60-70% of Canadian’s are Vitamin D Deficient!
About 42% of the US population is vitamin D deficient with some populations having even higher levels
As we enter into the coldest and darkest months of the year the temperature and amount of sunshine aren’t the only things that drop. Vitamin D levels in the blood drop as well leaving many Canadians deficient and in most cases very deficient.
Why? Midday sunshine exposure on the skin is the best way to make Vitamin D. But as winter arrives our Northern Hemisphere is tilted away from the sun and the rays are less powerful making the proper amount of Vitamin D synthesis almost impossible.
Vitamin D Implications
Vitamin D deficiency has been linked with many diseases and conditions involving cardiovascular and bone health, immune system and cancer.
But how do we make Vitamin D?
Ultraviolet Radiation B or UVB hits the skin triggering cholesterol into a hormonal pathway leading to Vitamin D synthesis. Conversely, cholesterol levels may rise due to lack of sunlight conversion into Vitamin D during darker months. Also – melanin, the determinant of skin, hair and eye colour is our body’s natural sunscreen. This pigment absorbs UV radiation from the sun.
Because humans evolved over many thousands of years in more equatorial (sunny) regions like the horn of Africa – darker skin (more melanin) was preferred as it is more resilient to solar radiation (less chance of sunburn). This also means that those with darker skin require higher levels of sun exposure for Vitamin D synthesis then that of someone with lighter skin colour due to higher concentrations of melanin absorbing UVB. So as humans started migrating into more northern and southern climates with less sunshine our need for darker skin wasn’t as strong. Therefore generations of living in less sunshine resulted in lighter skin colour which meant that the skin was more sensitive to UVB radiation. (Think of what happens when fair skinned individuals go to the tropics – sunburns!). Although these adaptations have helped fair skinned individuals synthesize Vitamin D with less sunshine the amount of rays necessary in the winter months are not enough. Unfortunately sitting indoors all day staring at artificial sources of light does not help synthesize Vitamin D!
How Improve Vitamin D Levels
The only way to know for certain if you are deficient is to get a blood test to measure your serum 25 (OH) D levels. If you are deficient, as many of us are, start supplementing with cod liver oil – the best source of Vitamin D (1 Tbsp. = 1300IU). Shoot for at least 1000IU of Vitamin D/day. Vitamin D supplementation is extremely safe. Although milk is fortified with Vitamin D it isn’t the best source (1 cup = 120IU). Try and get out into the sun more and increase UVB ray exposure. Sunshine exposure guidelines – for those with light skin 15 minutes and those with dark skin up to an hour preferably in a more equatorial region. Use sunscreen if in the sun for longer periods. Even more reason to take a winter tropical getaway!
Jenn Reviews – 15 Health Benefits of Vitamin D
Office of Dietary Supplements – National Institute of health – Vitamin D
Statscan Vitamin D Study – Globe and Mail
This article is also featured on The GoodLife Blog.