

• The capacity to produce vitamin D through the skin decreases after the age of 50; therefore, people over this age have higher vitamin D needs.