What’s all the hype about vitamin D?

What’s all the hype about vitamin D?

It seems as though all anyone can talk about these days is vitamin D. Every time we turn around there is a new study showing that vitamin D prevents a different disease. The debates swirl as to what dosages to use every time a new study comes out showing higher dosages equal less disease. The scientists doing the studies have been found to be taking 10 times the recommended dose, simply because they have been so struck by their findings! Where do you stand in all of this? Should you be supplementing with vitamin D and if so, how much? Why aren’t we getting it naturally from our foods and the sun?

Living in the northern latitudes, increased pollution, year-round sunscreen use are some of the reasons we simply aren’t getting enough sun to provide us with the vitamin D we need. Ordinary glass blocks almost all UV light. Any sunscreen with an SPF of 8 or greater blocks vitamin D synthesis. Eating more fish can provide us with vitamin D but you would have to eat fish 3 times a day to make up for lack of sunlight.  Perhaps these are the reasons that the studies show that supplementing the body with vitamin D is helping to reduce cancer, osteoporosis, diabetes, heart and kidney disease and multiple sclerosis.

How much should we supplement? Health Canada is still not willing to increase the recommended daily allowance of 600 IU’s even in the face of an abundance of research showing that levels may need to be as high at 4,000 IU’s. The Canadian Cancer Society now recommends 1,000 IU’s of vitamin D after studies have shown that 2,000 IU’s is not only safe but could reduce colorectal and breast cancer1. The most recent study done on pregnant woman and vitamin D has been very controversial because it is suggesting we increase the recommended daily dose to 4,000 IU’s. In the study they split up 600 pregnant women into three groups. One group received 400 IU’s of vitamin D, the second received 2,000 IU’s and the third 4,000 IU’s of vitamin D. There was a 50% reduction in infections and pre-term births in the 4,000 iu group with no adverse effects2.

We could go on and on about the studies but let’s get back to you. Should you supplement and how much? Unfortunately there is still no definitive answer as to the safe dose of vitamin D. It is reassuring that while Health Canada is not prepared to increase its basic recommended dose, it has stated that 4,000 IUs per day is safe. The Institute of Medicine (IOM) has concurred and also published daily dose of 4,000 IUs is safe. Yet, this does not mean this is the best dose for you. It is important to remember that vitamin D competes with other fat soluble vitamins such as vitamin A and K. It is not surprising that they are finding that these other vitamins can become deficient and cause health problems. Some caution and appropriate prescribing is very important. The best way to determine what dose of vitamin D you should be taking is to have your vitamin D levels measured. Your naturopathic doctor can help you to determine if your serum vitamin D levels are adequate and work with you to establish a dose that is appropriate for you. There are some large studies underway that will shed more light on the subject. In the meantime, get some sun, eat your fish and visit your naturopathic doctor.

1. Vitamin D for Cancer Prevention: Global Perspective. Ann Epidemiol. 2009 Jul 1;19(7):468-483, CF Garland, ED Gorham, AR Mohr, FC Garland

2. Evaluation of Vitamin D Requirements During Pregnancy. National Institutes of Health. 2010. BW Hollis, CL Wagner, D Johnson, TC Hulsey

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