Stay Healthy All Winter - Get Your Vitamin D

Update October 17, 2016

The calculator that I referred to in the original post is no longer active, luckily these apps are available and even easier to use than the original!

Opti-D Time Calculator

D VitaMeter

We have known for a very long time (at least 1926) that adequate levels of vitamin D reduce the incidence of respiratory infection, colds, and flu.  It is not so surprising then that as we head into the darkest time of the year –the winter solstice December 21st- the incidence of colds & flus are increasing. We do store vitamin D in our bodies from the summer, the problem is that by this time of the year, without adequate exposure to sunlight, we have used up our stores.

Your skin naturally produces, and then absorbs vitamin D (which is actually a hormone) with sun exposure. In the winter months it is likely that you are not getting enough sunshine to replenish your stores of vitamin D.  This niffty calculator will tell you how much sun exposure you would need to get at various times of the year. Only a few minutes every-other-day for the super pale (nearly transparent) like myself and up to 24 minutes if you have darker skin. 

As your stores of vitamin D drop, your ability to fight infection decreases leaving you with 3 options: 

1. Get sick.
2. Withstand the freezing temperatures and stand in a t-shirt outside at noon for up to 24 minutes every-other-day. 
3. Increase the vitamin D in your diet  - dietary supplementation.

Sources of Vitamin D...

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Obviously the best source of vitamin D is the sun. The second best source is whole natural foods rich in vitamin D. The next best source is supplementation of natural D3 (Cholecalciferol). Please avoid D2 (Ergocalciferol), several studies (including this one) have concluded that D2 "...should not be regarded as a nutrient suitable for supplementation or fortification".

I know that I don’t get enough vitamin D from my diet - a minimum of 600iu a day is required, I generally recommend ~1000iu daily during the winter months. You can increase your intake of vitamin D to 2000iu for 3-4 days when you are feeling sick.  Some research recommends taking up to 5000iu a day. I strongly recommend that you get your vitamin D levels tested if you are regularly taking more than 1000iu daily – vitamin D is a fat soluble hormone that can build up in your system and be toxic at high doses.

Foods that are naturally rich in vitamin D include: 

• sustainably harvested fatty fish like salmon, mackerel, herring, and sardines
• oysters (my favourite) 
• mushrooms, particularly shitake
• egg yolks
• liver (organic)

For a better idea how much vitamin D is in each of these foods take a look at either Food Sources of Vitamin D or Self Nutrition data. Please beware of vitamin D fortified foods as many of them are fortified with the inferior and potentially dangerous vitamin D2 (Ergocalciferol).

Fish liver oil, like cod, is a great source of vitamin D provided that it is sustainably harvested and tested for heavy metals and PCB contamination. The David Suzuki Foundation recommends cod from Alaskan waters. Avoid farmed fish oil at all costs – farmed fish have been proven to have high levels of pesticides, heavy metals and other toxic chemicals and those toxins accumulate in the liver and fat stores.

If you are buying pure vitamin D make sure it is D3 (Cholecalciferol). Please avoid D2 (Ergocalciferol). You can take a daily supplement of 1000iu or take one large weekly dose of 7000iu with food.